Hydraena (Hydraenopsis) pocilla, Perkins, 2023

Perkins, Philip D., 2023, New Neotropical and Nearctic species of water beetles in the genera Hydraena Kugelann and Ochthebius Leach, a key to North American genera and subgenera of the family, new distribution records, and a synopsis of ecology, behavior and morphology related to aquatic life (Coleoptera: Hydraenidae), Zootaxa 5367 (1), pp. 1-86 : 22-24

Hydraena (Hydraenopsis) pocilla , new species

Figs. 2 (habitus comparison), 12 (habitus and aedeagus)

Type Material. Holotype (male): MEXICO: “ Real de Arriba Temescaltepec , Mex. vii 1932 // H. E. Hinton Collector ” ( UKNHM) . Paratypes (22): Same data as holotype (7 UKNHM) ; Estado de México, Villa Guerrero, Totolmajac , 16.iv.1990, 18°55’08’’ N, 99°40’54’’W, 2010 m, Arroyito, R. Arce col. (10 IEXA) ; Estado de México, Temascaltepec, Real de Arriba , 21.iv.2004, 19°02’22’’N, 99°59’58’’W, 1950 m, R. Arce col. (3 IEXA) ; Estado de México, Temascaltepec, camino Chinchotla , 23.iv.2004, 19°03’86’’N, 99°58’54’’W, 2000 m, R. Arce col. (2 IEXA)

Differential Diagnosis. This new species is tentatively placed in the H. marginicollis Group (see Perkins 1980: 69). The dorsal habitus is somewhat suggestive of the H. leechi Group; however, the pronotum has the anterior margin apparently without a scintilla, but this area is impunctate and very smooth. Members of the species are recognized by the combination of the wide lateral explanate margins of the elytra, the narrow metaventral plaques, the widened protibiae of males, and the aedeagus ( Fig. 12 ). Dissection of males and careful examination of the aedeagus will be required for reliable determinations.

Description. Size: holotype (length/width, mm): body (length to elytral apices) 1.60/0.69; head width 0.37; pronotum 0.37/0.51, PA 0.41, PB 0.45; elytra 0.98/0.69. Habitus as illustrated ( Fig. 12 ). Dorsum with head dark brown, pronotum with dark brown very diffusely margined macula surrounded by wide brown margins, elytra brown, palpi testaceous, tip of last palpomere not darker. Dorsum of head and pronotum moderately coarsely moderately densely punctulate, much more sparsely punctulate on macula than on surrounding areas, interstices shining; punctures of frons disc and pronotal disc ca. 2xef, interstices on pronotal disc quite variable, ca. 1–6xpd or slightly larger; punctures of clypeus very fine, lateral areas microreticulate. Labrum apicomedially excised, free margins weakly upturned. Pronotum with anterior margin very weakly emarginate over middle ½, apparently without scintilla, but this area impunctate, very smooth; anterolateral pronotal fovea deep, posterolateral foveae very shallow or absent, posteromedial foveae shallow.

Elytra with summit of posterior declivity slightly beyond midlength; lateral explanate margins wide; on basal 1/3 punctures slightly larger than largest pronotal punctures, punctures becoming gradually smaller toward posterior. Intervals not raised, width ca. 1xpd, as are interstices between punctures of a row. Apices in dorsal aspect conjointly rounded, in posterior aspect margins forming very shallow angle with one another.

Venter: Mentum very sparsely very finely punctulate, shining; postmentum very finely densely micropunctulate in median concavity, surrounding areas smooth, shining. Genae raised, shining, without posterior ridge. Ratios of P2 width and plaque shape (P2/w/l/s) ca. 1/2/4/2. P1 laminate; median carina sinuate in profile. P2 l/w ca. 2/1, sides parallel or very slightly converging toward blunt apex, apex raised slightly above mesoventral intercoxal process. Plaques narrow, wider posteriorly, tapering to point anteriorly, slightly converging toward one another anteriorly, weakly raised, located at sides of deep median depression.AIS width at straight posterior margin ca. 1.5x P2. Protibia slender, straight, very slightly widened on inner margin at ca. distal ¾. Meso- and metatibiae slender, straight.

Distribution. Currently known only from the type locality.

Etymology. Named in reference to the cup-shaped apex of the aedeagus.

Figures

FIGURE 2. Dorsal habitus of Hydraena species.

FIGURE 12. Hydraena (Hydraenopsis) pocilla new species, holotype habitus and aedeagus.