Hexacylloepus iassu, Polizei & Barclay & Bispo, 2020

Polizei, Thiago T. S., Barclay, Maxwell V. L. & Bispo, Pitágoras C., 2020, Hexacylloepus Hinton, 1940 rises again; 18 new species of a neglected genus (Coleoptera: Byrrhoidea: Elmidae), Zootaxa 4819 (1), pp. 6-48 : 20-22

Hexacylloepus iassu sp. nov.

( Fig. 7 A–C)

Type locality: Brazil, Bahia State, Iaçu .

Diagnosis: Antennae with short and thin setae at apex of each antennomere. Frontoclypeal suture convex. Pronotum with a long, deep, narrow impression on disc, reaching the anterior and posterior margins. Hypomera with a belt of tomentum reaching the lateral and anterior margins. Epipleura with tomentum. Tibiae each with a row of setae on distal third; claws with a tooth at base. Abdomen wholly, strongly raised on middle. Male genitalia apex strongly acute; phallobase 3x as long as wide; parameres very thin, reaching half of the penis length; penis very sharp, with anterior half concave, and posterior half pointed.

Description: Male. Body very elongated, subparallel. Light yellow colour. Total length: 1.67 mm. Greatest width: 0.61 mm.

Head: surface with micropunctures. Antenna inserted between the anterior margin of the eyes and the frontoclypeal suture, filiform, with 11 antennomeres each one with a few short, thin setae at apex. Frontoclypeal suture convex. Clypeus 5x as wide as long; anterior margin straight and posterior margin sinuous; surface similar to that of head. Labrum twice as wide as long; antero-lateral angles rounded; surface alutaceous with short, thin setae. Maxillary palpus 4-segmented; terminal palpomere truncated apically. Labial palpus 3-segmented. Mentum and submentum squared. Gula rectangular. Genae covered with tomentum.

Thorax: Pronotum twice as long as wide, arcuate anteriorly; sides sinuate and serrate, posterior margin smooth with two prescutellar foveae ( Fig. 7A ). Surface with micropunctures and very short setae. Sublateral carinae complete, sinuous and raised. A pair of depressions on the middle portion of pronotum, between the sublateral carinae and longitudinal impression ( Fig. 7A ). Longitudinal impression long, narrow and deep on disc, reaching the anterior and posterior margin, wider on middle portion.

Elytra 3x as long as wide; anterior margin arcuate, lateral margin moderately arcuate and serrate; rounded apex ( Fig. 7A ). Humeri prominent. Surface with puncture rows separated from each other by their diameter, with dense short setae. Elytral suture moderately elevated. Carina short and elevated on interval IV, extending from base to 1/5 of the elytral length; sublateral carinae on intervals VI and VIII, extending from base to 3/4 of the elytral length. Epipleura with tomentum ( Fig. 7B ). Hind wings macropterous. Scutellum oval.

Prosternum moderately squared; surface with micropunctures; anterior margin straight; and lateral margin covered with tomentum. Disc depressed. Prosternal process narrow, and beyond the procoxae; lateral margin elevated; apex slightly rounded; disc flat. Notosternal suture slightly sinuous. Hypomera wider posteriorly than anteriorly; lateral margin serrate; surface with micropunctures and with a belt of tomentum reaching the anterior and lateral margin ( Fig. 7B ).

Mesoventrite with a moderate groove to receive the prosternal process. Mesepimeron and mesepisternum covered with tomentum. Metaventrite broad and with a longitudinal medial depression; surface alutaceous with micropunctures, and with sides covered with tomentum.

Legs (except tarsi) covered with punctures and tomentum ( Fig. 7B ). Coxae rounded; trochanter elongated; femora 7x longer than wide, with half of the elytra length; tibiae long and thin, 10x as long as wide, with 2/3 of the elytra length. Profemora larger than meso- and metafemora. Tibiae each with a row of setae in distal 2/3. Tarsi elongate, strongly constricted laterally, with short setae; apical tarsomere longer than the basal four combined. Claws long and thin with a basal tooth.

Abdomen ( Fig. 7B ): five ventrites; as long as wide and strongly raised at middle. Anterior and posterior margins straight on the first and second ventrites; and arcuate on the subsequent ventrites, lateral margins rounded. Surface densely covered with tomentum. Fifth ventrite with the apex rounded and with long setae.

Male genitalia ( Fig. 7C ): (Total length: 0.76 mm. Greatest width: 0.14 mm), symmetrical and narrowed. Phallobase 3x as long as wide, length approximately the same as penis length. Parameres articulated with phallobase, short, and reaching half of the penis length; very thin, 12x as long as wide, with the apex sharp. Penis very sharp, with anterior half slightly sinuous, and posterior half pointed; fibula very thin approximately the same length as the penis.

Female: External morphology similar to male, except disc of the fifth abdominal ventrite has a glabrous, oval groove.

Material examined: 138 specimens.

Distribution: Brazil: Bahia State.

Male holotype: ♂ | Holo- / type | BR-BA-Iaçu / Rio Paraguaçu / 23.III.2012 Light trap / Adolfo Calor leg. | MZSP 35853 (MZSP) .

Paratypes: 137 specimens BR-BA-Iaçu / Rio Paraguaçu / 23.III.2012 Light trap / Adolfo Calor leg. (90 MZSP; 20 NHMUK; 15 SEMK; 12 USNM) (MZSP 35854-35943).

Etymology: iassu is a tribute to the type locality (Iaçu city). In the indigenous language (tupi-guarani) it means “big river”.

Comparative notes: Hexacylloepus iassu sp. nov. resembles H. calori sp. nov. in colour pattern, antenna with long setae, and long legs. However, H. iassu sp. nov. can be differentiated by the presence of a tooth on the tarsal claws, tomentum on the epipleura, frontoclypeal suture convex, and abdominal ventrites covered with tomentum, while in H. calori sp. nov. there is no tooth on the tarsal claws or tomentum on the epipleura, the frontoclypeal suture is straight, and the first abdominal ventrite is without tomentum. The male genitalia are also different: in H. calori sp. nov. the parameres have a tuft of setae at the apex and the penis is constricted in the anterior half; in H. iassu sp. nov. there is no tuft of setae on the parameres and the penis is markedly acute, with the anterior half slightly sinuous, and posterior half pointed.

Figures

FIGURE 7. Hexacylloepus iassu sp. nov.. Male. Holotype. (A–B) Habitus. (A) Dorsal view. (B) Ventral view. (C) Ventral view of male genitalia. Scale bars: (A–B) = 0.5mm. (C) = 0.1mm.