Agaporomorphus colberti, Miller & Wheeler, 2008

Miller, Kelly B. & Wheeler, Quentin D., 2008, A new species of Agaporomorphus Zimmermann from Venezuela, and a review of the A. knischi species group (Coleoptera: Dytiscidae: Copelatinae), Zootaxa 1859 (1), pp. 63-68 : 64-67

Agaporomorphus colberti sp. n.

( Figs 1, 6 , 7–9, 21)

Type locality. Venezuela, Departamento Amazonas, Rio Negro, Rio Baria , Dpt Rio Negro , 00°55’N 066°10’W .

Diagnosis. Agaporomorphus species are extremely similar in characters such as size, general shape and coloration ( Fig. 1 ). This species can be distinguished from all other known Agaporomorphus except A. knischi by the following character combination in males: 1) antennomeres V and VI broadly expanded with VI more expanded than V and with a distinct emargination on the posteroventral surface ( Fig. 4 ), 2) abdominal sternite V with an apicomedial triangular process ( Figs 5, 6 ), and 3) abdominal sternite VI with a broad medial fovea ( Figs 5, 6 ). This new species can be clearly placed within a group of species (the A. knischi species group) characterized by distinctly modified male genitalia with a short series of fine setae on each side of the ventral surface (Figs 7, 10, 13, 17). Within this group, A. colberti sp. n. is most similar to A. knischi in having the character combination indicated above, but differs from that species in the shape of the male median lobe of the aedeagus (Figs 7, 8) which is broader in ventral and lateral aspects and has a prominently broad and dorsally angulate ventral region near the base that is narrower in A. knischi (Figs 17, 18), among numerous other shape features. Also, the posteromedial spine on abdominal sternite V is smaller in A. colberti sp. n. ( Fig. 5 ) than in A. knischi ( Fig. 6 ).

Description. Measurements. TL = 2.93–3.18mm, GW = 1.39–1.57mm, PW = 1.24–1.38mm, HW = 0.78– 0.87mm, EW = 0.49–0.58mm, TL/GW = 1.97–2.18, HW/EW = 1.50–1.64, FW/FL = 2.59–3.22.

Coloration ( Fig. 1 ). Red-brown on all dorsal surfaces, broadly light yellow along anterior margin of elytron and lateral margins of pronotum. All ventral surfaces and appendages yellow-brown except abdominal sternites red-yellow.

Sculpture and structure. Pronotum with microsculpture consisting of fine cells, with few very fine punctures interspersed; lateral pronotal bead fine, absent in anterior one-fifth. Prosternum medially strongly carinate, carina extending onto prosternal process; prosternal process medially with a distinct, sharp longitudinal carina extending to apex, laterally with strongly beaded margins, apex pointed. Elytron covered with extremely fine, evenly spaced, short striae, striae more punctiform laterally and apically. Metafemur moderately broad, length about 3 × greatest width.

Male genitalia; Median lobe in lateral aspect robust, with broad expansion dorsad, apex elongate, sublinear, with distinct dorsally-directed lobe on right side medially and very broad, angular region subbasally, with linear series of fine setae on each side of dorsal midline (Fig. 7); in ventral aspect very robust, broad, with complicated folding and structures (Fig. 8). Lateral lobe broad basally, strongly narrowed medially, apical half very slender, apicomedially with large membranous lobes bearing extensive series of long setae (Figs 9).

Female genitalia; Spermatheca long, loosely coiled, slender, tapered to spermathecal duct; spermathecal duct relatively short; fertilization duct long, coiled; gonocoxa slender, lateral margin broadly convex, apex expanded; laterotergite very slender, elongate.

Sexual dimorphism. Male protarsal claws unmodified; male pro- and mesotarsal claws about half length of mesotarsomere V; male without apical lobe on mesotarsomere V; male protarsomeres I and II broadened, protarsomere I with two large adhesive setae, protarsomere II without adhesive setae; male mesotarsomeres I and II slightly broadened, mesotarsomere I with one large, medial adhesive seta and two large, apical adhesive setae, mesotarsomere II with two smaller, apical adhesive setae; female pro- and mesotarsomeres unmodified. Male with fine but distinct triangular, posteriorly-directed prominence medially along posterior margin of visible abdominal sternite V ( Fig. 5 ); female without prominence. Male with broad, elongate depression medially on abdominal sternite VI ( Fig. 5 ); female without depression. Male with distinct parallel series of rugulosities on each side of midline on abdominal sternite III ( Fig. 5 ); female without rugulosities. Male antennomeres V and VI modified, V broadly triangular, VI broad with large posterior emargination (as in Fig. 4 ); female antennomeres unmodified. Male metafemur unmodified.

FIGURES 7–20. Agaporomorphus species , male gentitalia. 7–9) A. colberti ; 10–12) A. silvaticus ; 13–16) A. tambopatensis ; 17–20) A. knischi . 7, 10, 13, 17) median lobe, right lateral aspect; 8, 11, 14, 18) median lobe, ventral aspect; 9, 12, 15, 19) right lateral lobe, right lateral aspect. 16, 20) left lateral lobe, right lateral aspect.

Etymology. This species is named to honor comedian and author, Stephen T. Colbert.

Phylogenetic relationships. The phylogenetic analysis resulted in a single parsimony tree ( Fig. 21 , length=13, CI=92, RI=94). This topology is identical to the one found by Miller (2005) with the addition of A. colberti sp. n. as the unambiguous sister to A. knischi ( Fig. 21 ) based on the synapomorphy of modified antennomere V in addition to VI (e.g. Fig. 4 , A. tambopatensis also has antennomere VI modified, though to a lesser extent, Fig. 3 ). Although not otherwise coded in this analysis because of challenges in homologizing complex shape features, A. colberti sp. n. and A. knischi exhibit considerable general similarity in the shape of the male median lobes (Figs 7, 8, 15, 18).

Distribution. Agaporomorphus colberti sp. n. is currently known only from the type locality in extreme southern Venezuela near the border with Brazil. This is the only Agaporomorphus known from Venezuela.

Material examined. HOLOTYPE: ♂ in MIZA labeled, “ Venezuela T-F Amazonas Dpt Rio Negro / Rio Baria 140m. 0°55’N 66°10’W / L.J.Joly A.Chacon 4-11- II-8 [date handwritten]/ HOLOTYPE: Agaporomorphus colberti Miller and Wheeler, 2008 [red label with black line border].” PARATYPES, 10 total, in MIZA, USNM and MSBA labeled same as holotype except “…/ PARATYPE: Agaporomorphus coberti Miller and Wheeler, 2008 [blue label with black line border].”

Figures

FIGURE 21. Single most parsimonious cladogram of Agaporomorphus species (length = 13, CI = 92, RI = 94). Numbers above hatch marks refer to characters numbers. Numbers below hatch marks refer to derived character state transformations.

FIGURES 1–6. Agaporomorphus species, morphological details. 1, 5) A. colberti; 2) A. silvaticus; 3) A. tambopatensis; 4, 6) A. knischi. 1) dorsal habitus; 2–4) male left antenna, ventral aspect; 5, 6) visible abdominal sternites, ventral aspect. Scale bars; a = 1mm for Figs 1,5,6; b = 0.25mm for Figs 2–4.