Hydraena longiloba, Perkins, 2017

Perkins, Philip D., 2017, Hydraenidae of Madagascar (Insecta: Coleoptera), Zootaxa 4342 (1), pp. 1-264 : 121-124

Hydraena longiloba , new species

Figs. 108 (habitus), 110 (aedeagus), 280 (map)

Type Material. Holotype (male): Fianarantsoa, Madiorano , springs at the left border of the stream at site (31) (31 = stream crossing the railroad at km 51.2), elev. 650 m, 21° 27' S, 47° 5' E, 18 viii 2001, Gerecke & Goldschmidt (MD 32) ( NMW).

Differential Diagnosis. Somewhat similar in habitus to H. pilotumida , but smaller (ca. 1.62 vs. 2.02 mm), narrower and flatter. The two species differ also in the form of the male metatibiae, the metaventral plaques (narrower and more widely separated in H. longiloba ), and the form of the sixth abdominal ventrite. The aedeagus of H. longiloba , with very long processes, is immediately recognized.

Description. Size: holotype (length/width, mm): body (length to elytral apices) 1.62/0.64; head width 0.38; pronotum 0.41/0.49, PA 0.41, PB 0.42; elytra 0.95/0.64.

Dorsum dark brown to piceous, head darkest; legs dark brown; maxillary palpi dark brown.

Head and pronotum densely moderately coarsely punctate. Pronotal punctures slightly larger than those of head; interstices varying from narrow ridges to ca. 0.5xpd, shining. Mentum sparsely punctulate, shining; postmentum sparsely, more coarsely punctate, interstices shining. Genae roundly raised, medially smooth and shining, without posterior ridge.

Pronotum slightly sinuate laterally, evidently not emarginate between anterior angle and widest part of pronotum; anterior margin straight or slightly rounded behind eyes, very slightly emarginate behind frons; PF1 shallow; PF2 deep, very shallowly, if at all, confluent medially forming weak U-shaped impression; PF3 deep; PF4 shallow.

Elytra weakly arcuate laterally; summit of posterior declivity near distal 2/3; lateral explanate margins moderately wide; serial punctures round, separated by narrow walls to ca. 0.5xpd, slightly larger than pronotal punctures, some punctures random near scutellum. Intervals very narrow, varying from narrow walls to ca. 0.5xpd, very weakly or not at all raised, not forming distinct unbroken straight lines, weakly shining. Apices in dorsal aspect broadly conjointly rounded, in posterior aspect margins forming moderately deep angle with one another.

Ratios of P2 width and plaque shape (P2/w/l/s) ca. 1/1/2/1.5. P1 laminate; median carina sinuate in profile. P2 l/w ca. 2/1, sides parallel, apex blunt and raised slightly above metaventral intercoxal process. Plaques large, widest near midlength, anteriorly and posteriorly rounded, converging slightly anteriorly, slightly raised, located at sides of median depression. Metaventrite with very short longitudinal ridge on each side, extended posteriorly from margin of each mesocoxal cavity. AIS width at arcuate posterior margin ca. 2x P2. Protibia distinctly arcuate, slightly widened at ca. distal ¼. Mesotibia straight, widest at ca. midlength. Metatibia distinctly arcuate, medial margin distinctly widened in distal 0.5, and bearing on widened area large brush of arcuate setae, setal bases at ca. middle of tibia, not on margin of enlarged area. Metafemur lateral margin strongly arcuate, medial margin strongly sinuate.

Abdominal apex with deep apicomedian concavity, upper margin bearing short setae and lower margin asymmetrical, with small produced point off center. Ventrite 5 very finely strigose in median area, patch of short setae on each side of area. Ventrite 6 median area slightly concave, bordered posteriorly by short setae. Etymology. Named in reference to the very long processes of the aedeagus.

Figures

FIGURE 108. Hydraena longiloba, holotype, habitus dorsal, lateral, and ventral.