Hemiosus santosi, Clarkson, Bruno & Ferreira-Jr, Nelson, 2009

Clarkson, Bruno & Ferreira-Jr, Nelson, 2009, Three new species of Hemiosus Sharp (Coleoptera: Hydrophilidae) and new state records of Hemiosus fittkaui Oliva and H. moreirai d’Orchymont from Brazil, Zootaxa 2139, pp. 61-68 : 64-67

Hemiosus santosi , sp. nov.:

(Fig. 7–12)

Type Material. Holotype 3, DZRJ: ( Coleoptera 2594 ), “ BRASIL: Minas Gerais,/ Lima Duarte, Parque/ Estadual do Ibitipoca,/ Lago dos Espelhos,/ 05.VIII.1997, folhiço de/ fundo,-21.697243°, -43.879448°,/ C. N. Francischetti leg.”; Paratype 4 Ƥ, DZRJ: ( Coleoptera 1820 ), “ BRASIL: Minas Gerais, Lima/ Duarte, Parque Estadu-/ al do Ibitipoca, Lago/ dos Espelhos, folhiço/ de fundo, 05.VIII.1997,/ -21.697243°, -43.879448°,/ C. N. Francischetti leg.”; 13 1Ƥ, DZRJ: ( Coleoptera 1611 ), “ BRASIL: Minas Gerais,/ Lima Duarte, Parque/ Estadual do Ibitipoca,/ Cachoeirinha,/ 08.IX.2000,/ -21.680875°, -43.882696°,/ C. N. Francischetti leg.”

Diagnosis. Dorsal surface brown with melanic and testaceous areas, lateral edges of pronotum and humeral humps testaceous. Elytra (Fig. 7) each with interstria 9 very slightly raised from posterior half of its length to the intersection with interstria 11; interstria 10 strongly raised in anterior part, even under humeral hump; interstria 11 slightly raised. Mesosternal process (Figs. 8, 9) broad; with raised anterior tooth followed by a shorter tooth and pair of lateral slightly raised teeth; metasternal process (Fig. 8) straight; anterior carina less strongly raised than the mesosternal process. Ventrite V (Fig. 10) apical notch with short median triangular tooth and pair of lateral smaller teeth. Male genitalia (Figs. 11, 12) with median lobe shorter than paramera; appendices acuminate and shorter than median lobe, weakly separated; paramera very acuminate; basal piece longer than distal piece, sclerotised, asymmetrical in basal two-fifths.

Description. Holotype male: total length 3.36 mm; maximum width 1.76 mm; maximum length of the head 0.62 mm; elytral length 2.56 mm; maximum width of the pronotum 1.19 mm.

Head, pronotum and scutellum without metallic sheen. Head melanic. Pronotum brown with melanic areas on anterior and posterior margins, lateral margins lighter (on whole specimens these areas appearing testaceous). Elytra brown, distal quarter lighter, humeral humps lighter, same diffuse lighter spots laterally. Apical maxillary palpomeres dark on apical two-fifths, with light-colored tip. Sternites and legs brown.

Head, pronotum, and scutellum punctulate. Head densely covered with punctures; profile flattened; labrum narrow, directed downwards; apical maxillary palpomeres short and round. Pronotum densely covered with punctures, lateral portions with larger punctures (about twice as big as those on head and pronotum disk); median line without punctures; posterolateral pits shallow, 2–3 times the size of lateral punctures; lateral margins depressed and crenulate, anterior angles coarsely crenulated. Elytra (Fig. 7) with punctures much larger than pronotal ones; scutellar stria developed with deep punctures; inner interstriae wide and flat, about 3 times as wide as striae, with row of very small punctures; outer interstriae narrow and convex; interstria 9 very slightly raised from half of its length to intersection with interstria 11; interstria 10 strongly raised in the anterior two-thirds, even under humeral hump; interstria 11 slightly raised throughout its length; lateral margin of elytron with deep and very coarse punctures. Mesosternal process (Fig. 8) in ventral view broad especially on anterior third, with median depression; pair of lateral teeth on anterior third of process; in lateral view (Fig. 9) with raised anterior tooth followed by a shorter tooth; posterior half elevated and slanting posteriorly on posterior third. Metasternal process (Fig. 8) straight; anterior carina flat, on a lower plane than mesosternal process; posterior edge of process produced and blunt; posterolateral margins slightly produced posteriorly. Legs with middle and hind femora with extensive pubescence, about four-fifths of its length. Ventrite I (Fig. 10) with narrow flat medial carina, continuously broadening posteriorly and reaching posterior margin of sternite; produced and raised in anterior part; slanting posteriorly; lateral carinae flat and narrow, about two-thirds length of sternite, curved mesally. Ventrites II to IV with flat basal carinae, which do not reach the posterior margin of sternites. Ventrite V apical notch with short median triangular tooth and pair of lateral smaller teeth; lateral margins very finely crenulate. Male genitalia (Figs. 11, 12) with median lobe shorter than paramera, subcylindrical and blunt, visible in ventral view; appendices acuminate and shorter than median lobe, separated for most of their visible length; paramera very acuminate, slightly narrowed in apical three-fifths, tips turned inwardly; basal piece about three-fifths of whole organ, strongly sclerotised, about twice as long as wide; asymmetrical in basal two-fifths.

PLATE 2. Fig. 7–12. Hemiosus santosi , sp. nov., 7: left elytron in dorsal view: colour pattern, interstriae 9 and 11 slightly raised, interstria 10 raised under the humeral hump; 8: mesosternal and metasternal process in ventral view; 9: mesosternal process and anterior part of metasternal process in lateral view; 10: apparent ventrites in ventral view: median and lateral carinae, apical notch; 11: male genitalia in ventral view; 12: male genitalia in lateral view. Scale on figs. 7 and 10 = 1.0 mm, others = 0.5 mm.

Etymology. This species is dedicated to Msc. André Dias dos Santos, who determined the type-material as an undescribed species, and firstly showed the first author the way into the “Hydrophiloidea knowledge world”.

Taxonomic notes. The new species may be distinguished from other Hemiosus by a combination of characteristics from the shape of the male genitalia, mesosternal, and metasternal processes. Although the genitalia of H. santosi sp. nov. is similar to that of H. ater sp. nov., they can be easily separated by their proportions. Hemiosus santosi has median lobe much shorter than paramera; appendices separated through their visible length; more acuminate and gradually narrowing paramera, and basal piece longer than distal piece. The dorsal coloration may also help distinguish H. santosi ; it is more brown than testaceous, it does not have a metallic sheen, and its humeral humps are remarkably testaceous. Another interesting character is the additional lateral projections on the apical notch of the fifth ventrite besides the median triangular tooth. Other characteristics are mentioned above in H. ater taxonomic notes.

Hemiosus frades , sp. nov.: (Figs. 13–18)

Type Material. Holotype 3, DZRJ: ( Coleoptera 1262 ), BRASIL: Rio de Janeiro,/ Teresópolis, Rio dos/ Frades , 18.V.1991,/ -22.340408°, -42.811028°,/ pedra, raspagem, remanso,/ E. R. da Silva & J. L. Nessimian leg.; Paratype 6 Ƥ, DZRJ: ( Coleoptera 1307 ), BRASIL: Rio de Janeiro,/ Teresópolis, Rio dos/ Frades , 19.V.1991,/ -22.340408°, -42.811028°,/ poças em pedra, E. R. da Silva & J. L. Nessimian leg.

Diagnosis. Profile flattened; labrum broad, directed downwards. Elytra each with scutellar stria obsolete; apex produced posteriorly on females, with two distal teeth (Fig. 13). Mesosternal process (Figs. 14, 15) narrow; obsolete anterior tooth followed by a strong bulge and a weakly raised plateau; metasternal process (Fig. 14) narrow; carina raised on anterior part; posterior part of process produced and acuminate. Legs with fore claws of male sickle-shaped. Ventrite I (Fig. 16) with fine Y-shaped carina lowered on posterior end; lateral carinae narrow, narrowed backwards, curved inwards. Male genitalia (Figs. 17, 18) with median lobe shorter than paramera; apex rounded; appendices not seen; paramera acuminate; basal piece strongly curved.

Description. Holotype male: total length 2.72 mm; maximum width 1.31 mm; maximum length of the head 0.69 mm; elytral length 1.92 mm; maximum width of the pronotum 0.87 mm.

PLATE 3. Fig. 13–18. Hemiosus frades , sp. nov., 13: apical quarter of elytra: apices produced in females; 14: mesosternal and metasternal process in ventral view; 15: mesosternal process and anterior part of metasternal process in lateral view; 16: apparent ventrites in ventral view, median and lateral carinae, apical notch; 17: male genitalia in ventral view; 18: male genitalia in lateral view. Scale = 0.5 mm.

Head melanic with metallic sheen. Pronotum yellow with large median, triangular melanic area, melanic with metallic sheen. Scutellum and elytra yellow. Elytra with brown punctures and each elytron with two small brown spots in median region, one near the elytral stria and another on outer margin (over striae 8 to 11). Femora yellow. Apical maxillary palpomeres dark on apical half, with light-colored tip. Sternites brown.

Head, pronotum, and scutellum not punctulate. Head densely covered with small punctures; profile flattened; labrum broad, directed downwards; apical maxillary palpomeres short and thick. Pronotum densely covered with deep punctures as large as those on frons; lateral margins with large punctures, about twice the size of other punctures on head and pronotum; median line without punctures; posterolateral pits deep, twice the size of lateral punctures; lateral margins depressed and finely crenulate; Scutellum with some fine punctures. Elytra with scutellar stria obsolete, marked by punctures as large as pronotal ones, strongly separated from each other; striae punctures a little coarser, separated by their diameter; inner interstriae wide and flat, about 3–4 times as wide as striae; outer interstriae flat, about 3 times as wide as striae; punctures on inner interstriae nearly as large as those on striae, absent on interstriae of striae 8–11; apices produced shallowly emarginate, bispinous in females (Fig. 13). Mesosternal process (Fig. 14) in ventral view narrow in lateral view (Fig. 15) with obsolete anterior tooth followed by strong bulge and weakly raised plateau; posterior third slanting posteriorly. Metasternal process (Fig. 14) narrow; anterior carina raised on anterior part, strong slanting posteriorly; posterior part of process produced and acuminate; posterolateral corners weakly produced. Legs with fore tarsi of male with three basal tarsomere hairs, second one slightly swollen; fore claws of male sickle-shaped, remaining ones weakly arched; Legs with middle and hind femora with extensive pubescence, about four-fifths of its length. Ventrite I (Fig. 16) with fine Y-shaped carina lowered on posterior end, not reaching posterior margin of sternite; lateral carinae narrow, narrowing posteriorly, curved inwardly, about half length of sternite. Ventrite II to IV without carinae. Ventrite V apical notch broad and straight, weakly arched; lateral margins smooth. Male genitalia (Figs. 17, 18) narrow in ventral view; median lobe shorter than paramera, subcylindrical, apex rounded; appendices not visible; paramera gradually acuminate, apices turned inwardly; basal piece strongly curved, about 1.5 times longer and narrower than distal one; asymmetrical in basal sixth.

Etymology: The specific name is a reference to the Frades river from where the type-specimens were collected.

Taxonomic notes. The new species may be distinguished from other Hemiosus by a combination of characteristics from the shape of the mesosternal and metasternal processes and the male genitalia. The male genitalia are fairly similar to that of H. montrosus Oliva in that their genitalia are not as flattened as in other species, making it difficult to open up the distal pieces without damage, and the appendices are not apparent. The male genitalia of H. frades can be distinguished from H. monstrosus by its shorter and more strongly curved basal piece. Moreover, H. frades has others characters shared with H. monstrosus , such as, the flattened head profile, the broad labrum and the elytral apices produced. Of those Hemiosus species occurring in Brazil, only H. monstrosus shows produced elytral apices, those being triangular and occurring in both sexes.