Onychelmis longicollis ( Sharp, 1882 )

Linský, Marek, Čiamporová-Zaťovičová, Zuzana & Čiampor, Fedor, 2021, A revision of Onychelmis Hinton, 1941 (Coleoptera: Elmidae), with description of new species, DNA barcoding and notes on the geography of the genus, European Journal of Taxonomy 739 (1), pp. 1-35 : 7-9

Onychelmis longicollis ( Sharp, 1882)

Figs 2 A–B, 6D, 7C–D, 12B

Elmis longicollis Sharp, 1882: 138 .

Onychelmis longicollis – Hinton 1941: 67, figs 7–8. — Spangler & Santiago 1991: 497, figs 3–4. — González-Córdoba et al. 2016: 11, figs 5a–b, 7c–b.

Differential diagnosis

Onychelmis longicollis can be distinguished from all species of the genus by the combination of the following characters: 1) smaller size (CL: 1.27 mm); 2) tomentum on profemora reaching behind middle, on mesofemora to around middle ( Fig. 6D ); 3) humeri feebly developed; 4) prominent carina on sixth elytral interval present; 5) elytral punctures moderately impressed; 6) shape of aedeagus lanceolate ( Fig. 7 C–D).

Material examined

Holotype PANAMA • ♂; “ Elmis longicollis Type D.S. V.de Chiriqui 4-6000ft. Panama. Champion // ♂ // Type [red disc] // V. de Chiriqui 4000-6000 ft. Champion. // B.C.A. Col. I. 2. Elmis longicollis Sharp. ”; NHM.

Redescription

Male (holotype) BODY. Obovate ( Fig. 2 A–B); length 1.27 mm; width 0.60 mm; dorsum conveX, glabrous. Body with sparse, light yellowish setae. Hairy or scale-like tomentum distributed on following areas: genae, sides of prosternum, mesoventrite, metaventrite and abdomen, epipleura, and medial and lateral portions of bases of femora.

COLOUR. Head, pronotum and elytra black; venter dark brown with reddish tinge; trochanters, tibiae and tarsi brown; first two segments of antennae and tarsal claws pale brown.

HEAD. Partly retractable into prothoraX. Antennae with only 2 segments remaining; pedicel about twice as long as scape. Labrum with anterior margin almost straight; anterolateral angles broadly arcuate with numerous golden, recumbent hair-like setae; clypeus shorter and wider than labrum, about 3.5 times as wide as long; anterior margin slightly concave, anterolateral angles rounded; frontoclypeal suture almost straight. Eyes well developed, HW: 0.29 mm, ID: 0.14 mm, suboval in lateral view, protruding from head outline in dorsal view, circumocular surface raised. Frons convex between eyes.

THORAX. Pronotum widest behind middle, PW: 0.41 mm, PL: 0.43 mm; surface shiny, with narrow reticulation along basal margin and posterolateral angles, with dense tiny punctures; sublateral carinae absent, fine raised line indistinct; disc conveX, divided by a broad, deep transverse impression before middle; two prescutellar foveae separated by a raised line extending from base to apical discal half, connecting both halves and merging into them; anterior margin arcuate; posterior margin bisinuate; sides of pronotum convex before and after transverse constriction; lateral margins narrowly rimmed; posterolateral angles orthogonal;anterolateral angles slightly produced.Hypomeron finely microreticulate, widest in middle. Prosternum moderately long in front of procoXae, with anterior margin concave; sides raised around procoxae, forming carinae, not reaching anterior margin, prosternal process long, moderately broad and with posterior margin broadly rounded. Mesoventrite coarse, short and wide, with deep triangular groove for reception of prosternal process; posterior margin around mesocoxae raised. Metaventrite slightly wider than long, rugose, more or less shiny with setigerous punctures; disc convex with deep, medial, triangular depression in posterior half; discrimen in basal ¾; with one prebasal fovea on each side of metaventrite. Elytra (EL: 0.85 mm, EW: 0.60 mm) conveX, widest in anterior ¾; sides strongly declivous; surface shiny, with dense tiny punctures; elytral margin narrowly rimmed; humeri feebly developed; epipleuron tapering posteriorly. Prominent carina on siXth interval well developed, reaching ⅘ of elytron. Elytra with ten rows of small punctures, moderately impressed, separated by 1–2 times puncture diameter, diminishing toward lateral margins and elytral apeX. Scutellum subovate, flat. Legs moderately long; femora clavate; tibiae longest, apically with cleaning fringes. Tarsi 5-segmented, first four segments each with one fine pale, recumbent seta, fifth segment slightly shorter than remaining segments combined; claws with a large subbasal and smaller basal teeth.

ABDOMEN. With 5 ventrites. First ventrite with basal margin broadly rounded; fifth ventrite longest, apically setose, with posterior margin broadly arcuate. Aedeagus ( Fig. 7 C–D) elongate. Penis without fibula; corona in apical half; in ventral view conveX, from apical half tapering toward broad rounded apeX; in lateral view slender, evenly narrowed from base to slightly curved apeX. Parameres absent. Phallobase about 1.5 times as long as penis, subparallel, in ventral view straight, slightly curved in lateral view.

Female

Unknown.

Distribution

The species is reported from three countries ( Fig. 12B ), Colombia ( González-Córdoba et al. 2016), Nicaragua (Shepard pers. com.) and Panama ( Sharp 1882). However, the holotype, first illustrated herein, differs from the non-type O. longicollis from Colombia depicted in Spangler & Santiago (1991) and later followed by González-Córdoba et al. (2016), and it is possible that they in fact represent different species, and therefore the correct distribution of O. longicollis needs to be reviewed.

Remarks

As stated by Sharp (1882), the type specimen is in poor condition and some characters like tibial fringes, which Hinton (1941) incorrectly interpreted as plastron, are difficult to properly observe. Antennal segments 3–11, the left hind leg and the tarsus of the left mid leg are missing, the left elytron is broken, and the left foreleg is glued to the mounting point.

Figures

Fig. 2. Habitus of Onychelmis spp. A–B. O. longicollis (Sharp, 1882), holotype, ♂ (NHM). A. Dorsal view. B. Ventral view. C–D. O. whiteheadi Spangler & Santiago, 1991, holotype, ♂ (NMNH). C. Dorsal view. D. Ventral view. Scale bar = 0.5 mm.

Fig. 6. Tomentum on pro- and mesofemora of Onychelmis spp. A. O. leleupi Delève, 1968. B. O. lenkae sp. nov. C. O. lobata sp. nov. D. O. longicollis (Sharp, 1882). E. O. minor sp. nov. F. O. onorei sp. nov. G. O. splendida sp. nov. H. O. whiteheadi Spangler & Santiago, 1991. Drawings are schematic, bodies are divided to identical halves: left = male, right = female (note: females unknown for D and H).

Fig. 7. Aedeagi of Onychelmis spp. A. O. whiteheadi Spangler & Santiago, 1991, ventral view. B. O. whiteheadi, lateral view. C. O. longicollis (Sharp, 1882), ventral view. D. O. longicollis, lateral view. Scale bar = 0.1 mm.

Fig. 12. Distribution map of Onychelmis Hinton, 1941. A. New species described within this study. B. Published records of Onychelmis and potential distribution of the genus.