Fontidessus toboganensis Miller and Spangler

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 : 48-49

Fontidessus toboganensis Miller and Spangler , new species

( Figs 1, 4, 5 , 8–10, 17 )

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

Diagnosis. This is the largest known species in the genus (TL> 1.4mm). The prosternal process is moderately broad and parallel-sided and has the apex broadly truncate ( Fig. 5 ). The male genitalia are distinctive with the median lobe elongate, slender and broadly recurved in lateral aspect ( Fig. 9 ). There is an elongate ventral sclerite that fits into the ventral groove of the median lobe ( Fig. 9 ).

Description. Measurements. TL = 1.5–1.6 mm, GW = 0.8–0.9 mm, PW = 0.6–0.7 mm, HW = 0.4–0.5 mm, EW = 0.3–0.4 mm, TL/GW = 1.8–1.7, HW/EW = 1.6–1.7. Body ( Fig. 1 ) oval, elongate; lateral outline nearly continuous between pronotum and elytron; lateral margins of pronotum gently curved; lateral margins of elytron evenly and gently curved.

Coloration. Head yellow brown, pronotum yellow brown, brown medially along posterior margin ( Fig. 1 ); elytron brown with the following yellow maculae: 1) a basal macula in a band extending from lateral to sutural margins, posterior margin of macula irregular, 2) a lateral longitudinal macula at humeral angle, 3) a narrow longitudinal macula along lateral margin, and 4) a subtriangular subapical macula ( Fig. 1 ). 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. 1 , HW/EW = 1.6–1.7). Pronotal surface similar to that of head; with posterior angles obtuse; lateral bead narrow, of even width throughout; pronotal striae finely incised, extending nearly 1/2 distance across pronotum ( Fig. 1 ). Elytron with anterolateral angle obtuse, not extended anteriorly ( Fig. 1 ); surface similar to pronotum. Prosternal process broad, lateral margins subparallel, apex of process broadly rounded ( Fig. 5 ); metacoxal process with lateral lobe minute. Pro- and mesotarsi relatively narrow in both male and female, but slightly broader in male.

Male genitalia. Median lobe in ventral aspect extremely slender and long, apex slender and sharply pointed ( Fig. 8 ); in lateral aspect narrow, extremely slender and long in apical half, abruptly curved medially to sharply pointed, recurved apex ( Fig. 9 ); with elongate, slender dorsal sclerite ( Fig. 9 ). Lateral lobe in lateral aspect broad basally, bent medially with apical segment elongate and parallel sided to narrowly rounded apex ( Fig 10 ).

Female genitalia ( Fig. 17 ). Bursa copulatrix elongate and narrow; spermathecal duct long, slender, somewhat coiled, expanded prior to receptacle; receptacle small, about half size of spermatheca, intermediate duct between receptacle and spermatheca broad; spermatheca globular, spermathecal spine prominent, but not elongate; fertilization duct elongate, tightly curved in spiral, attaching to large fertilization sac; vagina elongate, moderately narrow; gonocoxae elongate, slender with abrupt, small, triangular expansion at apex ( Fig. 17 ).

Etymology. The species name is derived from the name of the type locality, El Tobogán.

Distribution and habitat. According to notes discovered in P.J. Spangler’s office: “The series of [ Fontidessus toboganensis ] was collected from seepage areas alongside a cascade. The specimens were obtained by pulling matted plant roots from granitic bedrock and using an aspirator to suck up the water that accumulated in rock depressions as runoff from the roots. The dirty concentrated residue was then filtered through fine-meshed, nylon cloth and the very small adults and larvae were again aspirated as they crawled out of the residue.”

Label data indicate the collection of specimens of the species from the following habitats: “seep,” “sunlit stream”, “bare rock streambed in sunlight; beneath wet leaves at margin,” “sunlit stream; slow water over sand and gravel,” and “leaves from stream.”

Material examined. HOLOTYPE in USNM: male labeled, “ VENEZUELA: T.F. Amazonas Puerto Ayacucho (40km.S) El Tobogán, Cano Coromoto 26 January 1989 / seep at upper shelter collected by PJSPangler RAFaitoute&CBBarr/ HOLOTYPE: Fontidessus toboganensis Miller and Spangler, 2008 [red label with double black line border].” PARATYPES, 250 total, all with same locality data as holotype, 11 with same collecting date as holotype; 1 with 22 February 1986; 21 with 25 February 1986; 24 with 21 January 1985; 1 with 16 November 1987; 192 with 23 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.