Fontidessus ornatus Miller

Miller, Kelly B. & Spangler, Paul J., 2008, Fontidessus Miller and Spangler, a new genus of Bidessini from Venezuela (Coleoptera: Dytiscidae: Hydroporinae) with three new species, Zootaxa 1827, pp. 45-52 : 50

Fontidessus ornatus Miller , new species

( Figs 2, 6 , 11–13 )

Type locality. Venezuela, Territorio Federal Amazonas, 40km S Puerto Ayacucho, at El Tobogán, Coromoto.

Diagnosis. This species is smaller than F. toboganensis (TL <1.3mm), but is similar in size (though slightly smaller) and external appearance to F. wheeleri . Fontidessus ornatus has the prosternal process moderately elongate with the lateral margins in the apical portion straight and evenly tapered to the pointed apex ( Fig. 6 ). The pale regions on the elytron are diffuse and poorly demarcated and are yellow-brown unlike F. wheeleri which have the elytral maculae brighter yellow and more clearly demarcated. The male genitalia are diagnostic with the median lobe slender and elongate with a subapical brush of setae on the ventral margin ( Fig. 12 ).

Description. Measurements. TL = 1.1–1.2 mm, GW = 0.6–0.7 mm, PW = 0.6–0.7 mm, HW = 0.4–0.5 mm, EW = 0.1–0.2 mm, TL/GW = 1.8–1.9, HW/EW = 1.5–1.6. Body ( Fig. 2 ) oval, elongate; lateral outline slightly continuous between pronotum and elytron; lateral margins of pronotum gently curved; lateral margins of elytron evenly and gently curved.

Coloration. Head yellow brown, darker in region near medial margins of eyes; pronotum yellow brown, diffusely brown medially along posterior margin and in narrow band along anterior margin; elytron brown with diffuse yellow pattern, yellow basally, laterally along about ¾ length of elytra and in subtriangular subapical area ( Fig. 2 ). Ventral surfaces of thorax and abdomen brown except prosternum, prosternal process, propleuron and pronotal epipleuron yellow-brown; appendages yellow to yellow-brown.

Sculpture and structure. Head with very fine, inconspicuous, irregular punctation, surface between punctures shiny with indistinct microsculpture in the form of small cells; eyes medium in size ( Fig. 2 , HW/EW = 1.5–1.6). Pronotal surface similar to that of head; with posterior angles obtuse; lateral bead slender, of even width throughout; pronotal striae finely incised, extending nearly 1/2 distance across pronotum ( Fig. 2 ). Elytron with anterolateral angle obtuse, not extended anteriorly ( Fig. 2 ); surface similar to pronotum but with microsculpture more indistinct. Prosternal process relatively narrow, lateral margins tapered to narrowly rounded apex ( Fig. 6 ); metacoxal process with lateral lobe minute. Pro- and mesotarsi relatively narrow in both male and female.

Male genitalia. Median lobe in ventral aspect slender, elongate and with lateral margins parallel to pointed apex ( Fig. 11 ); in lateral aspect moderately broad at base, curved, with apical portion evenly tapered to pointed apex, subapically with small brush of setae ( Fig. 12 ). Lateral lobe elongate, expanded apically, broadly rounded at apex, with series of long setae along dorsal margin ( Fig 13 ).

Etymology. The species name is derived from the Greek root orno, meaning “adorned,” for the attractive coloration characterizing this species.

Distribution and habitat. The species is known only from the type locality. Label data indicated the following habitats; “seep,” and “bare rock streambed.”

Material examined. HOLOTYPE in USNM: male labeled, “ VENEZUELA: T.F. Amazonas Puerto Ayacucho (40km.S) at Tobogán, 22Feb1986 P.J. Spangler, Colln.#6/ Bare rock streambed in sunlight; beneath wet leaves at margin/ HOLOTYPE: Fontidessus ornatus Miller, 2008 [red label with double black line bor- der].” PARATYPES, 14 total; 3 with same label data as holotype; 9, Venezuela, T.F. Amazonas, Puerto Ayacucho, 40km S El Tobogán, Caño Coromoto, 23 January 1989, seep at upper shelter, P.J. Spangler, R.A. Faitoute, and C.B. Barr; 2, same except 26 January 1989.

Figures

FIGURES 1 – 7. Fontidessus species. 1 – 3) Dorsal habitus, 1) F. toboganensis, 2) F. ornatus, 3) F. wheeleri. 4) F. toboganensis, left metatrochanter and metafemur, anterior aspect. 5 – 7) prosternal process, 5) F. toboganensis, 6) F. ornatus, 7) F. wheeleri. Scale bar a = 1.0 mm for Figs 1 – 4. Scale bar b = 0.1 mm for Figs 5 – 7.

FIGURES 8 – 17. Fontidessus species. 8 – 10) F. toboganensis, male genitalia, 8) median lobe, dorsal aspect, 9) median lobe, right lateral aspect, 10) right lateral lobe, right lateral aspect. 11 – 13) F. ornatus, male genitalia, 11) median lobe and left lateral lobe, dorsal aspect, 12) median lobe, right lateral aspect, 13) right lateral lobe, right lateral aspect. 14 – 16) F. wheeleri, male genitalia, 14) median lobe and left lateral lobe, dorsal aspect, 15) median lobe, left lateral aspect, 16) right lateral lobe, right lateral aspect. 17) F. toboganensis, female genitalia, ventral aspect. Scale bars = 0.1 mm.