Hexacylloepus geiseri, 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 : 16-18

Hexacylloepus geiseri sp. nov.

( Fig. 5 A–C)

Type locality: Brazil, Santa Catarina State, Seara, Nova Teutônia .

Diagnosis: Antenna with long and thin setae at apex of each antennomere. Frontoclypeal suture inconspicuous. Pronotum with a long, narrow longitudinal impression on disc. Hypomera with a short belt of tomentum reaching only the portion near to notosternal suture. Epipleura without tomentum. Protibiae each with a row of spines on 2/3 of distal half. Meso- and metatibiae each with a complete row of long setae and a row of short spines. Abdomen with the disc of the first ventrite without tomentum and the fifth ventrite with lateral margins slightly produced posterolaterad. Male genitalia acute; phallobase 3x as long as wide; parameres reaching 2/3 of the penis length, moderately curved toward internal margin, apex acute, with a tuft of long and thin setae; penis with anterior portion moderately constricted and the lateral margin straight, median portion expanded, and apex acute.

Description: Male. Body elongated, subparallel. Black colour, with the antenna, mouthparts and legs reddishbrown. Total length: 2.12 mm. Greatest width: 1.05 mm.

Head: surface with micropunctures separated from each other by their diameter. Antenna inserted on the anterior margin of the eyes, filiform, with 11 antennomeres each one with long thin setae at apex. Frontoclypeal suture inconspicuous. Clypeus 3x 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 and alutaceous; surface with long, thin setae. Maxillary palpus 4-segmented; terminal palpomere truncated apically. Labial palpus 3-segmented. Mentum wide and flat, submentum square. Gula rectangular. Genae covered with tomentum.

Thorax: Pronotum as long as wide, arcuate anteriorly and laterally; posterior margin smooth with two prescutellar foveae ( Fig. 5A ). Surface with micropunctures. Sublateral carinae complete, sinuous and raised ( Fig. 5A ). Longitudinal impression long, shallow and narrow on disc, reaching the anterior and posterior margins; and wider on middle.

Elytra moderately longer than wide; anterior margin arcuate; lateral margin moderately arcuate and serrate; rounded apex ( Fig. 5A ). Humeri rounded and prominent. Surface with punctures. Elytral suture moderately elevated. Carina short and elevated on interval IV, extending from base to 1/4 of the elytral length; sublateral carinae on intervals VI and VIII, extending from base to 2/3 of the elytral length. Epipleura with tomentum ( Fig. 5B ). Hind wings macropterous. Scutellum large and oval.

Prosternum broad, strongly elevated anteriorly, surface with micropunctures; anterior margin straight and lateral margin covered with tomentum. Prosternal process narrow and beyond the procoxae; lateral margin elevated; rounded apex; disc depressed. Notosternal suture sinuous. Hypomera wider posteriorly than anteriorly, lateral margin serrate surface, with micropunctures and with a short belt of tomentum reaching only the portion near to notosternal suture ( Fig. 5B ).

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

Legs (except tarsi) covered with punctures and tomentum ( Fig. 5B ). Coxae rounded; trochanter elongated; femora 3x as long as wide, 1/3 of the length of the elytra; tibiae long and thin, 7x longer than wide, 1/3 of the length of the elytra. Protibiae each with a row of spines on 2/3 of distal half. Meso- and metatibiae each with a complete row of long setae and a row of short spines. Tarsi elongate, with setae basally; apical tarsomere with the length of the basal four combined. Claws long and thin.

Abdomen ( Fig. 5B ): five ventrites; as long as wide. Anterior and posterior margins straight on the first and second ventrites and arcuate on the subsequent ventrites, lateral margins rounded. Surface covered with tomentum (excepted for disc of first ventrite). Disc of the first ventrite with the anterior margin raised. Fifth ventrite with lateral margins slightly produced posterolaterad, and the apex rounded.

Male genitalia ( Fig. 5C ): (Total length: 0.86 mm Greatest width: 0.22 mm), symmetrical and acute. Phallobase 3x as long as wide, twice as long as penis length. Parameres articulated with the phallobase, reaching 2/3 of the penis length; moderately curved to internal margin; acute apex with a tuft of long and thin setae. Penis with anterior portion moderately constricted and with lateral margin sinuous; median portion with an expansion and apex acute; fibula elongate, approximately half of the penis length, and with tapered toward the apex; corona present, arrangement of tiny rod-like sclerotizations.

Female: External morphology similar to male, except the disc of the metaventrite with micropunctures and setae.

Material examined: 119 specimens.

Male holotype: N. Teutonia / Braz. 1972 / F. Plaumann | H.E.Hinton / collection. / B.M.1977-566 . | ♂ | Holo- / type ( NHMUK)

Paratypes: 118 specimens: N. Teutonia / Braz. 1972 / F. Plaumann | H.E.Hinton / collection. / B.M.1977-566. (20 ♂ 20 ♀ NHMUK; 5 ♂ 10 ♀ MZSP; 5 ♂ 10 ♀ USNM). BRASIL. São Paulo. Campos do / Jordão. Parque Estadual Campos / do Jordão. I.2006 Riacho / Celestina. Spies & Gorni leg. (7 MZSP). (MZSP 31166-31169, 35716-35722, 35724-35730, 35734). BRASIL. São Paulo, Ribeirão / Grande. Parque Estadual / Intervales. Ribeirão Mirante. / 18.IX.2005 Pitágoras Bispo leg. (20 MZSP; 12 NHMUK; 6 USNM; 6 SEMK). (MZSP 31344-31363) .

Distribution: Brazil: Rio de Janeiro, São Paulo, Santa Catarina, and Rio Grande do Sul, States.

Etymology: geiseri is a tribute to Dr. Michael Geiser, curator of the Coleoptera collection at NHMUK.

Comparative notes: Hexacylloepus geiseri sp. nov. is similar to H. plaumanni by having the frontoclypeal suture inconspicuous; pronotal disc with a long and narrow longitudinal impression; Hypomera with a short belt of tomentum reaching only the portion near to notosternal suture and same pattern of sexual dimorphism. However, the male genitalia is different: in H. geiseri sp. nov. the penis has the anterior portion moderately constricted, with lateral margin sinuous, and the median portion with an expansion, while in H. plaumanni the penis has the lateral margin straight and is moderately constricted at the base.

Figures

FIGURE 5. Hexacylloepus geiseri 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.