Hexanchorus cordillierae ( Guerin Meneville , 1843)

Linsky, Marek, Ciamporova-Zatovicova, Zuzana & Ciampor Jr, Fedor, 2019, Four new species of Hexanchorus Sharp from Ecuador (Coleoptera, Elmidae) with DNA barcoding and notes on the distribution of the genus, ZooKeys 838, pp. 85-109 : 88-91

Hexanchorus cordillierae ( Guerin Meneville, 1843) Figs 1, 2, 12, 13, 23, 24, 36

Material examined.

(PUCE, NMW, CCB): 21 ♂♂, 10 ♀♀: "Ecuador, Napo prov., river near Don Napo ranch, Río Anzu, 01°14 ’17.2” S, 77°52 ’56.0” W 542m a.s.l., 13.8.2013, at light, Čiampor & Čiamporová-Zaťovičová lgt."; 1 ♂ "Ecuador, Pastaza prov., 10 de Agosto env., 01°21 ‘37.1“ S, 77°51 ‘55.7“ W 900m a.s.l., 16.8.2013, stream ca 1m wide, above confluence with larger stream, fast flowing with boulders, Čiampor & Čiamporová-Zaťovičová lgt."; 5 ♂♂, 5 ♀♀ "Ecuador, Napo prov., road to Coca, Sumaco env., 00°43 ‘29.0“ S, 77°46 ‘01.4“ W 1109m a.s.l., 17.8.2013, confluence of two larger streams, with gravel, stones, boulders, Čiampor & Čiamporová-Zaťovičová lgt."; 5 ♂♂, 5 ♀♀ "Ecuador, Pastaza prov., Río Uklan, 01°17 ’13.8” S, 77°38 ’52.5” W 468m a.s.l., 18.8.2013, bigger river with lowland character, stream ca 15m wide, slow flowing with small riffles, with boulders, rock tables and sand, Čiampor & Čiamporová-Zaťovičová lgt.".

Diagnosis.

Hexanchorus cordillierae can be distinguished from all species of the genus by a combination of the following male characters: 1) smaller size (CL: 2.96 - 3.16 mm); 2) mesotibiae with medial pubescent area long, reaching short of apex and lateral pubescent area long, extending to 2/3 of tibia; 3) mesotibiae with short thorn-like carina on inner apex; 4) metatibiae with feeble thorn-like carina on inner apex; 5) elytra with rounded apices; 6) fifth ventrite deeply and broadly emarginate; 7) aedeagus with right margin slightly dilated in middle in ventral view.

Redescription.

Male. Body elongate, subparallel, dorsum moderately convex (Fig. 1). Length (CL) 2.96 - 3.16 mm; greatest width (EW) 1.12 - 1.15 mm; dorsal side dark brown with greenish iridescence; venter brown to almost black, tarsal claws reddish-brown. Dorsal surface densely covered with short recumbent setae and sparser, longer, dark, semi-erect setae; ventral surface densely covered with longer, golden, recumbent setae, especially on trochanters.

Head partly retractable into prothorax. Clypeus with anterior margin straight, about three times wider than long, shorter and narrower than labrum. Labrum feebly emarginate anteromedially, expanded laterally with sides broadly rounded, densely setose. Frontoclypeal suture visible, almost straight. Eyes suboval in lateral view, protruding from head outline, bordered by long black curved setae ( “eyelashes”) that arise near dorsal and ventral sides of eyes and extend toward middle of eye. Antenna moniliform, 11-segmented, pubescent; first two segments with dense long, dark brown setae, rest of antenna with only few such setae on sides; scape curved, about twice as long as pedicel, remaining segments about three times longer than first and second combined; segments 3-10 short, subtriangular; terminal segment subglobular with slightly pointed apex.

Pronotum (PL) 0.69 - 0.77 mm long, widest (PW: 0.88 - 0.92 mm) at base; with complete transversal depression at apical third and small basolateral impressions, with two prescutellar foveae; sublateral carinae absent; lateral margins convex before and after depression, basal angles slightly projected outwards; disc raised with concave sides near base; two tiny depressed dots medially near base; middle portion of base produced posteriorly; basal margin straight on sides, broadly rounded before scutellum. Scutellum subtriangular. Hypomeron narrow, straight. Prosternum extremely short in front of procoxae; prosternal process parallel-sided, apical portion subtriangular. Mesoventrite short with a deep, broad, V-shaped depression for reception of prosternal process. Metaventrite long and wide, slightly depressed along midline; discrimen thin and long, reaching abdomen. Legs slender, long. Procoxae and mesocoxae rounded, metacoxae transverse. Forelegs shortest, with all segments slightly wider than remaining pairs. Mesotibiae with medial pubescent area long, reaching before apex and lateral pubescent area long, extending to 2/3 of tibia. Mesotibiae with short thorn-like carina on inner apex, metatibiae with feeble thorn-like carina on inner apex. Tarsi simple, fourth tarsal segment with fine, nearly erect setae ventrally, fifth segment longest. Tarsal claws long and stout.

Elytra (EL) 2.28 - 2.42 mm long, widest (EW: 1.12 - 1.15 mm) across humeri; subparallel in anterior 4/5, with ten rows of small punctures forming striae; punctures separated by a distance three to four times the puncture diameter; humeral area slightly swollen. First four or five striae distinct, in nearly straight lines, remaining ones feebly visible, obscured apically. Epipleuron thin, widest in anterior third. Apical margin of elytra narrowly rounded.

Abdomen with five clearly visible ventrites (Fig. 12). Intercoxal process subtriangular with rounded apex. First three ventrites depressed medially; fifth ventrite deeply and broadly emarginate. Cuticle densely covered with short, golden, recumbent setae. Aedeagus (Figs 23, 24) elongate. Penis in ventral view narrowing from short basal apophyses towards rounded apex with right margin slightly dilated in middle, in lateral view slender, sinuate, with widened basal fourth; with corona membranous, fibula not visible, curved oblong sclerotized structure present in middle. Parameres slightly longer than half of penis, in lateral view widest at base, moderately tapering towards rounded apex, in ventral view jointed in middle, with rounded apex. Phallobase parallel-sided, curved in lateral view. Penis and parameres with sparse fine spines.

Female. Externally similar to male (Figs 2, 13) except bigger; elytra broader with slightly produced apex; meso - and metatibiae without carina on inner apex; first three ventrites medially convex and fifth ventrite very broadly but shallowly emarginate. Females vary in size (CL: 3.25 - 3.36 mm, PL: 0.70 - 0.71 mm, PW: 0.86 - 0.95 mm, EL: 2.54 - 2.66 mm, EW: 1.14 - 1.26 mm).

Variation. We observed variation in color from dark brown to brown, size and pubescence, especially on abdominal sterna. Scale of green iridescence differed substantially.

Distribution.

Until now, the species was known only from Colombia. We recorded H. cordillierae at two localities in the Napo Province and three localities in Pastaza Province (Fig. 36). This is the first record of H. cordillierae for Ecuador.

Note.

We had habitus and aedaeagus photographs of the type available in this study, and were kindly provided with a redescription by Cinzia Monte, which was made based on the study of the type specimen. Based on the comparison of our specimens with the redescription of H. cordillierae , we have assigned the studied specimens to H. cordillierae .