Ophionthus Bernhauer, 1908

Rodríguez-Melgarejo, Maryzender & Chani-Posse, Mariana, 2021, On the rare Neotropical genus Ophionthus Bernhauer (Coleoptera: Staphylinidae: Staphylininae): redescription of the type species and description of a new species, European Journal of Taxonomy 735, pp. 15-33 : 18-20

Genus Ophionthus Bernhauer, 1908

Figs 1–6

Ophionthus Bernhauer, 1908: 328 .

Ophionthus – Bernhauer & Schubert 1914: 372 (catalogue). — Lucas 1920: 461 (catalogue). — Blackwelder 1944: 138 (checklist); 1952: 276. — Herman 2001: 2721 (catalogue). — Chani- Posse 2013: 10, 12, 14 (characters, phylogenetic placement); 2014a: 64, 68, 71, 76, 78 (characters, characters in key), 81, fig. 12h (habitus); 2014b: 252 (characters in data matrix). — Chani-Posse & Solodovnikov 2017: 95 (characters). — Chani-Posse et al. 2018b: 50 (checklist). — Asenjo et al. 2019 (catalogue). — Chani-Posse & Ramírez-Salamanca 2020a: 198, 209–210, 213–214 (taxon sampling, phylogenetic placement); 2020b: 238, 246 (discussion on characters and phylogenetic placement).

Type species

Ophionthus serpentinus Bernhauer, 1908 , fixed by monotypy.

Diagnosis

The genus Ophionthus can be differentiated from other genera of Neotropical Philonthina by the combination of the following characters: head and pronotum broadened anteriad, antennomere 1 at least twice as long as 2 and almost as long as antennomeres 2 and 3 combined, labial palpomere 2 cylindrical, protarsomeres 2–3 with discal setae on ventral surface and without marginal setae, prosternum with sternacostal ridge joining superior line of hypomeron, metatarsomere 1 almost twice as long as 5.

Redescription

DIMENSIONS. BL = 10.5–11.6. Body elongate, more or less parallel-sided, narrowing from seventh abdominal segment to apex ( Figs 1A , 2 A–B, 3A).

COLOURATION. Head, thorax, and abdomen shiny black to piceous, except apical half of tergum 7; apical third of sternum 7, and segments 8 and 9 yellow; mandibles, maxillary and labial palps, elytra, and legs dark brown; antennomeres 1–8 or 1–9 dark brown to black, 9–11 or 10–11 yellowish ( Figs 1A , 2 A–B, 3A).

HEAD. Subhexagonal and slightly transverse (male) to subquadrate (female) in shape, slightly broadened anteriad, narrower in female ( Figs 2A , 3A ) than male ( Fig. 1A ); nuchal ridge present; postmandibular ridge absent; postgenal ridge present; ventral basal ridge present, extending more or less parallel to ventral portion of postoccipital suture; infraorbital ridge present or absent; dorsal and ventral surface of head with scarce setation, microsculpture dense and undulate. Eyes large, moderately convex, occupying apical half of lateral margin of head, shorter than temples seen from above. Gular sutures joined before neck. Frontoclypeus with a short longitudinal groove. Antennae inserted closer to anterior margin of frontoclypeus than to eyes, moderately long, not reaching base of pronotum, increasing gradually in width toward apex; antennomere 1 without apical spine-like seta, distinctly longer than antennomere 2 and almost as long as antennomeres 2 and 3 combined; antennomere 3 slightly longer than antennomere 2; pubescence starting on antennomere 4 to 11. Clypeus entire and fused with frons. Labrum rectangular, distinctly emarginate, sclerotized except apical margin, with several setae and macrosetae at apical margin. Mandible prominent, 1.4× length of head, with setose prostheca well-developed, with a groove on dorso-lateral margin. Maxilla with lacinia elongate and densely setose along internal apical half margin, with galea prominent and densely setose at apex; maxillary palpus long, palpomeres 1 to 4 glabrous with scarce setae at apices; palpomere 1 small; palpomere 2 slightly curved, longest, shorter than 3 and 4 combined; palpomere 4 cylindrical, longer than segment 3. Mentum transverse, with anterior margin slightly emarginate, one seta at each latero-lateral corner. Labial palpus moderately long; palpomere 1 shorter than 2; palpomere 2 shorter than 3; palpomere 3 cylindrical, shorter than 1 and 2 combined.

PRONOTUM. Distinctly longer than wide, slightly broadened anteriad, front margin subtruncate, hind margin slightly arcuate, anterior and posterior angles rounded ( Figs 1A , 2A , 3A ); disk with two dorsal rows of punctures sub-parallel to each other; lateral puncture of pronotum bearing long macroseta separated from superior line of pronotal hypomeron by a distance more than three times as large as diameter of puncture; surface with fine and dense microsculpture. Prosternum without distinct midlongitudinal carina; basisternum longer than furcasternum, with transverse carina variable (either complete or rudimentary). Mesoventrite somewhat elongate, with sternopleural suture distinctly oblique; mesoventral intercoxal process rounded, forming an obtuse angle.

LEGS. Profemora slightly narrowed toward apex, with lateroventral medial spines; protibiae setose, excavated; protarsomeres 1–4 longer than wide, slightly flattened dorsoventrally and slightly widened apically, with long and curved discal setae (adhesive setae) underneath, without marginal setae; meso- and metatarsomeres 1–2 with strong and distinct marginal setae ( Fig. 3C ); metatarsomere 1 moderately longer than 5 ( Figs 1A , 2A , 3C ).

ELYTRON. Longer than pronotum, subbasal ridge curved and projected anteriad, punctuation moderately coarse and homogeneously distributed. Hing wing with veins CuA and MP4 fused, vein MP3 present.

ABDOMEN. Tergum I with paired prototergal glands manifested by invaginated capsules with small openings. Terga III–V with anterior basal transverse carina distinct, posterior basal transverse carina always distinct on tergum III, distinct to not distinct on terga IV–V; area between anterior and posterior carinae deeply and sparsely punctate; surface with fine and dense microsculpture of transverse and oblique waves.

MALE SEXUAL CHARACTERS. Tergum VIII with apex projected medially, forming an obtuse angle ( Fig. 1C ); sternum VIII slightly emarginate apically ( Fig. 1D ). Genital segment with laterotergal sclerites IX short, not dorsoventrally flattened, with apex rounded and not sexually dimorphic ( Fig. 2G ); sternum IX symmetrical, deeply emarginate apically, with several fine and short setae at each side of emargination, basal portion moderately longer than distal portion ( Fig. 1E ); tergum X with apex rounded ( Fig. 1F ). Aedeagus with parameres fused as a short, triangular sclerite, and completely fused to median lobe ( Fig. 1 G–H); median lobe elongate with apical part narrowed into a rather broad apex ( Fig. 1 G–H).

FEMALE SEXUAL CHARACTERS. Tergum VIII with apex projected medially forming an obtuse angle ( Fig. 2E ); sternum VIII with apex rounded ( Fig. 2F ); tergum X subtruncate ( Fig. 2G ); second gonocoxites each with a long macroseta proximally, with minute stylus bearing a long apical macroseta ( Fig. 2H ).

Immature stages

Unknown.

Geographical distribution

The genus Ophionthus , with two species known at present, has been recorded from the departments of Cajamarca, La Libertad, and Junín in Peru. Based on the information of the specimen labels (locality and habitat), Ophionthus is distributed mainly in the ecoregion of Peruvian Yungas ( Olson et al. 2001). However, according to Morrone´s regionalization (2014) those localities belong to the biogeographical province of Puna ( Figs 4–5 , Supp. file 1).

Bionomics

The species of Ophionthus are considered general predators as are the other genera of Philonthina . One specimen of O. serpentinus was collected in a clearing in montane forest and riverside shrubbery.

Figures

Fig. 1. Ophionthus serpentinus Bernhauer, 1908. Holotype, ♂ (FMNH). A. Habitus, dorsal view, after Chani-Posse (2014a). B. Original labels. C. Tergum VIII. D. Sternum VIII. E. Sternum IX. F. Tergum X. G. Aedeagus, lateral view. H. Aedeagus, dorsal view. Stippled areas in G represent membranes. Shadded areas in G and H represent internal sclerites Scale bars: A = 5 mm; C–H = 0.5 mm.

Fig. 2. Ophionthus serpentinus Bernhauer, 1908. ♀ (MUSM). A. Habitus, dorsal view.B. Habitus, lateral view. C. Right protarsomeres, ventral view.D. Details of discal setae from right third protarsomere, ventral view. E. Tergum VIII. F. Sternum VIII. G. Lateral tergal sclerites IX and tergum X. H. Gonocoxites of female genital segment. Scale bars: A–B = 5 mm; G–H = 0.5 mm..

Fig. 3. Ophionthus asenjoi sp. nov. Holotype, ♀ (IFML). A. Habitus, dorsal view. B. Original labels. C. Metatarsomeres 1 and 2 with strong and distinct marginal setae (arrows). Scale bar = 5 mm.

Fig. 4. Distribution map of Ophionthus serpentinus Bernhauer, 1908 and O. asenjoi sp. nov.

Fig. 5. Map of probable localities (correct spelling, see Supp. file 1) for the male holotype of Ophionthus serpentinus Bernhauer, 1908 collected in “Peruvia centralis” by Jelski in 1873.

Fig. 6 (continued on next page). Strict consensus of the 28 MP trees obtained showing the systematic placement of Ophionthus Bernhauer, 1908 within the Neotropical lineage of Philonthina Kirby, 1837 (tree length = 579; consistency index (CI) = 0.24; retention index (RI) = 0.71. Black circles: exclusive synapomorphies; open circles, non-exclusive synapomorphies. Numbers above circles are character numbers; numbers below circles represent character states. Support values are indicated in bold below the branches as follows: Bremer/Standard Bootstrap/Jack-knife (cut = 50 for resampling support values).