Toxidium cavicola, Ivan Löbl & Arnaud Faille, 2017

Ivan Löbl & Arnaud Faille, 2017, Toxidium Cavicola Sp. Nov., A New Cave Dwelling Malagasy Scaphidiinae (Coleoptera: Staphylinidae), Annales Zoologici 67 (2), pp. 345-348 : 346-348

Toxidium cavicola sp. nov.

( Figs 1, 2, 3–6 )

Type material. Holotype ♂: Madagascar Namoroka 29.X.2016 / Grotte Canyon S16°24.676’ E045°19.645’ z= 161m – A. Faille leg. ( MNHN).

Paratypes, 3♂♂, 1♀, same data as the holotype ( MNHN, MHNG).

Description. Length 2.05–2.22 mm, width 1.04–1.18 mm. Head and body reddish-brown, abdomen, femora and tibiae not or slightly lighter than prevailing body surfaces, antennae, mouth-parts and tarsi usually distinctly lighter than body. Frons barely convex, very finely punctate, without impressions. Antennae with length ratio of antennomeres as III 15: IV 17: V 22: VI 20: VII 24: VIII 15 IX 21: X 20: XI 23 (holotype). Pronotum with punctuation dense and very fine, visible at 30 times magnification, lateral margin striae visible in dorsal view, lateral contours appearing oblique in dorsal view, sinuate in lateral view. Minute point of scutellum exposed. Elytra each with basal striae joined to sutural and lateral striae; sutural striae subparallel, punctate; adsutural areas flat, slightly narrowed posterior level of scutellar tip, converging from elytral mid-length to apices; apical margins of elytra truncate. Elytral disc with punctuation consisting of two types of punctures. Basal sixth, surfaces along sutural striae and lateral margins, and apical third to halves of elytra very fine punctate, with punctures barely visible at 40 times magnification. Surfaces posterior basal sixth with stripes of coarse and dense punctures; lateral stripe widest. Coarse punctures well delimited, to part about as large as puncture intervals. Lateral striae of elytra with several coarse punctures. Hypomera not microsculptured, with barely visible punctation. Mesoventrite flat, distinctly, densely punctate and bearing short pubescence on median area. Mesanepisterna with punctulate microsculpture. Metaventrite not microsculptured, lacking impressions or striae, in middle flat, very finely punctate. Submesocoxal lines triangular, with several coarse punctures; submesocoxal areas 0.12 mm long, slightly longer than shortest intervals to metacoxae. Metanepisterna flat, narrowed anteriad, with straight, deep, groove-like suture. Metepimeron with sulcus at level of metanepisternal angle. Tibiae straight, metatibiae slightly shorter than metatarsi. Abdomen densely, very finely punctate, with punctulate microsculpture barely visible at 80 times magnification; sternite 1 with convex subcoxal striae.

Male characters. Protarsomeres 1 to 3 weakly widened. Aedeagus ( Figs 3–6 ) 0.90–0.91 mm long. Median lobe weakly sclerotized, with apical process weakly narrowed apically and rounded at apex in dorsal view, curved and almost acute apex in lateral view.

Parameres strongly sclerotized, almost evenly narrow from bases and to apical section, at apices distinctly narrowed in dorsal view; arcuate and evenly narrow to mid-length, from mid-length narrowed apically. Internal sac with ejaculatory ductus wide, bearing striate structures in apical section, X-shaped subapical sclerite and apical membranous vesicle (position in not extruded internal sac).

Etymology. The species epithet is a noun, meaning living in cave.

Diagnosis. Löbl & Leschen (2010) recognized five Malagasy species of Toaeidium, one of which is presently undescribed, due to the absence of male specimens. Toaeidium caľicola may be readily distinguished from two of those described species, T. rufonotatum Pic, 1915 and T. janaki Löbl & Leschen, 2015 , by its unicolorour elytra, and from all describ- ed Malagasy species by the large submesocoxal areas (being about as long as halves of the shortest interval between submesocoxal lines and metacoxae). The elytral punctation of the new species is also diagnostic. Unlike in T. caľicola , the four described Malagasy species have elytra uniformly punctate, while the undescribed “species 1” has a lateral patch of coarse punctures on each elytron. The aedeagal parameres are strongly curved in T. caľicola , similar with those in T. janaki , while the characters of the internal sac suggest relationship with T. rufonotatum.

paratype with extruded internal sac, scale = 0.2 mm; (6) ditto, internal sac, paratype, scale = 0.1 mm.

Discussion. Toaeidium caľicola sp. nov. was collected in a cave located in the northern part ot the Tsingy de Namoroka National Park, ca. 35 km Southeast of Soalala. These remarkable geological formations are isolated and they host a remarkable biodiversity ( Allorge & Haevermans 2015). The new species was discovered during the 2016 expedition organized by MNHN in Namoroka, which was focusing on the exploration of the northern part of the Tsingy. The Canyon cave is located in a remote area of the massif, on the side of a deep canyon crossing the Tsingy ( Figs 7, 8 ). It is a large cave with various underground passages, ending by a narrow joint. This is in the deepest part of this cave that Toaeidium caľicola sp. nov. was collected under stones and walking on the ground, together with various troglobites among which Opiliones, Spiders, Hemiptera Reduviidae and Cixiidae : Tflphlobriaeia namorokensis Synave, 1953, Blattodea Nocticolidae , as well as a new species of rove beetle ( Staphylinidae , Paederinae ) under study. By contrast, the Thai species Bironium troglophilum was found in large numbers on a cave wall, not on the ground as was T. caľicola , but exact diet and nature of their ecology requires further observation.

Figures

Figures 3 – 6. Toaeidium caľicola. (3) median lobe in dorsal view, holotype, scale = 0.1 mm; (4, 5) ditto, aedeagus in dorsal and lateral views,

Figures 7 – 8. (7) Tsingy de Namoroka, drone’s view showing the steep-sided canyons (photo: S. Gilson), (8) Namoroka, entrance of the Canyon’s cave.