Collembola from Hundidero-Gato Cave in Southern Spain, with the description of a new species of Entomobrya Rondani, 1861 (Collembola, Entomobryidae)

This paper deals with some Collembola from a cave at La Sierra de Grazalema (Málaga). In total, eight species of springtails were found. Two may represent new species but there is insufficient material available to prepare full descriptions (one species in the genus Ceratophysella, one in Hypogastrura), one species (Folsomides cf. ayllonensis) is identified to species, but differences from the nominal species suggest further studies may indicate the Grazalema populations represent a distinct form, and one other is described as new to science, Entomobrya virginiae Arbea, sp. nov. The new species is characterized by no sexual dimorphism in colour pattern, 5 central macrochaetae on Abd II and 4 macrochaetae on Abd III. For the identification and description of the new species, the set of characters proposed by Jordana and Baquero (2005) was used.


Introduction
The Hundidero-Gato system, within the Subbaetic Mountain range (Southern Spain), is a hydrogeological system composed by more than 10 km of galleries. This cave, located between the municipalities of Montejaque and Benaoján in the province of Málaga Due to the extension of the system, we have limited the study area to the most accessible part at the entrance. The coordinates of Hundidero are 36°43'39"N, 5°14'19"W, about 558 m above the sea level. The entrance of the cave has a width of 10 m and a height of approximately 60 m, and 400 m of depth accessible on foot.

Sampling
We used baited pitfall traps to collect invertebrates, which were placed in some areas of the cave that were susceptible to harbor fauna. For the pitfall traps we used clinical analysis cans (volume 150 ml), which were buried and filled with a modification of Turquin´s liquid (Domingo-Quero and Alonso-Zarazaga 2010). The traps were baited with Majorcan sausage (cured sausage from Balearic Islands made with pork, paprika, salt and other spices) as attractant (Belda-García et al. 2014). All collected specimens were preserved in 70% ethanol.
Two areas were sampled: the entrance to the cave, which covers about 400 m from the mouth to the first lake, and the area called gallery, a ledge located after about 20 m from the lake, about 20 m in the vertical of the wall, corresponding to the deepest area that was sampled. In total, sixteen pitfall traps were placed: four in semi-darkness (twilight) and four in total darkness in the entrance area; and five traps in soil with guano and three in soil without guano in gallery. The sampling was carried out in 2016 (both the entrance and gallery) and 2018 (only the entrance), and the traps were placed in the dates that the Natural Park of Sierra the Grazallema allowed us. The traps were in the cave for one week. The entry seasons established by the Park was governed by the activity of the bats, allowing us access from mid-March to mid-April and later from mid-August to mid-November, in order to not disturb the breeding and wintering periods of the bats.

Preparation and analysis
Some specimens were cleared in Nesbitt's fluid and were mounted in Hoyer's medium for compound microscope observation in phase constrast. Figures were drawn with a camera lucida.

Terminology
Chaetotaxy schemes in Entomobrya follow Szeptycki (1979), Jordana and Baquero (2005) and Jordana (2012). Symbols used in dorsal chaetotaxy schemes are: open circle in the figures stands for the presence of large mesochaetae or macrochaetae that could be absent in male and juvenile specimens but present in females, closed circle stands for macrochaetae that are always present, black chaetae-like drawings to sensilla, large black circles with a cross line to pseudopores, long chaetae to bothriotricha.
Material studied. Cueva del Gato, twilight zone, 27-III-2016, 1 ♀ The single individual collected apparently represents an undescribed species similar to C. norensis Cassagnau, 1965, characterized by A-type of chaetotaxy (p1 chaeta shorter than p2 chaeta on Abd IV), dens with 6 chaetae, the basal chaeta more than twice as long as the others, retinaculum with 4+4 teeth, tibiotarsi with one pointed tenent hair, claw with one internal tooth and two lateral teeth, filament of empodium 2/3 as long as the inner edge of claw, Ant IV with trilobed apical bulb and 7 thin sensilla, slender anal spines 1.5 times the long of the claws and 1.8 mm length. The species is dark blue and does not show characters typically present in cave-adapted species.
Additional material is needed to confirm the identity of the species.
Material studied. Cueva del Gato, twilight zone, 27-III-2016, 1 juv. The single individual collected appears to represent a new species similar to H. vernalis (Carl, 1901), characterized by tibiotarsi with one slightly knobbed tenent hair, empodium with broad basal lamella, dorso-lateral parts of Th II-III with m6 chaeta, Ant IV with trilobed apical bulb and 7 sensillae, dens with 6-7 chaetae, 2.7 times as long as mucro, PAO nearly the same size as an ommatidium, anal spines minute, on high papillae, coarse body granulation (8 granules between the p1 chaetae of Abd V) and 1 mm length. The species is grey-blue and does not show characters typically present in cave adapted species.
Additional material is needed to confirm the identity of the species.
Material studied. Cueva del Gato, twilight zone, 27-III-2016, 16 ex; dark zone, 14-IV-2016, 1 ex, 13-XI-2016, 2 ex, 4-X-2018, 25 ex; cave galleries, 14-IV-2016, 1 ex, 30-IX-2016, 1 ex. Edaphic and troglophilous, guanophilous species. This is a common European species in the caves of the Iberian Peninsula (Spain and Portugal) and the Balearic Islands (Jordana et al. 1997).  Sánchez (2015). In brown, the twilight pitfall traps, in blue, the darkness pitfall traps and in red, gallery traps (five on guano and three on ground without guano). The different species that appear in each area are represented with their own symbol in the legend.
Material studied. Cueva del Gato, twilight zone, 27-III-2016, 3 ex, 16-VIII-2018, 1 ex. This is a cosmopolitan species known to occur in dry habitats, surface leaf litter or lichens on rocks (Thibaud et al. 2004). May appear in the mesovoid shallow substratum or in caves accidentally.
The species lacks pigment, but has 5+5 eyes. The juvenile (0.5 mm) examined differ from F. ayllonensis, as original description (Simón and Luciáñez 1990) and notes made by Fjellberg (1993), in having an oval postantennal organ, 1.7-1.8 as long as omma (>2 in F. ayllonensis), and in having three posterior chaetae on dens (two in F. ayllonensis). The physical distance (≈690 km) and morphological differences between the Grazalema and Ayllón populations suggest they may represent distinct species, but additional material from Sierra de Grazalema will be needed to determine if the morphological differences noted here are fixed.
Etymology. The name is dedicated to Virginia García López, who captured the specimens.
Head. Eight eyes, GH smaller than EF. Antennae length 1.08 mm, 3.13 times the length of the head (n = 16, Table 1); Ant IV with apical vesicle simple ( Fig. 10) (slightly bilobed in some specimens); relative length of Ant I/II/III/IV = 1/2.38/2.42/2.43 (Table 1). Labrum with 4/5,5,4 chaetae; prelabral chaetae ciliated, and labral chaetae smooth. The labium has MR*ELL ciliated Mc; R* half as long as M; the remaining labial Mc are smooth. The maxillary palp has three sublobal chaetae. The papilla E has a lateral process reaching the end of the papilla (Fig. 9). In the dorsal head chaetotaxy (Fig. 4), the H1 area has three Mc: An2, An3e1 and An3, and the H2 area with two Mc: A5 and A6 (sometimes absent or as mc in male and juvenile specimens); Mc series M with M1-M4; the H3 area without Mc S'0; the H4 area with S1, S3 and S4 Mc, and the H5 area with Ps2 and Ps5 Mc. There are four chaetae on the ocular well: p, q, r and s. Thorax (Fig. 5). Th II has two Mc: m1 and m2i, on the T1 area; the T2 area has four Mc: m4, m4i, a5 and a5' (sometimes absent or as mc in male of juvenile specimens). Th III has complete basal chaetotaxy: a1-a7, p1-p6, m6-m7.

Discussion
The number of springtails collected is higher in dark zone (58% of all Collembola collected), but the twilight zone proved to be the most richness -of the eight species recorded in this study, we recorded seven in the twilight and only five in the dark zone (Figs 16, 17). The troglophilous species Ceratophysella sp., Hypogastrura sp. and Xenylla maritima were recorded from only the twilight zone at the cave entrance (Fig. 1).
Four of the eight species were represented by only one to four specimens (Fig. 18). The high number of individuals is attributable to two species, Entomobrya virginiae sp. nov., for which 356 specimens (59.6% of all springtail specimens collected during this study) were collected from all zones of the cave, and Lepidocyrtus flexicollis with 121 specimens. The next two most abundant species were Sphaeridia pumilis, with 66 specimens (11% of all Collembola collected), and Mesogastrura ojcoviensis, with 47 specimens (7.9% of all Collembola collected).