Four new representatives of the genus Allocyclops Kiefer, 1932 from semi-consolidated subsoil aquifers in Benin (Copepoda, Cyclopoida, Cyclopidae)

Several species of cyclopoid copepods were collected from improved and unimproved hang-dug-wells in the Republic of Bénin over the years 2009–2014. Fifty five wells located in seven different districts were sampled: 15 wells in the district of Pobè (Department Plateau) and 1 well in Kétou (Department Plateau), 4 wells in Porto-Novo District (Department Ouémé) and, 15 wells in Lokossa District (Department Mono),18 wells in Parakou District (Department Borgou), 1 well in Abomey-Calavi District (Department Atlantique) and 1 in Zogbodomè District (Department Zou). Among them, 4 new species of the genus Allocyclops Kiefer, 1932 were found and are described herein: Allocyclops spinifer sp. n., A. nudus sp. n., A. pilosus sp. n. and A. sakitii sp. n. They are compared with the three African species previously described. Allocyclops appears to be a sub-Saharan taxon specialized to thrive in the variable environment of subsoil aquifers in laterite deck beds. An identification key to the 7 different African Allocyclops species


Introduction
Within the context of a research program in the Republic of Bénin on the biodiversity of the subterranean realm in relation to water quality, pollution vulnerably and local use 48 wells were regularly sampled over a period of one year.Seven wells located in the close vicinity of the monitored wells were occasionally visited.Six of the seven areas are located in the drainage basin of the Ouémé: the area of Parakou in the north of the basin and the area of Kétou, Zogbodomè, Pobè, Abomey-Calavi and Porto-Novo in the south.The seventh study area, the district of Lokossa, belongs to the lower part of the Mono-Couffo drainage basin (see Fig 1).Physico-chemical characteristics of the Pobè and Parakou wells have been published (Lagnika et al. 2014a;2014b).Analyses of the other regions are currently under study.
The Republic of Bénin, a country 650 km long and 325 km at its widest, in South-West Africa is a sub-Saharan savannah region enduring a tropical climatologic regime: humid in the south, semi-arid in the north (Kottek et al. 2006;Peel et al. 2007).The principal rainy season spans from April to late July.A less intense rainy period is active in the southern part of the country from late September to November.The dry seasons are from December to April and from late July to early September.Wells, dug in the thick laterite deck beds, are of vital importance for the communities during the eight months of drought.They also provide possibilities to study various aspects of this subterranean habitat and the local human impact on this extreme variable environment (Bonsor et al. 2013).
African continental waters have been a very attractive study subject in zooplankton research.Large regions, however, of this vast continent remain unexplored (Dussart 1980).This is particularly true in regards of the fauna thriving in subsoil aquifers for which certain taxonomic groups are ignored because of inadequate sampling and, mainly, the lack of specialists (Boutin et al. 2011;Tuekam Kayo et al. 2012).
Among the copepods collected during this intensive study (i.e.mostly representatives of Afrocyclops Sars, 1927, Thermocyclops Kiefer, 1927, Mesocyclops Sars, 1914) no less than four different species which undoubtedly belong to the cyclopid genus Allocyclops were detected.They are described herein and compared with the 3 other African Allocyclops previously known.

Material and methods
In the following Tables 1-4 location and well characteristics are summarised (italics refer to the entries in the tables): "Total depth" of the well from ground level; "Ø" diameter of the well at ground level; "Water-level fluctuation": difference between highest level and lowest level of the water column; "Wall characteristics" differentiate the wells as either a handdug well with un-cemented "natural" walls, or "cemented" i.e. constructed by cemented concrete rings with the lower parts perforated; "Well closure" refers to the protection from superficial influences: wells can left unprotected and are "open" or closed by a pave "slab", corrugated "iron" or "wood"; "Principal use": "potable" means exclusively used as drinking  water, "domestic" when the water is used for all purposes, and "gardening" when used only for private household gardens.Sample dates are provided with the description of each species.Detailed information on the different drainage basins was extracted from the reports made available through the "Direction Générale de l 'Eau" (2008).
The occasionally sampled wells: at Abomey-Calavi located adjacent to the university grounds in the village of Zogbadjè (11.75  Biological samples of the water column were taken with a Cvetkov plankton net (funnel 200 µm mesh size, 150 µm below valve).Baited traps were used to collect bottom dwelling animals.Total depth, diameter (Ø), and mean water depth were measured with a decametre and the exact location with a Garmin® GPS60.Samples were fixed at the spot adding 100 ml of a 7% formaldehyde solution.Sorted out at the laboratory of the Zoology Department of the Abomey-Calavi University, each taxon has been stored separately and preserved in 70% ethanol.
Copepods were first observed in temporary slides (mounted in glycerol).Dissected animal parts are mounted on permanent slides in glycerol, the cover glasses sealed with a polyurethane varnish.Preserved specimens are stored in 75% buffered ethyl alcohol (with 5-10% glycerol).All material is stored in the Crustacea collection of the Royal Belgian Institute of Natural Sciences and inventoried with acc.nr RBINSc COP #.Observations and illustrations were made on a Leitz Diaplan phase contrast microscope equipped with a camera lucida.Abbreviations used in the descriptions: Aesth, aesthetasc; CIV-CV, copepodid stages 4 and 5; EXO, END, exopodite and endopodite, respectively; L/W ratio, length/width ratio; armature distribution of the leg ramal segments: Roman numerals refer to spines, Greek numerals to setae.3).
Etymology.derived from the Latin words spinula and ferre, respectively meaning small thorn and to carry, and referring to the spinular ornamentation on pediger 5, on leg 4 and on the caudal rami.
Additional material.
Caudal rami (Fig. 2D) cylindrical, 2.7-3.0 times longer than wide, with distinct triangular depression in anterior half of medial margin.Anterolateral seta short, pinnate, and inserted in posterior half, without spinules at insertion.Distolateral element slightly longer than ramus (ratio 1.2-1.3/1)and longer than medial terminal element (ratio 1.2-1.4/1).Distolateral element with widely spaced long and slender spinules along outer side of stem, with widely spaced setules along inner side; spinules present near its insertion.Medial element as long as caudal ramus, and pinnate.Dorsal seta, articulating on small basal part, shorter than ramus (ratio 0.8-0.9/1).Principal terminal caudal setae pinnate, with breaking plane present in both.Surface of rami with irregular and defuse pattern of minute spinules on dorsal and ventral side, triangular anteromedial depression clearly delimited dorsally.
Mandible, maxillule and maxilliped as in A. cavicola.General aspect of maxilla as in A. cavicola.Medial claw of maxillary basis (Fig. 4I) long and blunt, armed with 4 large teeth increasing in length medially.Accessory seta as long as claw, serrate on both sides in proximal half, on one side in distal half.Both elements on first endopodite segment with set of large spinules in middle.Distal half either smooth or with minute spinules along both sides of the stem.Terminal element on second endopodite segment articulating on segment, furnished with minute spinules along one side of the stem.Both lateral elements on second segment slender and naked.
Legs 1-4 protopodite (Fig. 6A, C, D, F, G).Praecoxa of legs 1-3 with short row of slender spinules along distal margin close to outer edge.Praecoxa of leg 4 smooth.Outer part of coxa with 2 (legs 1-3) or 3 (leg 4) short rows of spinules on frontal surface.Coxal caudal surface of legs 1-3 with set of spinules near proximal outer edge (see ex. for leg 2: Fig. 6D).Medial coxal seta of legs 1-4 pinnate and reaching beyond proximal endopodite segment.Intercoxal sclerites unadorned on both sides.Lateral distal edges crescent without ornamentation.Mediodistal region concave (legs1-3: Fig. 6B) or nearly straight (leg 4).Inner edge of leg 1 basis crescent, of legs 2-4 produced in sharp triangular process.Medial margin hairy in legs 1-3, naked in leg 4. Inner element on leg 1 basis present, serrate and reaching beyond proximal endopodite segment, but not beyond middle of distal segment.Outer element on basis of the legs setiform: longest on leg 1 basis, shortest one on basis of leg 2.
Legs 1-4 with 2-segmented rami (Fig. 6A, C, F, G).Exopodite and endopodite equally long.Rami with the following armament distribution: I,0 -II,I+1,4 0,1 -1,II,3 Outer distal edge of second endopodite segment of legs 1-3 distinctly protruded, of leg 4 small and as large as inner one.Frontal and caudal surface of leg segments of legs 1-2 and frontal surface of leg 3 unadorned.Caudal surface of distal endopodite segment of leg 3, and frontal and caudal surface of leg 4 segments with diffuse pattern of tiny spinules.
Caudal surface of proximal endopodite segment of leg 4 inflated.Distal endopodite segment of leg 4 twice as long as wide with inner terminal spine as long as segment.Outer terminal spine slightly longer than half inner one (ratio: 0.55-0.56).Inner terminal spine set with long slender spinules.Outer subdistal and inner setae, equally long, not reaching noticeably beyond longest (outer) terminal spine.
Leg 5 (Fig. 3E) confluent with pediger, represented by narrow crescent expansion.Ancestral basal segment represented by long pinnate element, and ancestral distal segment marked by narrow truncate elevation, bearing 2 elements: setiform outer one, spiniform medial one, the latter twice as long as the former.
Leg 6 vestiges located laterally with 3 elements: dorsal one short and setiform, middle and ventral one dwarfed, blunt triangular, with hyaline appearance.Valves unadorned.Copulatory pore located midventrally in anterior third of somite, leading to U-shaped duct (Fig. 3C).Anterior receptacle expanded with undulate frontal margin.Posterior receptacle produced caudally extending to middle of double-somite, bilobed.Lateral arms (= narrow canal-like rim extending from copulatory duct to genital aperture) straight.
Leg 5 (Fig. 3D) with expansion representing distal segment more accentuated than in female.Proportional lengths of armament as in the female.Spinule ornamentation on lateral and ventral surface of pediger less dense than in the female.
Leg 6 (Fig. 3B) represented as a large, unadorned, valve with outer distal edge distinctly produced bearing 2 elements: outer one setiform, half as long as medial spiniform element.
Variability.Animals from Well Pb 6 collected on 07/02/2011 are smaller with the body length of the females ranging from 875 to 1009 µm, that of the males between 890-895 µm.They display shorter caudal rami (L/W ratio 1/2.6-2.7) with slightly longer setae: distolateral one 1.3-1.4times longer than the ramus, and medial terminal element 1.1-1.3times longer than ramus.In all other respects they resemble A. spinifer sp.n. as described above.2).
Additional material.
Caudal rami (Fig. 7D) cylindrical with large mediodorsal triangular depression and 2.7 times as long as wide.Lateral anterior seta short, inserted at caudal end of median third.Distolateral element longer than ramus (ratio: 1/1.2-1.3),furnished with long slender and widely spaced spinules along outer side of stem, and widely spaced setules along medial side.Medial terminal element longer than distolateral one (ratio: 1/0.75) and ramus (ratio: 1/0.65).Breaking plane in both principal terminal setae present; each seta pinnate.Dorsal seta located in caudal third, near medial edge, articulating on short basal part and as long as medial terminal seta.Medial depression with two series of slim spinules (hairlike) arranged perpendicularly on principal axis of the rami.Posterolateral element with spinules at insertion, anterolateral one without.
Antennule 11-segmented with typical armature distribution.First segment with crescent row of slender spinules in proximal half (Fig. 4D).Aesthetasc on segment 8 as long as accompanying seta, linguiform, and reaching almost to distal margin of segment 9. Aesthetasc on segment 10 filiform, shorter than accompanying element and reaching beyond middle of terminal antennulary segment.Terminal aesthetasc as long as segments 9-11 combined, fused at base with seta.The latter longer than aesthetasc (Fig. 4C).
Antennal general aspect and armature as in A. cavicola.Frontal surface of coxobasis with defuse pattern of minute spinules in proximal half on and near outer margin (Fig. 5D).Caudal surface with 3 short rows of tiny spinules in proximal half: 1 near outer margin, 1 below a diffuse distal cluster of tiny spinules, and 1 near inner margin (Fig. 5E, F).
Mandible, maxillule and maxilliped as in A. cavicola.General aspect of maxilla as in A. cavicola.Medial claw of basis rather short and sharp, furnished with 4 large teeth increasing in length medially (Fig. 4K).Accessory element as long as claw, furnished with widely spaced spinules in proximal half, densely serrate in distal half.First endopodite segment with one smooth and one serrate element.Terminal element on second endopodite segment confluent with segment, with long widely spaced spinules in proximal half and densely serrate in distal half.
Legs 1-4 protopodite (Fig. 9A, C, F, G).Praecoxa of legs 1-3 completely devoid of ornaments, of leg 4 with a short row of spinules along distal frontal margin, near outer edge.Both sides of the coxa of legs 1-3 unadorned, except for short rows of min- ute spinules along the frontal distal margin.Leg 4 coxa with some spinules on the outer distal frontal edge.Caudal surface of leg 4 coxa with 2 short rows of narrow spinules near the proximal outer caudal edge, and one median row parallel with distal margin.Intercoxal sclerites smooth on both sides, with crescent unadorned laterodistal expansions in legs 1-3 (see ex. Fig. 9B).Leg 4 intercoxal sclerite (Fig. 9H) with concave distal margin, lacking laterodistal expansions.Medial coxal element present in all legs, pinnate and rather short, reaching slightly beyond the distal edge of the basis in legs 1-3, being shorter in leg 4. Medial element on leg 1 basis serrate and long, reaching to upper quarter of distal endopodite segment.Medial margin of leg 1 basis crescent and hairy.Outer seta of leg 1 basis longer than exopodite.Medial margin of legs 2-3 basis hairy, naked in leg 4. Distal inner edge of basis of legs 2-4 with short triangular expansion.Outer element on basis of leg 2 short, of legs 3-4 long.
Legs 1-4 with 2-segmented rami.Exopodite and endopodite of the legs equally long (Fig. 9A, C, F, G).Armament distribution and general aspect of segments as in preceding species.Segments devoid of ornamentation on frontal and caudal surface.Proximal endopodite segment of leg 4 flat, not expanded caudally.Leg 4 distal endopodite segment 2.2-2.3 times longer than wide with inner terminal spine slightly shorter than segmental length.Outer terminal spine half as long as inner one.Outer subdistal seta reaching to or just beyond tip of inner terminal spine, inner subdistal seta reaching far beyond tip of inner terminal spine.Proximal inner seta shorter than segment.
Leg 5 (Fig. 8A, B) confluent with pediger, represented as a single semi-circular expansion.Ancestral basal segment obsolete, represented by long pinnate seta.Ancestral distal segment represented by two equally long elements: outer one setiform, inner one spiniform.
Leg 6 (Fig. 6B) positioned laterally.Valve surface unadorned and bearing three elements on outer caudal edge: outer one setiform, median and medial one minute and truncate.Genital complex with copulatory pore leading to U-shaped duct.Lateral arms straight.Anterior receptacle expanded, with straight frontal margin.Posterior receptacle bi-lobed, expanded far caudally.
Leg 5 (Fig. 8C) as in the female.Leg 6 (Fig. 7 C) represented by large semi-ovate unadorned valve.Outer caudal edge expanded, bearing two elements: outer one setiform, medial one spiniform.The former shorter than the latter.
Variability: In most cases the medial triangular depression of the caudal rami is furnished with two parallel sets of fragile hairs as shown in Fig. 7D.In some specimens an additional row is present.Apart from the ornamentation of the caudal rami a single female shows an aberrant armament of the distal endopodite of right leg 2 with only 3 medial setae instead of 4. Body length and slightly different ratios of the caudal rami and armament are noticeable.Female body lengths range from 720 µm (Well A1 population) to 835 µm (Kéwi population); males from 620 (Well A1 population) to 800 µm (Kéwi population).Length/width ratio of the caudal rami varies between 2.4 to 3.0 with the laterodistal spine 1.2-1.4 and the terminal medial seta 1.6-1.9times longer than the rami.2).
Etymology.From the Latin adjective "nudus" meaning naked and refers to the absence of hairy or spinular ornamentation on the pedigers surface and caudal rami, contrasting the species from A. spinifer sp.n. and A. pilosa sp.n.
Additional material.
Antennule 11-segmented with typical armament, not reaching to posterolateral edge of cephalothorax.Segment 1 with set of slender spinules and set of short ones (Fig. 4 F).Aesthetasc on segment 8 linguiform, reaching beyond middle of segment 9. Aesthetasc on segment 10 filiform, shorter than accompanying seta and reaching halfway terminal segment.Aesthetasc on segment 11 tubular, as long as segments 9-11 combined, and shorter than accompanying seta (Fig. 4E).
Antenna with general appearance and armature as in A. chappuisi (see Fiers 2012).Frontal surface of coxobasis with a cluster of 7-9 small spinules near middle of outer margin and a row of slender spinules in proximal half near abexopodal margin (Fig. 5G).Caudal surface of coxobasis with 3 sets of narrow spinules in proximal half: 2 near outer margin, 1 near abexopodal margin (Fig. 5H).Mouthparts as in preceding species.Maxillary basis (Fig. 4J) prominent and blunt, with set of 4-5 large spinules in middle, increasing in length medially.Accessorial seta robust, with large spinules on both sides of the stem in proximal half, finely serrate along one side in distal half.Armature of proximal endopodite segment and terminal armature element on distal endopodite segment robust, with large spinules in proximal half and finely serrate in distal half on one side of the stem.Terminal seta on distal endpodite segment confluent with segment.Additional elements on distal segment sparsely serrate.
Leg 1-4 protopodite (Fig. 12A-D).Frontal margin of praecoxa with short row of slender spinules near outer corner.Frontal surface of legs 1-4 coxa unadorned except for some minute spinules along distal margin.Caudal surface of leg 1 unadorned, of legs 2 and 3 with some slender spinules near outer proximal corner.Caudal surface of leg 4 coxa with a transverse row of spinules parallel to distal margin and some slender spinules near outer proximal corner.Intercoxal sclerite of legs 1-4 as in preceding species.Medial coxal seta present, pinnate and reaching beyond basis, attending distal margin of proximal endopodite segment in leg 1, and middle of proximal endopodite segment in legs 2 and 3. Medial element somewhat shorter in leg 4. Medial margin of basis of leg 1 crescent, hairy, and with pinnate element reaching beyond proximal endopodite segment.Spinules present at its insertion.Medial margin of basis of legs 2-4 crescent, produced distally in short triangular expansion.Hairy in legs 2-3, naked in leg 4. Outer seta on leg 1 basis as long as exopodite, and as long as first exopodite segment in legs 2-4.
Leg 1-4 rami 2-segmented with general appearance and armament distribution as in preceding species.Frontal and caudal surface of ramal segments unadorned.Proximal segment of leg 4 endopodite inflated caudally (Fig. 12D).Distal endopodite segment of leg 4 2.10-2.15times longer than wide.Inner terminal spine as long as segment, and 1.8-2.1 times longer than outer spine.Medial setae on second endopodite segment equally long, not reaching beyond inner terminal spine.
Leg 5 (Fig. 11E) with ancestral segments confluent with pediger, represented as a semi-ovate expansion with a discreet truncation distally.Ancestral basal segment represented by a long setiform element.Ancestral distal segment represented by 2 elements: outer one setiform, half as long as medial spiniform element, both inserted on the distal discreet truncation.
Leg 6 (Fig. 11B) typically represented by 3 elements: outer one setiform, middle and medial ones dwarfed, hyaline and blunt.Valves unadorned.Genital complex with frontal and caudal parts of receptacles expanded.The former with undulate frontal margin, the latter with single medioventrally expansion.Copulatory pore leading to U-shaped duct (Fig. 11D).Lateral arms straight.
Male: Body narrower than female body (Fig. 10C).Prosome 1.5 times longer than urosome.Principal body flexure wide.Second urosomite (pediger 6) 2 times wider than long.Body length 795 µm (allotype, ranging from 744 to 817 in paratypes).Posterodorsal margins of prosomites and first urosomite narrow and straight.Posterior hyaline fringe margins of urosomite 2 narrow and serrate, of urosomites 3-5 wide and serrate.Anal somite with crescent, not expanded, anal operculum.Anal sinus smooth.Posterior margin of anal somite with uninterrupted row of spinules.
Antennule as described for A. cavicola in Fiers 2012.Mouthparts and legs 1-4 as in the female, except for leg 4 endopodite lacking expansion of caudal surface of the proximal segment.Leg 5 (Fig. 11C) with region representing ancestral distal segment more pronounced than in the female.Armature elements as in the female.
Variability.Except for slight variation (less than 15 µm) in the body length and the L/W ratio of the caudal rami and its armament, no structural differences were observed in the type series nor in the other populations.
Etymology.Named after Nestor G. Sakiti who initiated, in collaboration with Claude Boutin, subterranean biology research in Bénin, and supported the junior author initializing his investigations.
Additional material.
Caudal rami (Fig. 13C) cylindrical, between 2.5 and 2.6 times longer than wide, with triangular medial depression reaching halfway the margin.Integument of caudal rami smooth.Anterolateral seta short and pinnate, without spinules at insertion.Distolateral element equally or slightly longer than ramus (ratio: 1.0-1.1/1),furnished with widely spaced setules on both sides of the stem.Spinules at insertion of distolateral element present.Terminal medial element longer than ramus (ratio: 1.3-1.5/1)and pinnate.Principal terminal setae with breaking plane and pinnate.Dorsal seta, articulating on small basal part, and as long as medial element.
Antennule 11-segmented, not reaching to posterior edge of cephalothorax.Segment 1 with crescent row of spinules in proximal half (Fig. 4H).Aesthetasc on segment 8 linguiform, as long as accompanying seta, and reaching middle of segment 9. Aesthetasc on segment 10 filiform, as long as accompanying seta, and reaching nearly to distal end of terminal segment.Aesthetasc on segment 11 tubular, as long as segments 9-11 combined, and shorter than accompanying seta (Fig. 4G).
Antennary general morphology and armature as in A. chappuisi.Frontal surface of coxobasis with a cluster of minute spinules (6-7 spinules) in middle of outer margin and a short transverse set of slender ones in the proximal half bear the abexopodal margin (Fig. 5J).Caudal surface nearly completely naked only furnished with a few slender spinules in the proximal half near the abexopodal margin.(Fig. 5I).
Mandible, maxillule, maxilliped and general aspect of maxilla as in A. cavicola and the preceding species.Claw of maxillary basis blunt, armed with 8-9 large spinules, increasing in width and length medially.Claw shorter than accessory element (Fig. 4L).The latter furnished with groups of long spinules on both sides in proximal half and along one side in distal half, besides the finely serrate ornamentation of the distal part of the stem.Both elements on proximal endopodite segment and terminal element on distal segment furnished partially with long spinules along one side of the stem, finely serrate at the opposite side.Additional setae on distal endopodite segment slender, unequal in length.
Leg 1-4 protopodite without ornamentation on praecoxa (Fig. 15A, C, E, F).Frontal surface of coxa unadorned except for the usual minute spinules along distal margin.Caudal coxal surface smooth in leg 1, with some slender and short spinules near outer proximal corner in legs 2 and 3 (Fig. 15D).Caudal surface of leg 4 coxa with 2 small clusters of spinules near outer proximal distal corner and a median row of narrow spinules parallel with distal margin (Fig. 15F).Medial coxal seta present in  all legs, pinnate and reaching to middle of proximal endopodite segment in legs 1-3, but hardly beyond basis in leg 4. Intercoxal sclerites as in preceding species.Basis in leg 1 with long medial spine, reaching to middle of distal endopodite segment and with spinules at insertion.Medial margin of legs 1-3 crescent and hairy, naked in leg 4. Medial distal edge of basis in leg 1 rounded, slightly triangularly produced in legs 2-4.Outer seta on basis of legs 1 and 4 as long as exopodite, of legs 2 and 3 half as long.
Leg 1-4 rami 2-segmented with general appearance and armament distribution as in preceding species (Fig. 15A-C, E-F).Proximal segment of leg 4 endopodite slightly expanded caudally.Distal endopodite segment of leg 4 2.2-2.4 times longer than wide.Inner terminal spine shorter than segment (ratio: 0.9/1), outer spine half as long as inner one.Medial setae on distal endopodite segment of leg 4 reaching distinctly beyond longest terminal spine.Leg 5 (Fig. 14A, B) confluent with pediger, represented as a semi-circular expansion bearing 3 elements.Ancestral basal segment represented by long setiform element, ancestral distal segment by two equally long elements: outer one setiform, inner one spiniform.Surface of leg 5 expansion with some short and hairy-like spinules.Leg 6 (Fig. 14B) located laterally on genital double-somite, typically with 3 elements: outer one setiform, middle and medial one dwarfed, hyaline and blunt.Valve unadorned.Genital complex with small ovate anterior receptacle.Caudally expanded receptacle with single medioventral lobe.Copulatory pore leading to U-shaped duct.Lateral arms straight.
Male: General appearance of body as in the female with prosome 1.5 times longer than urosome.The latter with pediger 6 half as long as wide (Fig. 14G).Posterodorsal fringes of prosomite and first urosomite, and posterior fringes of urosomites as in the female.Body length: 676 µm (allotype and other male paratypes ranging between 650 and 695 µm; n=4).
Antennule as described for A. cavicola in Fiers (2012).Mouthparts and legs as in the female but proximal endopodite segment of leg 4 without expansion.
Leg 5 (Fig. 14G) with general appearance and integumentary ornamentation as in the female, but with outer setiform element on distal segment vestige longer than inner spiniform element.
Leg 6 vestige (Fig. 14G) large, with protruded outer distal edge, bearing 2 elements: outer one setiform, half as long as inner one.The latter spiniform.Surface of valve unadorned.
Variability: Apart from slight variation in body length and L/W-ratio of the caudal rami and the setae on the caudal rami, no structural variability was observed.

Differential diagnoses
The cyclopoid genus Allocyclops originally erected by Kiefer (1932) and recently redefined (Fiers 2012) corals four species with three African representatives: A. chappuisi Kiefer, 1932, A. cavicola Chappuis, 1951and A. beadlei (Lindberg, 1956) and one Central-American (A. botosaneanui Pleşa, 1981).The latter which deviates in many aspects from its three congeners has been tentatively retained in the genus but will certainly removed when its affinities to the South and North American cyclopines becomes clarified (Fiers 2012).The three known African representatives are described from sub-Saharan localities located in the tropical savannah region of continental Africa (Peel et al. 2007) Leleup 1956), and A. beadlei (Lindberg, 1956) from Uganda.
An unidentified cyclopine attributed to Allocyclops was reported from Morocco (Tuekam Kayo et al. 2012).The specimens have been re-examined by the senior author (35 ♀♀, 1 ♂: catalogued: RBINSc COP 9403, COP 9406, COP 10.132).They can, however, not be assigned to the genus Allocyclops but seems to be affiliated with Metacyclops Kiefer, 1927.Among the 4 species described here, A. nudus sp.n. resembles most closely A. chappuisi, type of the genus, and can be easily confounded with the latter.A. nudus sp.n. is however more robust and distinctly larger than A. chappuisi.Females of the former measure 895-962 µm and males 744-817 µm whereas females and males of A. chappuisi measure 720-740 µm and 650 µm, respectively (Kiefer 1932;1934).The laterodistal spine on the endopodite of leg 4 is less than half the length of the mediodistal element while in A. chappuisi it reaches slightly beyond the middle of the inner spine.The most obvious difference between both species are the proportional lengths of the middle seta and medial spine of leg 5 (in both sexes) and leg 6 of their respective males.In A. nudus sp.n. the medial spiniform element is distinctly longer than the middle seta in leg 5 and leg 6 whereas in A. chappuisi the female leg 5 medial spine is shorter than the middle one, and equally long in the male leg 5 and leg 6.
As for A. nudus sp.n., A. sakitii sp.n. resembles A. chappuisi in most aspects.A. sakitii sp.n. differs from the latter by the larger body dimensions (♀: 800-875 µm, ♂: 650-695 µm versus ♀: 720-740 µm, ♂: 650 µm), the longer caudal rami (L/W: ♀ 2.50-2.65 versus 2.33) and the longer distolateral element of the caudal rami (> than ramal length versus < than ramus).A. sakitii sp.n. might also be distinguishable from A. chappuisi by the presence of the hairy ornamentation on the lateral margin of pediger 5.However, presence or absence of ornamentation on pediger 5 in A. chappuisi could not be explicitly confirmed because of the condition of the material (see Fiers 2012).
A. pilosus sp.n. and A. spinifer sp.n. are readily distinguishable from all the other Allocyclops species by the presence of ornamentation on the caudal rami: pilose in A. pilosus sp.n., serrate in A. spinifer sp.n.The pilose structures on the rami of A. pilosus sp.n. remind to some extent the ornamentation on the caudal rami of A. cavicola but is quite different in the former because of the linear arrangement of the setules and their location restricted to the medial margin of the rami versus the dorsal, lateral and medial location, and the more abundant presence of the structures on the rami of A. cavicola.
The morphology of four new species described herein concerts completely with the amended diagnosis of Allocyclops as proposed by Fiers (2012).On the basis of their morphology (i.e.body shape, leg armament, buccal appendages) Fiers (2012)

Subsoil characteristics
Bénin is well endowed with a dense river system flowing from north to south in central and southern Bénin (Ouémé and Mono-Couffo basins).Drainages in northern Bénin (roughly above 10° N) form tributaries of the large West-African rivers and run northwest (Volta basin) and north-east (Niger basin).Rivers are particularly subject of a flashy response to rainfall.They retain most of the year a low water level (large rivers) or disappear completely at the surface (many second rank tributaries).Villages have always been dependent on presence of a sufficient supply of groundwater during the long periods of drought for which human made hang-dug-wells and natural springs in the laterite soils have been the solution.
Laterite soils are subsoils of equatorial forests, the savannahs of humid tropical regions and of the Sahelian steppes (Tardy et al. 1991;Tardy 1997).They are a product of intensive weathering of the basement rocks and show distinct horizons.Their extension varies from 5 to 10 m below the ground level with the general translocation of clays towards the base (Bonsor et al. 2013).The clayish base layers support a primary aquifer with a regional extension.Depending on the local topography, a narrow to wide zone stretches between the laterite and the basement rock on which the deeper aquifer (vadose) develops (Alassane et al. 2010;MacDonald et al. 2012).
The hydrodynamic properties of a laterite aquifer are characterized by extreme variations with rapid lateral throughflow in the upper horizon during the wet season, and a narrow range of natural groundwater levels for much of the year.The majority of wells studied herein show this rather shallow to low water level (Tables 1-4: water-level fluctuation).
Members of the genus Allocyclops display a curious combination of conservative and advanced features.The combination of the large body size, the fully developed mouthparts and the complete armature compliment on the legs is in contrast with the general image of a subterranean cyclopine.The 11-segmented antennules and the 2-segmented rami of the legs however, are in accordance with a subterranean life style.It is assumed (Fiers 2012) that Allocyclops branched off directly from a epigene stock.The harsh and extreme variable environmental epigene circumstances may have been the main forces which favored the invasion of the subsoil aquifer by the ancestor.Thus far, only A. chappuisi has been explicitly reported from a laterite spring (Kiefer 1932;Chappuis 1934).A. cavicola was discovered in a cave formed in a limestone outcrop of the laterite surroundings in Bas-Congo (Chappuis 1951;Leleup 1956 ).The poorly known A. beadlei was found in a marshy environment in Uganda (Lindberg 1956).The latter, clearly in a far state of decomposition, was possible washed out of the laterite deck beds.With the addition of the four herein described species, it appears that the members of the genus Allocyclops are particularly well adapted to live in the shallow and variable environment of laterite groundwater.The genus is, as far as conclusions can be drawn, a typical African sub-Saharan taxon (taking in consideration the temporary assignment of A. botosaneanui).

Figure 2 .
Figure 2. Allocyclops spinifer sp.n.A habitus in dorsal view B principal setae of left caudal ramus C habitus in dorsal view D anal somite and caudal rami, dorsal view.(Female RBINSc COP 10.304: A, B, D; male RBINSc COP 10.305: C).

Figure 3 .
Figure 3. Allocyclops spinifer sp.n.A urosome in ventral view B urosome in ventral view C copulatory pore and duct D leg 5 and lateral part of pediger, in ventral view E leg 5 and lateral side of pediger in ventral view.(Female RBINSc COP 10.304: A, C; RBINSc COP 10.306: E; male RBINSc COP 10.305: B, D).

Figure 7 .
Figure 7. Allocyclops pilosus sp.n.A habitus in dorsal view B principal caudal setae of left caudal ramus C habitus in dorsal view D anal somite and caudal rami in dorsal view (Female RBINSc COP 10.310: A, B, D; male RBINSc COP 10.312: C).

Figure 13 .
Figure 13.Allocyclops sakitii sp.n.A habitus in dorsal view B principal caudal setae of left caudal ramus C anal somite and caudal rami, in dorsal view D habitus in dorsal view (Female RBINSc 10.357: A, B; female RBINSc COP 10.354: C; male RBINSc COP 10.356: D).
surmised a close relationship between Allocyclops and certain African Metacyclops species.The new additions neither dismiss nor support this assumption.The lack of detailed information on the morphology of the African Metacyclops species stamps such coherent analyses.Key to theAfrican species of the genus Allocyclops, applicable for both genders 1 Leg 4 distal exopodite segment with 5 medial setae; Caudal rami with medial seta twice as long as ramus, at most .............................................................2 -Leg 4 distal exopodite segment with 4 medial setae; Caudal rami with medial seta 2.4-2.5 times longer than ramus ............................................A. beadlei 2 Caudal rami 3 times longer than wide at the most (between 2.3-3.0/1);Medial seta on caudal rami 1 to 1.5 times as long as ramus, at the most ...........3 to be restricted to the district of Pobè but was also detected in the occasionally visited well at Zogbodomè.It might be that the species has a preference to the southern and less elevated parts of central Bénin.Pobè and Zogbodomé are located in the Ouémé drainage basin.The occurrence of A. nudus sp.n. is restricted to the district of Parakou, in the northern and most elevated part of the Ouémé drainage basin.Allocyclops sakitii sp.n. occurs only near Lokossa located in the drainage basin flooded by the rivers Mono and Couffo.The presence of the latter species in the occasionally visited well at Abomey-Calavi (located at the western limits of the Ouémé basin) is probably a result of the mixing of the waters from the Ouémé and Mono-Couffo basins in the coastal zone.

Table 1 .
Sample localities and principal well characteristics in the district of Lokossa: presence of Allocyclops species (dark grey background), other copepods (light grey background) and absence of Cyclopoida (white background).

Table 2 .
Sample localities and principal well characteristics in the district of Parakou: presence of Allocyclops species (dark grey background), other copepods (light grey background) and absence of Cyclopoida (white background).

Table 4 .
Sample localities and principal well characteristics in the district of Porto-Novo: presence of Allocyclops species (dark grey background).

Table 3 .
Sample localities and principal well characteristics in the district of Pobè: presence of Allocyclops species (dark grey background), other copepods (light grey background) and absence of Cyclopoida (white background).