Oromia orahan Garcia & Oromi, 2020

Garcia, Rafael, Andujar, Carmelo, Oromi, Pedro & Lopez, Heriberto, 2020, Oromia orahan (Curculionidae, Molytinae), a new subterranean species for the Canarian underground biodiversity, Subterranean Biology 35, pp. 1-14 : 1

Oromia orahan Garcia & Oromi sp. nov. Figs 1 , 2 , 3

Type locality.

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.).

Type material.

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).

Description.

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. 1 ), vestiture glabrous, with tiny setae (6-8 μm) on elytral interstriae, and on edges and keels of pronotum; setae longer and more visible on rostral apex, antennae and legs. Apterous.

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. 2A ); dorsal plate strongly chitinised; clearly curved in lateral view, with acute apex and small callus; internal sac with densely arranged teeth in two longitudinal bands occupying the apical two thirds of tube. Spiculum gastrale robust and bowed with highly asymmetric arms (Fig. 2B ). Tegmen with macrosetae, short manubrium and short, subparallel, blunt-tipped parameroid lobes (Fig. 2C ).

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. 2D ); manubrium with short median arm forking into two longer arms forming obtuse angle. Ovipositor with free conical apical styles, bearing 7-8 macrosetae (Fig. 2E ).

Note.

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. 3 ), a common feature in all Typoderini ( Hlaváč, comm. pers.).

Differential diagnosis.

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. 4A ), deeper general punctation, and the 8th interstria not marked in the lateral declivity.

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. 4B ); ii) the manubrium of the spiculum ventrale of O. orahan has a short arm forking into two longer arms forming an obtuse angle, while in O. aguiari the manubrium is divided into two arms arising directly from the plate of the spiculum ventrale forming an acute angle (Fig. 4C ); iii) the tegmen of O. aguiari has subtriangular parameroid lobes whereas in O. orahan the lobes are subparallel, short and with blunt tips (Fig. 4D ).

Etymology.

Specific name in apposition of Orahan, who was considered as the supreme god, creator of everything, by the aboriginal people of La Gomera.

Habitat and distribution.

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 ( Cronk 1992; Médail and Quézel 1999; Nakamura et al. 2000), although this has been recently questioned ( Kondraskov et al. 2015). The laurel forest is a humid wood, in which approximately 15 broad-leaved, evergreen tree species from 10 different families form the canopy (e.g. genera Laurus , Ilex , Persea , Picconia ). This forest constitutes the ecosystem with the highest levels of arthropod diversity within Macaronesia ( Fernández-Palacios et al. 2017). Consequently, it is an interesting habitat for the exploration of the subterranean biodiversity. For this reason, we selected two localities in the Garajonay National Park to study the subterranean fauna using two different methods.

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 Arribas et al. (2016). Besides one individual of O. orahan sp. nov. collected with the first method, in this locality we found other interesting subterranean coleopteran species such as the weevils Laparocerus oromii Machado, 2008 and Torneuma aphroditae (Germann & Stüben, 2006), and the ground beetle Lymnastis gaudini gomerae Franz, 1965.

In Reventón Oscuro we installed four subterranean traps following López and Oromí (2010) in the MSS on a steep slope originated by colluviation at the base of rocky cliffs, but probably also increased by more recent stony debris slipping downslope during the construction of an old forest road. To install the traps, places with 100% canopy cover were selected, which render a permanent penumbra to the surface and humidity to the underground layer. This locality was especially rich in subterranean species, in which we collected the ground beetles Pseudoplatyderus amblyops Bolívar, 1940 and Lymnastis gaudini gomerae , the rove beetles Domene jonayi Hernández & Medina, 1990 and Micranops subterraneus Frisch & Oromí, 2006, the histerid beetle Aeletes gemmula (Wollaston, 1865), the scydmaenid Euconnus specusus Vit, 2004, the weevils Laparocerus oromii and Torneuma orbatum Wollaston, 1865, an undescribed woodlouse of the genus Venezillo , and the millipedes Glomeris canariensis Golovatch, 1987 and Thalassisobates emesesensis Enghoff, 2013.

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.

Figures

Figure 1. Habitus of Oromia orahan sp. nov. (female) in dorsal and lateral view.

Figure 2. Structures of the male and female genitalia of Oromia orahan sp. nov. A aedeagus in dorsal and lateral view B spiculum gastrale C tegmen D spiculum ventrale E ovipositor. Scale bars: 1 mm (A-C), 0.8 mm (D), 0.03 mm (E).

Figure 3. Appearance of mud / dirt covered (A) and clean (B) individuals of Oromia orahan sp. nov.

Figure 4. Structures of Oromia orahan sp. nov. (letters without asterisks) and O. aguiari (letters with asterisks) A pronotum B aedeagus C spiculum ventrale D tegmen.