Helobata pantaneira, Clarkson, Bruno, Santos, André Dias Dos & Ferreira-Jr, Nelson, 2016

Clarkson, Bruno, Santos, André Dias Dos & Ferreira-Jr, Nelson, 2016, On Brazilian Helobata Bergroth, 1888 (Coleoptera: Hydrophilidae): description of two new species, new records, and key to species, Zootaxa 4126 (4), pp. 548-562 : 553-555

Helobata pantaneira sp. nov.

(Figs. 7 to 11)

Type material. Holotype (male): “ BRASIL: Mato Grosso, Poconé,/ Transpantaneira, MT-060,/ Km 43, ponte, 29- VII- 2013, 113 m/ alt., 16°38’37.5”S, 56°46’17.7”W / B. Clarkson, B.H.L. Sampaio,/ N. Ferreira-Jr col.” ( DZRJ, Coleoptera 2207 , in ethanol).

Diagnosis. Moderate-sized species (about 4.45 mm in length). Dorsum pale brown with conspicuous dark brown areas (Fig. 7); head and pronotum without metallic sheen (Fig. 7); pronotum with central brown area faintly delimited; elytra with well-defined black spots around scutellum, on humeral humps, on anterior third (interstria 4), on medial portion (interstria 3), and several round, pale spots scattered on elytral disc (Fig. 7); abdominal ventrites medium to dark brown (Fig. 8). Clypeal disc and frons shagreened on interstices of ground punctuation; fine and very short, decumbent setae regularly spread throughout surface; anterior clypeal margin convex, slightly truncate medially (Figs. 7–8); frontoclypeal suture distinct (Fig. 7). Maxillary palpomere 3 longer than palpomere 4. Mentum finely rugose on lateral portions (Fig. 8). Punctures on elytral rows fine, irregularly spaced on rows 9 and 10 (Fig. 7). Posteromedial elevation on mesoventrite semi-trapezoidal, wide, with weakly raised lateral carinae, oblique, convergent and widely distant anteriorly; not strongly connected with the metaventral projection (Fig. 8). Metaventral projection (between mesocoxae) forming a very narrow elevated longitudinal ridge, not strongly connected with, and conspicuously higher than, metaventral medial carina (Fig. 8). Maximum width of phallobase on apical margins; manubrium short and wide, truncated at base. Parameres longer than median lobe; inner margins slightly concave in ventral view; outer margins convex; apex rounded, slightly bent inwards; median lobe with deep apical emargination on dorsal lobule; ventral lobule much shorter than dorsal lobule, not visible in dorsal view; apex rounded, weakly produced ventrally, not visible in lateral view (Figs. 9–11).

Description. Holotype male: total length 4.95 mm; maximum width 2.85 mm; maximum width of head 1.34 mm; elytral length 3.24 mm; maximum width of pronotum 2.20 mm.

Habitus (Figs. 7–8). Body broadly oval, dorsoventrally depressed. Dorsum pale brown with conspicuous dark brown areas. Clypeus pale brown with postero-central dark brown area; frons dark brown. Pronotum with central brown area faintly delimited. Elytra with black spots around scutellum, elongated black spots on humeral humps (interstriae 7 and 8), square black spots on anterior third (interstria 4), elongated black spots on medial portion (striae 2 and 3, interstria 3), and several round, light spots scattered on elytral disc. Antennae, maxillary and labial palpi uniformly medium brown. Ventral side of head and thoracic plates dark brown, abdominal ventrites medium to dark brown. Legs medium brown with pubescent portion on femora dark brown.

Head. Clypeus and frons finely and densely punctate, punctures irregularly shaped, on frons about 3– 4 x smaller than one ommatidium and 2– 3 x width of punctures on clypeus; interstices densely reticulate, shagreened, with fine and very short, decumbent setae regularly spread throughout surface. Anterior clypeal margin convex, slightly truncate medially, rounded laterally (Figs. 7–8); frontoclypeal suture distinct (Fig. 7). Eyes deeply emarginated, interocular distance about 3x width of one eye in dorsal view (Fig. 7). Maxillary palpi longer than maximum width of head (1.3x longer) (Fig. 8); palpomere 1 minute, palpomere 2 conspicuously longer than palpomere 3 and slightly longer than palpomere 4, palpomere 4 asymmetrical with straighter inner face. Labial palpi about half the width of mentum. Mentum wider than long (about 1.5x wider) (Fig. 8); anterior margin strongly bisinuate, with central rounded notch (Fig. 8); surface strongly irregular, finely rugose on lateral portions, with regularly scattered fine setiferous punctures (Fig. 8).

Thorax. Ground microsculptures on pronotum, scutellar shield and elytra densely reticulate, shagreened, with fine and very short, decumbent setae regularly spread throughout surface; punctation on pronotum evenly and densely distributed, fine punctures on pronotal disc irregularly shaped, about 2x the width of those on front (Fig. 7). Scutellar shield subtriangular, rounded posteriorly, longer than wide (Fig. 7). Elytra with ten distinct longitudinal rows of punctures in dorsal view; punctures on rows fine, about the same size of one ommatidium, regularly spaced in rows 1–8, irregularly spaced in rows 9 and 10; punctures on 10th row barely impressed (Fig. 7). Prosternum finely pubescent, convex, not carinate medialy, with irregular surface (Fig. 8). Meso- and metaventrite finely pubescent. Posteromedial elevation on mesoventrite semi-trapezoidal in ventral view, 2.25x longer than wide, with weakly raised lateral carinae, oblique, convergent and widely distant anteriorly; medial portion slightly convex, posteriorly projected between mesocoxae, not strongly connected with the metaventral projection (Fig. 8). Metaventral projection (between mesocoxae) forming a very narrow elevated longitudinal ridge, not strongly connected with, and conspicuously higher than, metaventral medial carina (Fig. 8). Median and hind femora pubescent on basal four-fifths (Fig. 8).

PLATE 2. Figs. 7 to 11. Helobata pantaneira sp. nov. habitus: 7: dorsal view, 8: ventral view; aedeagus: 9: dorsal view, 10: ventral view, 11: lateral view.

Abdomen. Surface of ventrites even, without medial carina, with smooth lateral and posterior margins, evenly and finely pubescent. Ventrite 5 with shallow posteromedial emargination, semi-triangular, somewhat wider than deep, and lined with coarse spine-like setae (Fig. 8). Aedeagus (Figs. 9–11) 1.10 mm long. Phallobase symmetrical, developed, much shorter than apical portion (ca. 0.23x the aedeagus in length), 1.3x wider than long, maximum width on apical margins; manubrium distinct, short and wide, truncated at base, about 0.20x the length of phallobase. Parameres longer than median lobe, inner margins slightly concave in ventral view, outer margins convex, strongly narrowed at apical fifths, apex rounded, slightly bent inwards. Median lobe thick, dorsal lobule with deep apical emargination (ca. 0.3x length of median lobe), ventral lobule much shorter than dorsal lobule (ca. 0.7x length of median lobe), shorter than apical emargination, not visible in dorsal view; apex rounded, weakly produced ventrally, not visible in lateral view.

Etymology. The specific name pantaneira is the gentilic word used to refer to natives of Pantanal biome, which encompasses the type locality.

Distribution. Known only from type locality in Mato Grosso State, Brazil.

Remarks. Based on the original descriptions, the new species can be distinguished from the others by the convex anterior margin of clypeus (substraight and slightly produced anterolaterally in H. corumbaensis , Figs. 12 and 13; sinuate and strongly produced anterolaterally in H. quatipuru , Figs. 20 and 21); by distinct frontoclypeal suture (absent in H. bitriangulata , see Fig. 1c of García 2000); by fine punctures on elytra (thicker in H. perpunctata ; unknown in H. bitriangulata , H. cuivaum , H. lilianae , H. soesilae and H. aschinakiranae ), by straight, laterally oblique carinae of the posteromedial elevation on mesoventrite (sinuate in H. bitriangulata , see Fig. 2f of García 2000; slightly concave anteriorly, strongly divergent posteriorly and almost connected anteriorly in H. cuivaum , see Fig. 2e of García 2000; slightly convex and almost connected anteriorly in H. lilianae , see Fig. 2d of García 2000; convex posteriorly in H. corumbaensis and in H. quatipuru , Figs. 13 and 21); by parameres longer than median lobe (as long as median lobe in H. corumbaensis , unknown in H. bitriangulata ); by the inner margins of parameres concave in ventral view (sinuate in H. amazonensis sp. nov., H. cuivaum , H. confusa , H. cossyphoides , H. corumbaensis , H. lilianae and H. quatipuru , very slightly sinuate in H. larvalis and H. perpunctata , see figs. 5 and 15 of Fernández & Bachmann 1987; unknown in H. aschinakiranae , H. bitriangulata and H. soesilae ); by deep apical emargination on dorsal lobule (shallow in H. amazonensis sp. nov., H. confusa , H. corumbaensis , H. perpunctata , H. quatipuru and H. soesilae ; unknown in H. bitriangulata ); by ventral lobule much shorter than dorsal lobule (as long as dorsal lobule in H. quatipuru , Figs. 22 and 23; and somewhat shorter in H. corumbaensis , Fig. 15; unknown in H. bitriangulata ); by the apex of ventral lobule not visible in dorsal view (visible in H. corumbaensis , H. cuivaum , H. larvalis , H. lilianae and H. quatipuru , unknown in H. aschinakiranae and H. bitriangulata ); and by the apex of ventral lobule weakly produced ventrally (not produced in H. larvalis ; strongly produced in H. amazonensis sp. nov., H. cossyphoides , H. confusa , H. quatipuru ; unknown in H. aschinakiranae , H. bitriangulata , H. cuivaum , H. lilianae and H. soesilae ).