Reclassification of Cybistrinae Sharp, 1880 in the Neotropical Region (Coleoptera, Adephaga, Dytiscidae), with description of new taxa Author Miller, Kelly B. https://orcid.org/0009-0004-1093-4066 Department of Biology and Museum of Southwestern Biology, University of New Mexico, Albuquerque, NM 87131 - 0001, USA kbmiller@unm.edu Author Michat, Mariano C. https://orcid.org/0000-0002-1962-7976 Instituto de Biodiversidad y Biologia Experimental y Aplicada, CONICET-Universidad de Buenos Aires, Buenos Aires, Argentina Author Ferreira Jr, Nelson https://orcid.org/0000-0002-5932-7695 Laboratorio de Entomologia, Departamento de Zoologia, Instituto de Biologia, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brasi text ZooKeys 2024 2024-01-08 1188 125 168 http://dx.doi.org/10.3897/zookeys.1188.110081 journal article http://dx.doi.org/10.3897/zookeys.1188.110081 1313-2970-1188-125 997ADB92AFA7497982A2B81C00EF3AEA FD00287A8052513C815877D5359D01A1 Megadytes parvus ( Tremouilles , 1984) comb. nov. Figs 12 , 23 , 24 , 39-43 , 55 Cybister parvus Tremouilles , 1984: 187. Type locality. Brazil, Bahia State, Santa Rita. Type specimens. Holotype and nine paratypes in Museu de Zoologia, Universidade de Sao Paulo, Brazil and two paratypes, one male and one female, in Museo de La Plata, La Plata, Argentina. Diagnosis. This species differs from the other species in the genus, M. latus , in smaller size (TL = 13.0-14.6 mm), narrower shape (TL/GW = 1.9-2.1) (Fig. 12 ) and features of the male genitalia (Figs 39-43 ). See above under M. latus for details about these differences between the two species. Description. Measurements . TL = 13.0-14.6 mm, GW = 6.2-7.7 mm, PW = 5.4-5.9 mm, HW = 3.3-3.4 mm, EW = 2.0-2.1 mm, TL/GW = 1.9-2.1, HW/EW = 1.6-1.7, WC/WV = 4.1-4.8. Body shape elongate oval, widest slightly posteriad of middle; lateral margins broadly curved, continuously curved between pronotum and elytron (Fig. 12 ). Depressed and somewhat flattened in lateral aspect. Coloration . Head dark green to green-rufous throughout. Pronotum dark green with broad lateral green-rufous margins. Elytron dark green with broad lateral green-rufous margins. Ventral surfaces dark rufous. Sculpture and structure . Head broad, anteriorly produced, eyes prominent; dorsal surface evenly covered with extremely fine microsculpture and micropunctures. Pronotum with lateral margins evenly and broadly curved; surface similar to surface of head in microsculpture and micropunctation; pronotum somewhat swollen anteriorly. Elytron with margins very broadly curved; surface similar to surface of head in microsculpture, but with extensive, very fine micropunctation. Prosternal process anteriorly rounded, surface flat and broad, apex elongate and sharply pointed. Metaventral wing moderately broad, ~ 1/3 width of lateral portion of metacoxa; surface smooth, without sculpturing. Lateral portion of metacoxa large, broad, surface smooth, without sculpturing; metacoxal lines short, extending anteriorly less than half distance across metacoxa. Abdominal ventrites smooth, unsculptured. Male genitalia . Male median lobe in lateral aspect broad throughout, subapically somewhat expanded, apically narrowed, apex with multiple small processes (Fig. 39 ); in dorsal aspect moderately narrow, evenly narrowed apically, apex narrowly lobed, ventral sclerite apically broadly lobed, extending to near apex (Fig. 40 ). Lateral lobe broad throughout length, evenly curved, apex rounded, with long series of setae along ventral margin (Fig. 41 ). Female genitalia . The single female specimen available for examination lacks female genitalia which apparently have been dissected and lost. Sexual dimorphism . Males have a broad protarsal palette with ventral adhesive setae with apical structures in the form of elongate flattened structures; males also have mesotarsomeres with posteroventral fields of setae. Females lack natatory setae along the ventral margins of the metatarsomeres, but these are present in males. Males and females each have unequal length metatarsal claws with the posterior shorter, but in males the posterior claw is relatively longer than in females, and distinctly, but only somewhat, shorter than the anterior (~ 4/5 of length). Variation . Two paratype specimens were examined, a male and a female. The female has the extent and intensity of greenish-rufous coloration somewhat greater than the male, but otherwise the two specimens are similar. Distribution. This species is known only from Santa Rita, Bahia State, Brazil. I ndication by Tremouilles (1984) of the locality "Santa Rita" to Goyas State, Brazil is erroneous. In Brazil, there are several locations called Santa Rita, but in all labels of the type materials indicate "Santa Rita BA" in clear reference to Bahia State, Brazil (BA = abbreviation of Bahia) and not to Goias State (= GO). "Goyaz" is an old spelling of Goias State. Habitat. Nothing is known of the habitat of this species. Material examined. Twelve specimens in MZSP - holotype male and nine paratypes , six males and three females , each specimen labeled, "Santa Rita BA - Brasil IV.1958 E. Dente col. [label with black line border]/ Cybister (Cybister) parvus E. Tremouilles [handwritten] 1990 det. E. R. Tremouilles [label with black line border]/ Cybister (Meganectes) parvus . 1984 Tremouilles [red label, black line border, handwritten]". Holotype , one paratype female and the other paratypes respectively labeled, " Holotypus [red label, black line border], Holotypus [red label, black line border], Paratypes [label with black line border]"; two paratypes in MLP - one male and one female , each specimen labeled, "Santa Rita BA - Brasil IV.1958 E. Dente col. [label with black line border]/ Cybister (Cybister) parvus E. Tremouilles [handwritten] 1990 det. E. R. Tremouilles [label with black line border]/ PARATYPUS / MUSEO DE LA PLATA PARATIPO Cybister (Meganectes) parvus . 1984 Tremouilles [red label, black line border, handwritten]."