Hydraena (Hydraenopsis) multivillosa, 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 : 20-22

Hydraena (Hydraenopsis) multivillosa , new species

Figs. 3 (habitus comparison), 11 (habitus and aedeagus)

Type Material. Holotype (male): “ MEXICO: Estado de México, Villa Guerrero, Totolmajac , 16.iv.1990, 18°55’08’’ N, 99°40’54’’W, 2010 m, Arroyito, R. Arce col.” ( IEXA) . Paratype: Same data as holotype (one male IEXA) .

Differential Diagnosis. This new species is a member of the H. leechi Group, H. scintillabella Subgroup , the group of species that have a pronotal scintilla, and the males lack metatibial brushes ( Perkins 1980: 36). Members will key to couplet 23 in Perkins (1980: 67). This species can be recognized by the combination of the pronotum with a very narrow scintilla, the straight and slender tibiae, the posterolateral and posteromedial pronotal foveae very shallow; anterior ½ of disc without shallow transverse impression, the metaventral plaques very small, narrow, straight, very slightly converging toward one another anteriorly, the mesoventral intercoxal process narrow (l/w ca. 5/1), and the aedeagus ( Fig. 11 ). Reliable identifications will require dissection of males and careful examination of the aedeagus. The aedeagus appears to be a mix of the characters found in most H. marginicollis Group species (species which lack a pronotal scintilla) such as the paramere shape, the comparatively narrow main-piece, and the shape of the distal part of the main-piece; however, having very densely setose parameres, suggestive of the H. leechi Group. Apparently, this species is a link between the two groups, reaffirming the position of the H. leechi Group as a derived branch off of the Hydraena (Hydraenopsis) lineage. See also the diagnosis of H. concatenata n. sp., another species indicating the links between the H. leechi and H. marginicollis Groups.

Description. Size: holotype (length/width, mm): body (length to elytral apices) 1.65/0.69; head width 0.39; pronotum 0.38/0.55, PA 0.43, PB 0.47; elytra 1.03/0.69. Habitus as illustrated ( Fig. 11 ). Dorsum brown, palpi testaceous to brown, tip of last palpomere slightly darker. Dorsum of head and pronotum moderately coarsely densely punctate, interstices shining; punctures of frons disc ca. 1–2xef, interstices ca. 0.5–1xpd; punctures of pronotal disc ca. 2–3xef, interstices narrow walls to ca. 1xpd; 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 very narrow; anterolateral pronotal foveae deep, posterolateral and posteromedial very shallow; anterior ½ of disc without 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. 0.5–1xpd, as are interstices between punctures of a row. Apices in dorsal aspect conjointly rounded, in posterior aspect margins not forming shallow angle with one another.

Venter: Mentum very sparsely very densely punctulate, interstices shining; postmentum very finely densely micropunctulate, weakly shining. Genae raised, shining, with posterior ridge laterally, absent in ca. medial 1/5. Ratios of P2 width and plaque shape (P2/w/l/s) ca. 1/0.5/2/5. P1 laminate; median carina sinuate in profile. P2 narrow, l/w ca. 5/1, sides parallel, apex blunt, apex raised slightly above mesoventral intercoxal process. Plaques very small, narrow, straight, very slightly converging toward one another anteriorly, not raised, located at sides of deep median depression. AIS width at straight posterior margin ca. 3x P2. All tibiae straight, slender. Abdominal apex symmetrical; last tergite rounded apically.

Distribution. Currently known only from the type locality.

Etymology. Named in reference to the very hairy aedeagal parameres.

Figures

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

FIGURE 11. Hydraena (Hydraenopsis) multivillosa new species, holotype habitus and aedeagus.