Rhantus marahuaca Balke, Garcia et 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 : 260-262

Rhantus marahuaca Balke, Garcia et Hendrich , sp.n.

Figs 2 , 15 , 19–21, 23.

LIFE SCIENCE IDENTIFIER. Registered in Zoobank (www. zoobank.org) as urn:lsid:zoobank.org:act:39EF91FE-AA3F-48C5-88BC-CCC02FFBD0BF .

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

MATERIAL. Holotype, ♂ ( MIZA) : Venezuela: Amazonas state: “Marahuaca , 2750 m.a.s.l., 6.–16.x.1983, Exp. Marawaca Fund.[ación] Terramar” ( MIZA) . Paratype: 1 ♀, “PN [Parque Nacional] Duida-Marahuaca, Cerro Marahuaca , 2470 m.a.s.l. (3°37 ' N / 65°22 ' W), 3.–6.ii.1992, J. Clavijo & A. Chacón, Exp. Marawaca Fund.[ación] Terramar” ( ZSM) . The specimens bear our red type labels.

DESCRIPTION. A medium sized Rhantus . Total length of holotype 9.2 mm, greatest width 4.8 mm (paratype 9.0/4.6

mm). The beetles are elongate oval in dorsal view ( Fig. 2 ); the posterior margin of the pronotum is slightly convex.

Colour (The specimens appear rather darkened, Fig. 2 ). Head blackish, clypeus dark orange. Pronotum blackish, laterally dark orange. Elytron dark orange with numerous black irrorations and overall dark appearance. Body appendages, prothorax, prosternal process, epipleuron, coxae, and postcoxal process to dark ferrugineous; rest of venter blackish. Fresh specimens are presumably lighter, comparable to a freshly hatched specimen of R. elegans figured here ( Fig. 3 ).

Surface sculpture. Head with irregular, deeply impressed polygonal meshes and double punctation; with fine MR visible; clypeus with double punctation only. Pronotum and elytron with fine, in part double punctation and more or less defined, well impressed polygonal meshes; faint microreticulation (MR) visible. MR distinct laterally and apically on elytron. Last ventrite with transversally oriented MR and punctures, with distinct longtitidinal rugae laterally (different in female, see below).

Structures. Pronotum with broad and conspicuous lateral bead which does not reach the anterior angle. Prosternal process long, narrow, with ventral ridge, reaching almost the hind margin of mesocoxae; fitting into v-shaped counterpart of mesoventrite. Lateral wings of metaventrite narrow ( Fig. 15 ). Flight wings apparently fully developed (the elytra were not removed, but are slightly spread in the female, allowing tentative inspection of flight wings).

Tarsal characters. Protarsal and mesotarsal claws sinuate, shorter than fifth protarsomere (similar to the shape shown in Figs 10–11 for R. lattkei sp.n.). Pro- and mesotarsomeres 1–3 only hardly expanded laterally, with four rows of stalked suction discs ventrally. Number of discs per transverse row (tarsomere on which row occurs given in parentheses): 4(1)/5(1)/5(2)/4(3) (needs confirmation as specimen in poor shape).

Genital structure. Median lobe of aedeagus as in Figs 19–20, surface of basal part rugose; parameres with dense and long setation, setae apically acute, not trumpet shaped (Fig. 21, dotted line = limit of setation). Last ventrite apically slightly truncate; laterally rather rugose (Fig. 23), medially slightly so, with dense punctation but no obvious meshes; base with MR.

Female. Elytral meshes slightly more deeply impressed than in male, giving a duller impression. 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. Last ventrite apically rounded; laterally with distinct rugae but less so than in male, medially smooth, with dense punctation but no obvious meshes; base with MR.

ETYMOLOGY. Named for the type locality, Cerro Marahuaca.

19 20 21

Figs 16–23. Rhantus spp. : 16–18, 22 — R. elegans ; 19–21, 23 — R. marahuaca sp.n.; 16–17, 19—20 — median lobe; 18, 21 — paramere; 22–23 — last ventrite; 16, 18–19, 21, 22–23 — ventral; 17, 20 — lateral.

Рис. 16–23. Rhantus spp. : 16–18, 22 — R. elegans ; 19–21, 23 — R. marahuaca sp.n.; 16–17, 19—20 — Эдеагус; 18, 21 — парамера; 22–23 — последний вентрит; 16, 18–19, 21, 22–23 — сниЗу; 17, 20 — сбоку.

COMPARATIVE NOTES. A smaller Rhantus , male with simply curved claws and predominantly dark pronotum. Similar to R. elegans Waterhouse, 1895 from Roraima Tepui (~ 550 km east of Marahuaca). Rhantus marahuaca sp.n. differs from R. elegans as follows: Male genitalia (Figs 19–21; R. elegans : 16–18), last ventrite: apically rounded and slightly rugose in R. elegans (Fig. 22), apically truncate and rather rugose laterally in R. marahuaca sp. n. (Fig. 23). Certainly, more specimens need to be examined to evaluate the latter character. The shape of the lateral wings of metaventrite does not differentiate R. elegans ( Fig. 13 ) and R. marahuaca sp.n. ( Fig. 15 ).

DISTRIBUTION. R. marahuaca 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.