Hydraena (Hydraenopsis) belilymba, new species Figs. 2 (habitus comparison), 5 (habitus and aedeagus) Type Material. Holotype (male):“ BELIZE: Toledo District, Columbia Forest Reserve, Union Camp, (16°23’53.7’’N, 89°8’34.1’’W), 11–15 viii 2006 // flight intercept traps P. W. Kovarik ” (MCZ). Paratypes (4): Same data as holotype (2 males MCZ); Blue Creek, 30 vi 1981, coll. W. E. Steiner (2 NMNH). Differential Diagnosis. This new species is a member of the H. colymba Complex of the H. marginicollis Group (Perkins 1980: 37). Other members of the complex include H. colymba, H. malkini, H. nevermanni, and H. pontequula (all Perkins 1980), plus H. lagamba and H. lascrucensis (Brojer & Jäch 2011). These species are very similar in dorsal and most ventral characters; reliable determinations require dissection of males. H. belilymba n. sp. can be differentiated from other members of the complex by the combination of the lack of metaventral plaques, and the aedeagal morphology (Fig. 5). Description. Size: holotype (length/width, mm): body (length to elytral apices) 1.47/0.63; head width 0.36; pronotum 0.37/0.48, PA 0.40, PB 0.43; elytra 0.90/0.63. Habitus as illustrated (Fig. 5). Dorsum with head dark brown to black, pronotum with distinctive dark brown macula surrounded by wide testaceous margins, elytra brown, palpi testaceous, tip of last palpomere not darker. Dorsum of head moderately finely moderately sparsely punctulate; pronotum very finely very sparsely punctulate, more sparsely punctulate on macula than on surrounding areas, interstices strongly shining; punctures of frons ca. 1xef, those of pronotal disc slightly smaller, interstices on pronotal disc ca. 2–5xpd or slightly larger; punctures of clypeus very fine, lateral areas microreticulate. Labrum apicomedially excised, free margins weakly upturned. Pronotum with anterior margin weakly emarginate over middle 1/2; anterolateral pronotal fovea moderately deep, other usual foveae absent. Elytra with summit of posterior declivity slightly beyond midlength; lateral explanate margins narrow; on basal 1/3 punctures slightly larger than largest pronotal punctures, punctures becoming gradually smaller toward posterior. Intervals not raised, shining, width ca. 1–2xpd, 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 moderately densely very finely punctulate; postmentum very finely moderately densely micropunctulate. Genae raised, shining, without posterior ridge. P1 laminate; median carina sinuate in profile. P2 moderately narrow, l/w ca. 4/1, sides converging to blunt apex, apex raised slightly above mesoventral intercoxal process. Plaques absent, metaventrite with deep median depression.AIS width at straight posterior margin ca. 3x P2. Protibiae slightly arcuate, inner margin widened inb distal 1/3; meso- and metatibiae slender, straight. Abdominal apex symmetrical; last tergite with apicomedian emargination. Distribution. Currently known only from Belize. Etymology. Named in reference to the geographical distribution and the relationship to H. colymba Perkins, as indicated by the male genitalia.

Published as part of 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), pp. 1-86 in Zootaxa 5367 (1) on pages 10-12, DOI: 10.11646/zootaxa.5367.1.1, http://zenodo.org/record/10145106