Research Article |
Corresponding author: Heriberto López ( herilope@ipna.csic.es ) Academic editor: Oana Teodora Moldovan
© 2020 Rafael García, Carmelo Andújar, Pedro Oromí, Heriberto López.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
García R, Andújar C, Oromí P, López H (2020) Oromia orahan (Curculionidae, Molytinae), a new subterranean species for the Canarian underground biodiversity. Subterranean Biology 35: 1-14. https://doi.org/10.3897/subtbiol.35.52583
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A new blind weevil belonging to the genus Oromia Alonso-Zarazaga, 1987 is described, being found in the underground of the laurel forest of La Gomera (Canary Islands). Individuals were mainly collected in a colluvial mesocavernous shallow substratum, besides one specimen collected in the deep humic layer of soil. This new species has clear diagnostic differences from the other Oromia species. The number of taxa in this endemic Canarian genus increases to four species, easily identified using the key provided in this article. New data on other Canarian subterranean weevils are also provided.
Canary Islands, Coleoptera, subterranean, identification key, MSS, new species, weevil
The tribe Typoderini Voss, 1965 of the subfamily Molytinae Schoenherr, 1823 (Coleoptera: Curculionidae), is represented in the Canary Islands by three genera: Styphloderes Wollaston, 1873, Oromia Alonso-Zarazaga, 1987 and Baezia Alonso-Zarazaga & García, 1999 (
The genus Oromia includes three species to date: O. hephaestos Alonso-Zarazaga, 1987 and O. aguiari Alonso-Zarazaga, 1990 both from Tenerife, and O. thoracica Machado & López, 2015 from Gran Canaria. These weevils are found in different underground environments: O. hephaestos in a few lava tube caves on the northern slopes of Tenerife (
Oromia species are eyeless, with elongated and rather flattened bodies, slightly depigmented, all these being typical characters of weevils with a subterranean life style (
Several individuals of an unknown Oromia species were discovered in the laurel forest of the Canarian island of La Gomera, and the purpose of the present work is to provide its description.
The first individual of this new species of Oromia was discovered while sifting soil under a dead laurel stump in La Gomera laurel forest, within Garajonay National Park. Thereafter, we started a systematic sampling of the MSS in another location of this forest using subterranean traps especially designed for this environment (
After the study, the dirt deposited on the individuals was removed with a small paintbrush and warm water with dish-washing soap. For a comparative morphological analysis with respect to the other Oromia species, several specimens of O. hephaestos, O. aguiari and O. thoracica from the collections of the authors were used. Examination, dissection, measurements, and drawings were completed with the use of a Carl Zeiss Citoval 2 stereomicroscope with an ocular micrometer. Photographs were taken under magnification using a CanonPowershot A650 attached to a Zeiss Stemi 2000 stereomicroscope and processed with the program Zerene Stacker (V. 1.04, Zerene Systems, LLC., Richland, WA), combining them into a single image using pmax and dmap methods.
The material examined is deposited in the following collections:
HLH Personal collection of Heriberto López Hernández, Canary Islands, Spain;
IPNA-CSIC Invertebrates collection of the Instituto de Productos Naturales y Agrobiología (IPNA-CSIC), Tenerife, Canary Islands, Spain;
POM Personal collection of Pedro Oromí, Canary Islands, Spain;
RGB Personal collection of Rafael García Becerra, Canary Islands, Spain.
Taxonomic acts
Class Insecta Linnaeus, 1758
Order Coleoptera Linnaeus, 1758
Superfamily Curculionoidea Latreille, 1802
Family Curculionidae Latreille, 1802
Tribe Typoderini Voss, 1965
Genus Oromia Alonso-Zarazaga, 1987
Spain, Canary Islands, La Gomera: Reventón Oscuro, Garajonay National Park (28°7'27.08"N, 17°12'58.45"W, 1073 m a.s.l.).
Holotype : 1 ♂, La Gomera, Reventón Oscuro, Garajonay National Park (28°7'27.08"N, 17°12'58.45"W, 1073 m a.s.l.), MSS1/1, 3 January 2015, DNA771, P. Oromí leg. (IPNA-CSIC). Paratypes: same locality as the holotype, MSS2, 1♀, 5 February 2009, DNA688, P. Oromí leg. (IPNA-CSIC); MSS3, 1♀, 8 June 2010, DNA689, H. López & D. Hernández leg. (HLH); MSS1, 1♀, 7 January 2011, DNA690, P. Oromí leg. (POM); MSS2/4, 1♀, 16 November 2013, DNA572, P. Oromí leg. (POM); MSS1/3, 1♀, 3 January 2015, DNA770, P. Oromí leg. (POM). La Gomera, Hermigua, Monte de Los Acebiños, Garajonay National Park (28°08'20"N, 17°13'40"W, 1038 m a.s.l.), 1 ♂, 8 December 2008, R. García leg. (RGB).
Male. Total length (including rostrum) 3.7–4.9 mm (X̄ = 4.3 mm). Maximal width 1.1–1.5 mm (X̄ = 1.3 mm). Body reddish-brown to yellowish-brown (Fig.
Head globose, partially retracted into pronotum, carinated, with thick punctures, eyeless.
Rostrum (average length 1.1 mm) as long as pronotum and 4× as long as wide at apex. Rostrum dorsally parallel-sided, coarsely punctured and carinulated in basal half; apical half with a median keel and two pairs of lateral keels, all well-defined; each pair of lateral keels join at the end of metarostrum forming an elongated, narrow hexagon through mesorostrum, continuing from here as a single keel along prorostrum. Prorostrum smooth, punctured, with apical setae. In lateral view, metarostrum convex. Ventrally, rostrum with three carinae, median carina thin and weak, slightly defined or barely visible beyond the basal half, lateral carinae more robust.
Antennae with short bristles, inserted in apical third of rostral length. Scape smooth in the basal half, punctated and microreticulated surface in the apical half, 7.3× as long as its maximum width and 1.45× as long as funicule. First funicular antennomere obconical, 2.25× as long as wide; second obconical, 1.5× as long as wide, narrower than the first and half as long; funicular antennomeres 3 to 5 isodiametric, 5 to 7 slightly transverse. Club globose sub-rhombic, 2× as long as wide and as long as the last 5–6 funicular antennomeres.
Pronotum 1.1× as long as wide, anterior margin 0.66× as wide as posterior; with three strong keels from anterior to posterior margin, median one straight and two paramedian ones sinuous, and in addition two strong lateral keels; in dorsal view, these lateral keels form a sub-trapezoidal pronotum outline, rounded angles, widest at level of posterior third; margins between these angles variable, from straight to slightly sinuous. Surface mat, with well-defined punctation on keels and edges, microreticulate intervals and some microsetae on keels. Prosternum with three longitudinal keels that cut transverse prosternal furrow, leaving two well-defined foveae.
Scutellum not visible.
Pterothorax with elytra oblong, elongated, lacking humeral calli, almost parallel-sided with slight concavity towards middle; with microreticulate surface, punctation and pubescence similar to that on pronotum; 2.7× as long as pronotum and 1.78× as long as wide. Interstriae from barely defined to strongly costiform: odd interstriae strongly costiform, 7th forming marginal border without reaching apical callus; even interstriae barely defined, resulting in two rows of superficial punctures conforming striae between each interstria; 8th interstria not defined in the lateral declivity, 9th slightly careniform. Metasternum 3× as wide as long, with dense, deep, rugose punctation.
Abdomen with two first ventrites with shallower sparse punctation, disc of both depressed. Fifth ventrite with punctation similar to first two and 2.1× as wide as long.
Legs with dense coarse punctation, covered with setae. Procoxae separated by distance of 0.0125× of their diameter, 1.6× of distance from anterior margin of pronotum and 1.5× of distance from posterior margin of pronotum. Mesocoxae separated by distance of 0.5× their diameter. Pro-, meso- and metafemora respectively 4.7×, 4.4× and 6× as long as their maximum width. Protibiae 5.8× as long as wide at apex (without counting uncus), almost straight, with external edge irregularly denticulate, and with dense strip of setae in a slight inner apical concavity. Meso- and metatibiae 5.4× and 6.9×, respectively, as long as their maximum width. First metatarsomere 1.36× as long as wide; second transverse, 0.66× as long as wide; third strongly bilobed, transverse, 0.87× as long as wide; onychium 3.6× as long as wide, 2/3 of its length projected from the third metatarsomere.
Aedeagus. Penis symmetric in dorsal view, parallel-sided and with the apex briefly pointed (Fig.
Female. Similar to male, but with total length 5.2–5.5 mm (X̄ = 5.3 mm), maximal width 1.7–1.8 mm (X̄ = 1.78 mm). Rostrum longer than in males (1.5 mm). Scape 9.6× longer than wide; 6th and 7th funicular antennomeres 1.25× longer than wide. Elytra 2.42× as long as pronotum, 1.56× longer than wide. 5th ventrite 2.6× as wide as long. Pro-, meso- and metafemora respectively 3.6×, 4.3× and 5.4× as long as wide. Pro-, meso- and metatibiae respectively 6.2×, 6.8× and 7.6× as long as wide.
Spiculum ventrale
bilobed bearing about 16 macrosetae (Fig.
All collected individuals of Oromia orahan have the body total o partially covered by mud or dirt due to their subterranean life style, being often difficult to observe details of the tegument (scales, pores, keels, etc). The appearance of the individuals is very different when this dirt is removed (Fig.
Oromia orahan from La Gomera has outstanding morphological differences with respect to O. hephaestos from Tenerife and O. thoracica from Gran Canaria, regarding to size and shape of pronotum among other characters (see key to the species). However, O. orahan is close to O. aguiari from Tenerife, from which it differs by its longer and less curved rostrum, thicker scape, the shape of pronotum due the marginal keels (Fig.
Other differences related to the reproductive structures are: i) the aedeagus of O. orahan has parallel sides while in O. aguiari they are concave (Fig.
Specific name in apposition of Orahan, who was considered as the supreme god, creator of everything, by the aboriginal people of La Gomera.
The known distribution of Oromia orahan sp. nov. is restricted to Garajonay National Park, a protected area of approximately 40 km2 located on the central mountainous region of La Gomera. This National Park includes one of the best representations of laurel forest in the Canary Islands. This type of vegetation was thought to be a relict flora from South Europe and North Africa, extinct during the Tertiary period due to the effects of glaciations and the desertification in these areas (
In Monte de Los Acebiños we sifted leaf litter and soil under the stump of a dead laurel, and at other sites we washed soil following the first steps of the technique described by
In Reventón Oscuro we installed four subterranean traps following
All populations of Oromia orahan sp. nov. are located inside a natural protected area, well preserved, at least at the epigean level. So we can assume that this species is under no threat at the moment. However, in recent years we have detected an alarming correlation between the increase of the non-native polydesmid millipede Brachydesmus sp. in the subterranean habitats of the National Park and a considerable decrease in captures of native endogean invertebrates in subterranean traps. Specific studies on the effect of this polydesmid on the subterranean communities are necessary, to establish the real conservation status of this new species.
1 | Pronotum not constricted anteriorly and expanded over the head; ventral margin of antennal scrobe reaching middle of rostrum; metapleurosternal sulcus absent (Gran Canaria) | O. thoracica Machado & López |
– | Pronotum constricted anteriorly and not expanded over the head; ventral margin of antennal scrobe reaching base of rostrum; metapleurosternal sulcus present | 2 |
2 | Pronotum clearly longer than wide, median, paramedian and marginal-lateral keels absent; prosternum without keels; elytra large and elliptic, with all interstriae costiform, profile serrated (Tenerife) | O. hephaestos Alonso-Zarazaga |
Pronotum almost as long as wide, with strong median, paramedian and marginal-lateral keels; prosternum with three longitudinal keels; elytra large and oblong, odd interstriae strongly costiform and even interstriae barely marked, profile not serrated | 3 | |
3 | Lateral keels of pronotum bilobed, with a marked medial cutout, forming in dorsal view a bilobed outline; pronotum widest at the level of the apical lateral lobe or at the level of both lateral lobes; 8th interstria marked in the lateral declivity (Tenerife) | O. aguiari Alonso-Zarazaga |
– | Lateral keels of pronotum not bilobed, without marked medial cutout, forming in dorsal view a sub-trapezoidal outline; pronotum widest at level of posterior third; 8th interstria not marked in the lateral declivity (La Gomera) | O. orahan sp. nov. |
Besides the discovery of new species like Oromia orahan, the active searching of the fauna in the different subterranean habitats of the Canary Islands, especially in the subsurface layers, is providing new distributional data for some poorly known species which are worth to be recorded. The databases of biodiversity are very useful for a research, management, education and communication (
La Palma island. Barlovento, Punta Salvaje (28°49'25.34"N, 17°46'17.29"W, 124 m a.s.l.), 2 exx., 18 October 2019, sieving deep leaf litter under Euphorbia balsamifera, R. García leg. (RGB).
The Macaronesian endemic genus Barretonus Roudier, 1958 includes four species from Madeira and two from the Canary Islands. In the recent description of the last species (
La Gomera. El Cedro, Garajonay National Park (28°7'25.03"N, 17°13'26.88"W, 966 m a.s.l.; new grid (500×500 m) for El Cedro in the Biodiversity Data Bank of the Canary Islands (BDBC)), 2 exx, 17 March 2017, GEEI (Grupo de Ecología y Evolución en Islas) leg. (IPNA-CSIC); Teselinde (28°11'46.35"N, 17°17'15.55"W, 744 m a.s.l.), 2 exx, 18 March 2017, GEEI leg. (IPNA-CSIC).
The speciose genus Laparocerus includes one species from South Morocco and 221 taxa endemic either to Madeira or the Canary Islands (Machado, 2018), several of them having adapted to the different habitats of the underground as lava tubes, the MSS and the soil (
La Palma. Mazo, Lomo Oscuro (28°34'51.83"N, 17°46'53.59"W, 536 m a.s.l.), 1 ex, 11 January 2015; 1 ex. 17 January 2017, R. García leg. (RGB).
This other species of subterranean Laparocerus is endemic to the southern half of La Palma island, where it has always been collected in caves. We provide a new locality in which some specimens have been collected under big stones.
La Palma. El Paso, Cueva de la Torreta Tacande (28°38'21.87"N, 17°52'47.92"W, 677 m a.s.l.), 14 May 2019, eclosion from roots, R. García leg. (RGB).
This small, apparently edaphobiont species is only known from lava tubes of the southern half of La Palma. The cave where it has been recently found enlarges its distribution towards northwest, close to the limit of the geologically older northern half of the island.
We are grateful to David Hernández and Helena Morales for their help with sampling efforts. The English of this manuscript has been edited by Guido Jones, currently funded by the Cabildo de Tenerife, under the TFinnova Programme supported by MEDI and FDCAN funds. We acknowledge to Miguel Ángel Alonso-Zarazaga and Peter Hlaváč that helped to improve the paper with their constructive comments and suggestions, and to Garajonay National Park for the permits to study the invertebrate fauna along several years. This study was partly supported by the Spanish Ministry of Science (MINECO) (CGL2015-74178-JIN and CGL2017-85718-P).