Hydraena punctilata, Perkins, Philip D., 2011

Perkins, Philip D., 2011, New records and description of fifty-four new species of aquatic beetles in the genus Hydraena Kugelann from South America (Coleoptera: Hydraenidae), Zootaxa 3074, pp. 1-198 : 17-18

Hydraena punctilata , new species

Figs. 7 (habitus), 14 (aedeagus), 193 (map)

Type Material. Holotype (male): Brazil, Amazonas, Est. [Estirao] Do Ecuador, 1 x 1973, M. Alvarenga. Deposited in the MCZ.

Differential Diagnosis. Somewhat similar in dorsal habitus to H. paeminosa ( Figs. 3 , 7 ); differentiated therefrom by the slightly larger size (length ca. 1.76 mm vs. 1.65 mm), the more transverse pronotum (length/width ca. 0.69 vs. 0.82), the coarser pronotal punctation, and the greater degree of randomness of the elytra punctures. In addition, the hind tibiae of males are markedly arcuate in H. punctilata , and straight in H. paeminosa . The pronotal punctation is as coarse as H. neblina ( Fig. 8 ), but the body form is much different in the two species. The male genitalia of the these three species markedly differ in many characters ( Figs. 9, 10, 14). The holotype is very fragmentary; as a result, the positions of the elytra in Fig. 7 are not natural.

Description. Size: holotype (length/width, mm): body (length to elytral apices) 1.76/0.87; head 0.26/0.41; pronotum 0.40/0.58, PA 0.46, PB 0.54; elytra 1.15/0.87. Dorsum of head with frons piceous, clypeus brown; pronotum dark brown to piceous, except grading to brown at margins; elytra dark brown; legs brown; maxillary palpi brown, tip missing.

Dorsum of head microreticulate, dull. Frons very coarsely densely punctate, punctures ca. 5–7xef, interstices ca. 0.5xpd to narrow walls. Clypeus punctures obsolete. Mentum and postmentum microreticulate, dull; postmentum rather coarsely punctate. Genae raised in posterior ridge, except medially.

Pronotum and elytra coarsely densely punctate, subscabrous, each puncture with distinctive, short seta, interstices microreticulate on pronotum. Pronotum with median 1/3 of anterior margin emarginate, except middle are very slightly produced and with very narrow hyaline border; scintilla absent; PF1 absent; PF2 very shallow, almost imperceptible; PF3 and PF4 deep, confluent, separated from lateral margin by low irregular ridge. Elytra quite convex at summit of posterior declivity, slightly past midlength; lateral explanate margins wide; punctures random; interstices irregular surfaces, weakly shining. Apices in dorsal aspect weakly separately rounded, shape in posterior aspect uncertain (elytra are detached).

Ratios of P2 width and plaque shape (P2/w/l/s) ca. x/2 /8/4. P1 slightly wider than laminate; median carina sinuate in profile. P2 tapering to sharp point, tip contiguous with low median carina of metaventrite. Plaques moderately wide posteriorly, tapering to point anteriorly, narrowly separated, very slightly convergent anteriorly, almost parallel, weakly raised, located at sides of shallow median depression. Metaventrite with median carina in anterior 1/2, continued posteriorly to between anterior part of plaques, also with short point on each side, extended posteriorly from margin of each mesocoxal cavity. AIS slightly concave, width at straight posterior margin ca. equal plaque separation. Pro- and mesotibia very slightly arcuate, moderately slender. Metatibia distinctively arcuate in distal 1/2. Male abdominal apex symmetrical; last tergite with posterior 1/2 slightly upturned, free margin rounded. Females not yet known.

Etymology. Named in reference to the wide body form and coarse dorsal punctation.

Distribution. Currently known only from the type locality ( Fig. 193 ).

Note. My attempts to glue the elytra to the body, in a natural position, before imaging were not entirely successful ( Fig. 7 ).

Figures

FIGURE 3. Hydraena paeminosa, holotype, dorsal and lateral habitus, and venter.

FIGURE 7. Hydraena punctilata, holotype, dorsal and lateral habitus, and venter.

FIGURE 8. Hydraena neblina, holotype, dorsal and lateral habitus, and venter.

FIGURES 193 – 194. 193. Geographical distributions of species in the Paeminosa Group. 194. Geographical distributions of species in the Curvosa and Multispina Groups.