Onychelmis lobata, Linský & Čiamporová-Zaťovičová & Čiampor, 2021

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 : 14-16

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Onychelmis lobata

sp. nov.

Onychelmis lobata sp. nov.


Figs 3B View Fig , 4 View Fig , 6C View Fig , 8 View Fig C–D, 11B, 11F, 12A–B

Differential diagnosis

Onychelmis lobata sp. nov. can be distinguished from all species of the genus by the combination of the following characters: 1) moderate size (CL: 1.35–1.37 mm); 2) pro- and mesofemora with tomentum at base in males, and around middle in females ( Fig. 6C View Fig ); 3) humeri produced; 4) prominent carina on sixth interval present; 5) elytral punctures shallowly impressed; 6) apex of aedeagus broadly rounded, medially with arcuate projection ( Fig. 8 View Fig C–D).


The species is named after its larva (to be described in a separate study), which possesses distinct cuticular lobes.

Material examined

Holotype ECUADOR • ♂; “Ecuador, Napo prov., road to Coca, 00°43′39.6″ S, 77°45′56.1″ W, 1129 m a.s.l., 17. 8. 2013, small waterfall, Čiampor & Čiamporová-Zaťovičová lgt. ”; PUCE. GoogleMaps

Paratypes ECUADOR • 4 ♂♂, 5 ♀♀; same collection data as for holotype; PUCE / CCB GoogleMaps 1 ♂; “ Ecuador, Napo prov., road to Coca, Sumaco env., 00°43′29.0″ S, 77°46′01.4″ W, 1109 m a.s.l., 17. 8. 2013, confluence of two larger streams, with gravel, stones, boulders, Čiampor & Čiamporová-Zaťovičová lgt. ”; PUCE / CCB GoogleMaps 1 ♂ “Ecuador, Napo prov., road to Coca, Sumaco env., 00°42′25.7″ S, 77°43′10.0″ W, 1138 m a.s.l., 17. 8. 2013, stream ca. 2-3 m wide, fast flowing, with boulders, stones, gravel, submerged wood, Čiampor & Čiamporová-Zaťovičová lgt ”; PUCE / CCB GoogleMaps .

Other material

ECUADOR • 1 ♂, 5 ♀♀, 1 larva; same collection data as for holotype; CCB GoogleMaps .



BODY. Obovate, black ( Fig. 3B View Fig ); length 1.35–1.37 mm; width 0.62–0.68 mm; dorsum conveX, glabrous with sparse, light yellowish-brown setae. Hairy or scale-like tomentum distributed on following areas: genae, sides of prosternum, mesoventrite, metaventrite and abdomen, epipleura, and medial and lateral portions on bases of femora.

COLOUR. Head, pronotum and elytra black; venter, mouthparts, prosternum, coxae, tibiae, tarsi, metaventrite and abdomen brown to dark brown with reddish tinge; trochanters pale brown to reddish brown; basal segments of antennae and tarsal claws pale brown.

HEAD. Partly retractable into prothoraX, dorsally shiny. Antennae filiform, 11-segmented; pedicel about twice as long as scape; remaining segments about 4 times as long as scape and pedicel combined; segments 3–10 subrectangular, subequal in length; terminal segment longest, suboval, with pointed apex. Labrum with anterior margin very slightly emarginate medially; 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: 0.27–0.30 mm, ID: 0.12–0.15 mm, suboval in lateral view, protruding from head outline in dorsal view, circumocular surface raised. Frons between eyes convex.

THORAX. Pronotum widest behind middle, PW: 0.41–0.42 mm, PL: 0.47–0.48 mm; surface shiny, with narrow reticulation along basal margin and posterolateral angles, with dense tiny punctures; sublateral carinae never well-developed, fine raised sublateral lines indistinct; disc conveX, divided by a broad, deep transverse impression before middle; prescutellar foveae separated by a raised line extending from base to middle, connecting pre- and postimpression portions 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, 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, shiny with setigerous punctures; disc convex with deep, medial, triangular depression in posterior half; discrimen in basal ¾, very thin, indistinct; with prebasal fovea on each side of metaventrite. Elytra (EL: 0.88–0.91 mm, EW: 0.62–0.68 mm) conveX, widest in anterior ¾, sides strongly declivous; surface shiny, with dense tiny punctures; elytral margin narrowly rimmed; humeri protruding from outline; epipleuron tapering posteriorly. Prominent carina on siXth interval reaching ⅘ of elytron. Elytra with ten rows of small, shallowly impressed punctures, separated by 2–4 times puncture diameter, diminishing toward lateral margins and elytral apeX. Scutellum subovate, flat. Legs moderately long; femora clavate; tibiae longest. Protibiae with anterior cleaning fringe on apical ⅓; mesotibiae with two cleaning fringes – anterior on apical ⅕ and posterior on apical ⅓; metatibiae with posterior cleaning fringe on apical ⅓. 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 ( Fig. 4A View Fig ). Aedeagus ( Fig. 8 View Fig C–D) elongate. Penis without fibula; corona in apical half; in ventral view subparallel, apically widened, apeX rounded with medial protuberance; in lateral view curved, evenly narrowed from base to apeX. Parameres absent. Phallobase about as long as penis, parallel-sided, in ventral view straight, slightly curved in lateral view.


Externally similar to male, except metaventrite without distinct medial, triangular depression in posterior half and without two prebasal foveae, fifth ventrite more elongate ( Fig. 4B View Fig ) and eXtension of femoral tomentum greater.


Collected from small stream directly below waterfall surrounded by remnants of primary forest, with water flowing between larger stones ( Fig. 11B View Fig ).


Known from three localities in Napo Province ( Figs 11B, F View Fig , 12 View Fig A–B).


Central College, Bangalore