Hydraena pentarubra, Perkins, 2017

Perkins, Philip D., 2017, Hydraenidae of Madagascar (Insecta: Coleoptera), Zootaxa 4342 (1), pp. 1-264 : 95-97

Hydraena pentarubra , new species

Figs. 85 (habitus), 87 (aedeagus), 268 (map)

Type Material. Holotype (male): Antsiranana, Montagne d'Ambre, Grande Cascade , main channel, elev. 740 m, 13° 34' S, 49° 10' E, 1 xi–30 xii 2004, M. Balke & D. Ottke (MD 006) ( ZSMC) . Paratypes (226): Antananarivo, Nosy Be, Réserve Naturelle Intégrale de Lokobe, 6.3 km 112° ESE Hellville , sifted litter in rainforest, elev. 30 m, 13° 25' S, 48° 19' E, 19–24 iii 2001, Fisher, Griswold et al. (BLF 3422) (1 CAS) ; Antsiranana, Joffreville (M.d'Ambre), first right affl. below Grande Cascade, in steep forest valley, elev. 1154 m, 12° 30' S, 49° 10' E, 26 iii 2011, R. Gerecke (MD 186) (7 NMW); Joffreville (M.d'Ambre), R.Antomboka downstr. large cascade, elev. 850 m, 12° 32' S, 49° 10' E, 12 xi 2001, Gerecke & Goldschmidt (MD 165) (14 NMW); Montagne d'Ambre, Grande Cascade, elev. 740 m, 13° 34' S, 49° 10' E, 1 xi–31 xii 2004, M. Balke (MD 003) (1 ZSMC); Same data except (MD 004), (3 ZSMC; one male " MNCN AI-542 DNA specimen"); Montagne d'Ambre, Grande Cascade, main channel, elev. 740 m, 13° 34' S, 49° 10' E, 1 xi–30 xii 2004, M. Balke & D. Ottke (MD 006) (33 ZSMC); Mt. Ambre, 0.5 km NE N.P. campsite, elev. 1000 m, 12° 31' S, 49° 10' E, 1 iii 2003, G. Cuccodoro (4a) (1 MHNG); Mt. Ambre , 1 km NW N.P. camp site, elev. 1000 m, 12° 31' S, 49° 10' E, 2 iii 2003, G. Cuccodoro (5) (5 MHNG); Mt. Ambre , 1.5 km NE N.P. camp site, elev. 950 m, 12° 32' S, 49° 10' E, 1 iii 2003, G. Cuccodoro (4b) (3 MHNG); Mt. Ambre , 2.5 km SE N.P. camp site, elev. 1000 m, 12° 31' S, 49° 11' E, 11 iii 2003, G. Cuccodoro (12a) (3 MHNG); Mt. Ambre , 3 km NE N.P. camp site, elev. 1300 m, 12° 33' S, 49° 9' E, 28 ii 2003, G. Cuccodoro (3a) (121 MHNG), (15a) (4 MHNG); Parc National Montagne d'Ambre , 12.2 km 211° SSW Joffreville , sifted litter in montane rainforest, elev. 1300 m, 12° 35' S, 49° 9' E, 2–7 ii 2001, Fisher, Griswold et al. (BLF 2808) (3 CAS); Parc National Montagne d'Ambre , 3.6 km 235° SW Joffreville, sifted litter, montane rainforest, elev. 925 m, 12° 32' S, 49° 10' E, 20–26 i 2001, Fisher, Griswold et al. (BLF 2564) (20 CAS); Parc National Montagne d’Ambre , malaise trap MA-01-01A-09, elev. 960 m, 12° 30' S, 49° 10' E, 19 iii–5 iv 2001, R. Harin’Hala (3 CAS).

Differential Diagnosis. The smallest member of the species group (ca. 1.48 mm); differentiated by the comparatively short elytra and the very narrow, subcarinate, metaventral plaques, which are widely separated. The aedeagus is immediately distinguished from other members of the group by the shape of the distal piece and the wide apex of the paramere.

Description. Size: holotype (length/width, mm): body (length to elytral apices) 1.48/0.68; head width 0.39; pronotum 0.34/0.55, PA 0.43, PB 0.45; elytra 0.94/0.68.

Dorsum reddish brown, head and elytra darker than pronotum; elytral epipleurs lighter than venter; legs brown; maxillary palpi testaceous, distal ½ of last palpomere not darker.

Head and pronotum moderately finely punctate. Pronotal punctures distinctly smaller on disc than anteriorly and posteriorly; interstices on disc ca. 2xpd, ca. 1xpd anteriorly and posteriorly, shining. Mentum finely sparsely punctulate, shining; postmentum densely punctate medially. Genae raised, shining, with posterior ridge, interrupted in midline.

Pronotum arcuate laterally; anterior margin straight behind eyes, emarginate behind frons; PF1 and PF2 absent; PF3 and PF4 very shallow.

Elytra weakly arcuate laterally; summit of posterior declivity at ca. midlength; lateral explanate margins wide; serial punctures slightly rectangular, separated by ca. 1xpd, as large as largest pronotal punctures, some punctures random near scutellum. Intervals not raised, shining, ca. 1– 2x puncture width. Apices in dorsal aspect moderately broadly conjointly rounded, in posterior aspect margins not forming angle with one another.

Ratios of P2 width and plaque shape (P2/w/l/s) ca. 1/0.5/1.3/1.5. P1 as wide as P2; median carina weakly sinuate in profile. P2 l/w ca. 2/1, sides parallel, apex blunt and on same level as anteromedian carina of metaventrite. Plaques narrow, elongate, widely separated, very slightly raised, located at sides of median depression. Metaventrite anteromedian carina ca. as long as plaques, not quite attaining anterior level of plaques, forking in low ridge to join plaques, together with plaques forming inverted Y-shape; short longitudinal ridge on each side, extended posteriorly from margin of each mesocoxal cavity. AIS width at arcuate posterior margin ca. 1.5x P2. Protibia medial margin straight, lateral margin very weakly arcuate. Mesotibia straight, widest near midlength, medial margin notched in distal ¼ and here bearing 4 short sharp spines. Metatibia straight, moderately wide. Metafemur more strongly arcuate on lateral than medial margin. Abdominal apex with narrow apicomedian notch.

Etymology. Named in reference to the five longitudinal ridges of the mesoventrite, and to the reddish color.

Figures

FIGURE 85. Hydraena pentarubra, holotype, habitus dorsal, lateral, and ventral.