Hydraena (Hydraenopsis) guanajuatoensis, 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 : 20

Hydraena (Hydraenopsis) guanajuatoensis , new species

Figs. 3 (habitus comparison), 10 (habitus and aedeagus)

Type Material. Holotype (male): “ MEXICO: Guanajuato, Victoria, Pto de Palmas , 1950 m, 11.viii.1999, 21°24’59’’N, 100°04’60’’W, 1462 m, R. Arce col. 1” ( IEXA) . Paratypes (22): Same data as holotype (15 IEXA) ; Guanajuato, Victoria, Joya Fría , 12.viii.1999. 21.390833 N, - 100.144444 O, 2400 m, R. Arce Col. (7 IEXA) .

Differential Diagnosis. This new species is a member of the H. leechi Subgroup of the H. leechi Group, the group of species that have a pronotal scintilla, and the males having metatibial brushes ( Perkins 1980: 36). Members will key to couplet 5 in Perkins (1980: 65). The species can be recognized by the relatively large size (ca. 2.02 mm), the metaventral plaques very narrow, straight, slightly converging toward one another anteriorly, not raised, the metatibia of males arcuate, gradually increasing in width from base to apex, inner margin with moderately large brush of arcuate setae, and the aedeagus ( Fig. 10 ). Reliable determinations will include dissection of males and careful examination of the aedegus.

Description. Size: holotype (length/width, mm): body (length to elytral apices) 2.02/0.83; head width 0.44; pronotum 0.53/0.66, PA 0.50, PB 0.56; elytra 1.25/0.83. Habitus as illustrated ( Fig. 10 ). Dorsum brown to dark brown, palpi brown, tip of last palpomere darker. Dorsum of head and pronotum coarsely densely punctate, interstices shining; punctures of frons disc ca. 1–2xef, interstices ca. 1–2xpd; punctures of pronotal disc ca. 2–3xef, interstices narrow walls to ca. 2xpd; punctures of clypeus moderately fine, lateral areas microreticulate. Labrum apicomedially excised, free margins weakly upturned. Pronotum with anterior margin weakly emarginate over middle ½, scintilla large; anterolateral, posterolateral and posteromedial pronotal foveae deep; anterior ½ of disc with shallow transverse impression.

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

Venter: Mentum very densely very finely punctulate, interstices weakly shining; postmentum very finely densely micropunctulate. Genae raised, shining, without posterior ridge. Ratios of P2 width and plaque shape (P2/w/l/s) ca. 1/0.25/1/3. P1 laminate; median carina sinuate in profile. P2 l/w ca. 3/1, parallel, apex blunt, apex raised slightly above mesoventral intercoxal process. Plaques very narrow, straight, slightly converging toward one another anteriorly, not raised, located at sides of deep median depression. AIS width at straight posterior margin ca. 2x P2. Pro- and mesotibiae moderately slender, straight. Metatibia arcuate, gradually increasing in width from base to apex, inner margin with moderately large brush of arcuate setae. Abdominal apex symmetrical; last tergite with shallow apicomedian notch.

Distribution. Currently known only from the type locality and one nearby locality.

Etymology. Named in reference to the known geographical distribution.

Figures

FIGURE 3. Dorsal habitus of Hydraena species, H. leechi Group.

FIGURE 10. Hydraena (Hydraenopsis) guanajuatoensis new species, holotype habitus and aedeagus.