Hydraena (Hydraenopsis) concatenata, 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 : 17

Hydraena (Hydraenopsis) concatenata , new species

Figs. 3 (habitus comparison), 9 (habitus and aedeagus)

Type Material. Holotype (male): “ MEXICO: Veracruz, Los Tuxtlas area nr. Balzapote , 15 v 1981, coll. P. J. Spangler ” ( NMNH) . Paratype: Same data as holotype (1 female NMNH) .

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 scintilla, the pronotal foveae deep, the metaventral plaques very narrow, very indistinct or absent, and the unusual aedeagus ( Fig. 9 ). 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 and paramere setation, but with the robustness of the lateral shape, and the distal shape of the main-piece indicating 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. multivilosa 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) 1.67/0.71; head width 0.40; pronotum 0.43/0.58, PA 0.45, PB 0.49; elytra 1.00/0.71. Habitus as illustrated ( Fig. 9 ). Dorsum with head dark brown to black, pronotum with dark brown very diffusely margined disc surrounded by wide brown margins, elytra brown, maxillary palpi missing from specimen. Dorsum of head and pronotum moderately finely moderately densely punctulate, more sparsely punctulate on pronotal disc than on surrounding areas, interstices shining; punctures of frons disc ca. 1–2xef, interstices ca. 1xpd; punctures of clypeus very fine, lateral areas microreticulate. Punctures of pronotal disc ca. 2–3xef, interstices on pronotal disc quite variable, ca. 1–3xpd. Labrum apicomedially excised, free margins weakly upturned. Pronotum with anterior margin emarginate over middle ½, with scintilla; antero- and posterolateral pronotal fovea deep, posteromedial foveae moderately deep; disc anteriorly with shallow transverse impression.

Elytra with summit of posterior declivity slightly beyond midlength; lateral explanate margins wide; on basal 1/3 punctures ca. 1xpd of largest pronotal punctures, punctures becoming gradually smaller toward posterior. Each puncture with fine short recumbent seta. 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 shallow angle with one another.

Venter: Mentum sparsely very finely punctulate, shining; postmentum very finely densely micropunctulate in median concavity, surrounding areas smooth, shining. Genae raised, shining, posterior margin slightly raised laterally. P1 laminate; median carina sinuate in profile. P2 l/w ca. 3/1, sides slightly converging toward blunt apex, apex raised slightly above mesoventral intercoxal process. Plaques very narrow, very indistinct or absent, located at sides of deep median depression. AIS width at straight posterior margin ca. 3x P2. Pro- and meso tibiae slender, straight. Metatibia very slightly arcuate, gradually slightly increasing in width from base to apex. Abdominal apex symmetrical; last tergite with very shallow apicomedian notch.

Distribution. Currently known only from the type locality.

Etymology. Named in reference to the aedeagal morphology, which appears to represent a linking form between the H. leechi Group and the H. marginicollis Group of Hydraena .

Figures

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

FIGURE 9. Hydraena (Hydraenopsis) concatenata new species, holotype habitus and aedeagus.