Fontidessus ornatus Miller, 2008

Miller, Kelly B. & Montano, Elizabeth T., 2014, Review of the genus Fontidessus Miller & Spangler, 2008 (Coleoptera, Dytiscidae, Hydroporinae, Bidessini) with description of four new species, ZooKeys 426, pp. 65-85 : 75-77

Taxon classification Animalia Coleoptera Dytiscidae

Fontidessus ornatus Miller, 2008 Figs 7, 8, 15, 22, 29, 33

Fontidessus ornatus Miller, 2008: 50 in Miller and Spangler 2008.

Type locality.

Venezuela, Territorio Federal Amazonas, 40km S Puerto Ayacucho, at El Tobogan, Coromoto.

Diagnosis.

Fontidessus ornatus are very small (Figs 7, 8, TL = 1.09-1.20). Specimens are diffusely marked with yellow on the elytron anteriorly, medially and laterally (Fig. 8) or are nearly entirely darkly colored (Fig. 7). The median lobe terminates apically in two slender rami with two very broad, lateral hyaline lobes (Fig. 29).

Redescription.

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 (Figs 7, 8) 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. 8). Other specimens much darker, with elytral maculae reduced overall (Fig. 7). 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 (Figs 7, 8, 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 (Figs 7, 8). Elytron with anterolateral angle obtuse, not extended anteriorly (Figs 7, 8); surface similar to pronotum but with microsculpture more indistinct. Prosternal process relatively narrow, lateral margins tapered to narrowly rounded apex (Fig. 15); metacoxal process with lateral lobe minute. Pro- and mesotarsi relatively narrow in both male and female. Metatrochanter very large relative to metafemur (Fig. 22).

Male genitalia. Median lobe in dorsal aspect complex, apically terminating in two elongate, narrow rami with medial deep, narrow emargination, laterally with broad, hyaline lobes (Fig. 29A); in lateral aspect narrow, straight, apically with distinct subapical hyaline lobe and apex slightly bent, apically very slender (Fig. 29C); ventral sclerite short, broad, apically rounded (Fig. 29B). Lateral lobe slender medially, apically expanded and broadly rounded (Fig. 29D).

Variation.

This species exhibits considerable variation in color between the two main regions in which it has been collected (Surinam/Guyana and Venezuela). The eastern specimens are noticeably darker in overall coloration (Fig. 7) than those from Venezuela which are more distinctly marked with yellow maculae on the elytra and lighter in color on the pronotum and head (Fig. 8). The distinctive male genitalia (Fig. 29) are similar in each of the two populations, though, and so this color variation is regarded as intraspecific.

Distribution and habitat.

Fontidessus ornatus is more widespread and common than other species in the genus. It ranges from the western margin of the Guiana Shield through northeastern Venezuela to central and southern Suriname (Fig. 33). It is found in hygropetric habitats.

Comments.

The original description of Fontidessus ornatus included 15 specimens. This type series was mixed together with specimens of Fontidessus toboganensis and Fontidessus wheeleri . The holotype of Fontidessus ornatus had already been dissected, but based on considerable new material, it appears that the genitalia had been damaged somewhat and, worse yet, exchanged with the genitalia of what became the holotype of Fontidessus wheeleri . The genitalia are redescribed and reillustrated here based on newly dissected specimens with greater precision and in correct association with the species to which they belong.

Material examined.

~400 total from the following localities: VENEZUELA: Amazonas: 40km S Puerto Ayacucho, El Tobogan, Caño Coromoto 5.38678°N, 67.61537°W; Bolivar: Los Pijiguaos at rock outcrop, 6.59361°N, 66.82063°W; rock outcrop by Rio Cuchivero 7.45835°N, 65.86821°W; outcrop ca 15km NE Pijiguaos, 6.96506°N, 66.60653°W; rock outcrop by morichal, 6.86993°N, 66.59083°W; 2km E Rio Chucivero, 7.45835°N, 65.86821°W; ca 25km E El Burro, 6.21794°N, 67.24066°W; along La Escalera, Hwy 10, 6.08186°N, 61.39797°W; ca 14km E Rio Aro, 7.23988°N, 64.0322°W. SURINAME: Sipaliwini District: camp 2, Sipaliwini Riv., 2.18288°N, 56.78725°W; Raleighfallen Nature Reserve plateau below Voltzberg, 4.68276°N, 56.1877°W; Sipaliwini District: Tafelberg Summit, nr Augustus Creek Camp, large seepage area, 3°55.600'N, 56°11.300'W 600m. GUYANA: Region IX, Kusad Mtns, large seepage nr. Basecamp; on wet rocks, and Mokoro Creek main seepage area, 2°48.531'N, 59°51.900'W, 170m.