Rhantus lattkei Balke, Garcia, Hendrich, 2019

Balke, M., Garcia, M. & Hendrich, L., 2019, Two new species of diving beetles from the Duida-Marahuaca Tepui in Venezuela (Coleoptera: Dytiscidae: Colymbetinae), Russian Entomological Journal 28 (3), pp. 258-262 : 259-260

Rhantus lattkei Balke, Garcia, Hendrich , sp.n.

Figs 1 , 6–12, 14 .

LIFE SCIENCE IDENTIFIER. Registered in Zoobank (www.zoobank.org) as urn:lsid:zoobank.org:act:4215889D-2A8F-4D5E-B7AD-89C3D1773C3C .

TYPE LOCALITY. Venezuela: Amazonas state: Duida-Marahuaca National Park: highland below the Cerro Marahuaca (Marahuaca Tepui, Marawaca) .

MATERIAL. Holotype, ♂ ( MIZA):“ Venezuela: Amazonas state, PN [Parque Nacional] Duida-Marahuaca, Macizo Central [central range], 3°40 ' N, 65°28 ' W, 1040 m, 8.iii.1985, J. Lattke ”. Paratype: 1♀, same label data ( ZSM). The specimens bear our red type labels .

DESCRIPTION. A smaller Rhantus species, total length of holotype 6.5 mm, greatest width 3.3 mm (paratype 6.2/3.1 mm). The beetles are rather parallel-sided in dorsal view ( Fig. 1 ); the posterior margin of the pronotum is distinctly concave, the pronotum is thus shorter medially than laterally, and of overall double as head shape.

Colour. Head orange, darker behind the eyes. Pronotum orange, base and anterior margin as well discal area somewhat darkened. Elytron orange with black irrorations. Body appendages, prothorax, prosternal process, epipleuron, coxae, postcoxal process and hind margins of abdominal sternites orange to dark ferrugineous.

Surface sculpture. Head with irregular polygonal meshes and double punctation, densest on frons, no microreticulation (MR) visible; clypeus with double punctation only. Pronotum with double punctation and more-or-less defined polygonal meshes; no MR visible on pronotum. Elytron with distinct, irregular polygonal meshes and fine punctation; devoid of MR within the meshes. Last ventrite with transversally oriented MR and small punctures, without lateral rugae.

Structures. Pronotum with broad and conspicuous lateral bead which distinctly reaches the anterior angle. Prosternal process very short and broadly rounded on ventral side, hardly reaching anterior level of meseocoxae (in other species usually exceeding this level distinctly) ( Fig. 12 ). Lateral wings of metaventrite very narrow ( Fig. 14 ); hind wings vestigial. Last ventrite rounded apically.

Tarsal characters. Protarsal and mesotarsal claws sinuate, shorter than fifth protarsomere ( Figs 10–11 ). Pro- and mesotarsomeres 1–3 only hardly expanded laterally, with four transverse rows of stalked suction discs ventrally. Number of discs per row (tarsomere on which row occurs given in parentheses): 3(1)/4(1)/4(2)/3(3).

Genital structure. Median lobe of aedeagus as in Figs 6– 7 , parameres with only few rather short yellow hairs which are apically acute, not trumpet shaped ( Fig. 8 ).

Female. Gonocoxa as in many other species of the genus, elongate-oval, with numerous short and few stout setae on the tip and along the interior margin ( Fig. 9 ).

ETYMOLOGY.Named for the species’ collector, John Lattke. The specific epithet is a substantive in the genitive case.

COMPARATIVE NOTES. A species well-characterized by the following set of features: small size, pronotum double axhead shaped ( Fig. 1 ); prosternal process short, broadly rounded ventrally and almost diamond shaped ( Fig. 12 ); parameres with few short setae only ( Fig. 8 ); lateral wings of metaventrite rather narrow ( Fig. 14 ); hind wings vestigial.

DISTRIBUTION. Rhantus lattkei sp.n. is only known from the type locality.

HABITAT. Most likely small puddles.

Figures

Figs 1–5. Habitus of Rhantus spp.: 1 — R. lattkei sp.n.; 2 — R. marahuaca sp.n.; 3 — R. elegans; 4 — R. andinus (Colombia, Bogota, La Florida); 5 — R. andinus (Venezuela, Merida, Azulita). Рис. 1–5. Rhantus spp., внешний вид: 1 — R. lattkei sp.n.; 2 — R. marahuaca sp.n.; 3 — R. elegans; 4 — R. andinus (Colombia, Bogota, La Florida); 5 — R. andinus (Venezuela, Merida, Azulita).

Figs 6–15. Rhantus spp.: 6–12, 14 — R. lattkei sp.n.; 13 — R. elegans; 15 — R. marahuaca sp.n.; 6–7 — median lobe; 8 — paramere; 9 — gonocoxa; 10 — foretarsus, 11 — middletarsus; 12 — prosternal process and part of metasternum; 13–15 — lateral “wing” of metaventrite; 6, 8–9, 12–15 — ventral; 7 — lateral;10–11 — anterior. Scale bar: 0.5 mm for 9–11; 1.0 mm for 6–8, 12–15. Рис. 6–15. Rhantus spp.: 6–12, 14 — R. lattkei sp.n.; 13 — R. elegans; 15 — R. marahuaca sp.n.; 6–7 — Эдеагус; 8 — парамера; 9 — гонокоса; 10 — переднЯЯ лапка, 11 — среднаЯ лапка; 12 — отросток переднегруди и часть Заднегруди; 13–15 — боковые “крыльЯ” метавентрита; 6, 8–9, 12–15 — сниЗу; 7 — сбоку;10–11 — спереди. Масштаб: 0,5 мм длЯ 9–11; 1,0 мм длЯ 6–8, 12–15.