Tegyrius bicolor Prathapan & Viraktamath, 2009

Prathapan, K. D. & Viraktamath, C. A., 2009, Revision of Tegyrius (Coleoptera: Chrysomelidae: Galerucinae: Alticini), with descriptions of eight new species, Zoological Journal of the Linnean Society 157 (2), pp. 326-358 : 335-337

TEGYRIUS BICOLOR ( MEDVEDEV, 2001) COMB. NOV. ( FIGS 25–31 )

Lankaphthona bicolor Medvedev, 2001: 163 , 164. Holotype (LMC) examined.

Distribution: Sri Lanka .

Host plant: Collected on Piper sp.

Description: Head and pronotum piceous; basal area of pronotum and mouth parts with dark-brown tinge. Elytra, meso- and metathoracic, and abdominal sternites red–brown. Suture slightly darker than the rest of the elytra. Antennae and all legs yellow, except for metafemora, which are red–brown.

Supraorbital sulcus distinct. The relative lengths of antennomeres vary significantly: third antennomere subequal to fourth and fifth; sixth shorter than fifth; seventh longer than sixth; eighth and ninth subequal, each shorter than seventh; tenth shorter than ninth; last longer than first; distal fourth and fifth antennomeres slightly thickened; antennae extend beyond the middle of the elytra over the pronotum.

Pronotum without antebasal transverse impression. Apex of prosternal intercoxal process convex, with two preapical depressions. Prosternal intercoxal process 2.4 times wider than the distance between the anterior margin of the prosternum and the coxal cavity; distance from the anterior margin of the prosternum to the end of the intercoxal prosternal process 2.3 times the minimum width of the prosternal intercoxal process.

Mesoscutellum as long as broad, with narrowly rounded apex. Mesosternum depressed in the middle, with raised anterior and posterior margins; posterior margin concave. Elytra with maximum width at anterior third; elytral apex distinctly convex, moderately broad; elytral punctures minute to moderately strong, confused, and tend to form rows, with the distance between adjacent punctures 0.1–1.8 times the diameter of a puncture in the anterior half of the elytron.

Subparallel ridges on first abdominal ventrite extend beyond three-quarters of its length, and converge distally ( Fig. 25 ). Last visible tergite of females with a longitudinal groove along the middle. Last visible ventrite of males with the middle lobe infolded, and distally widening, with concave apical margin; with a denticle proximal to the middle lobe ( Fig. 26 ), middle lobe infolded, widening anteriorly, distal margin concave ( Fig. 27 ).

Aedeagus moderately curved with apical knob, proximal end crooked in lateral view ( Fig. 29 ); in ventral view, slightly widened at the middle, ventral surface with a deep furrow, and apex deeply emerginate ( Fig. 28 ); distal opening partially covered with lamina ( Fig. 30 ); arm of tegmen subequal to stem ( Fig. 31 ).

Female unknown.

Sexual dimorphism: First protarsomere is slightly wider, and the first metatarsomere has a patch of apically flat setae ventromesally. These are probably secondary male sexual characters, as found in the other Sri Lankan species.

Measurements (n = 4): Length, 1.87–2.04 (1.94); width, 1.00–1.08 (1.04); length of pronotum, 0.51–0.58 (0.54); width of pronotum, 0.65–0.71 (0.67); width of head across eyes, 0.49–0.54 (0.52); transverse diameter of one eye, 0.18–0.24 (0.20); distance between eyes, 0.20–0.22 (0.21); distance between eye and antennal socket, 0.02 (0.02); distance between antennal sockets, 0.06 (0.06), diameter of one antennal socket, 0.06–0.07 (0.06); length of aedeagus, 0.72.

Type material examined: Holotype ♂. Labels: (1) Sri Lanka , Beluhil Oya, coll. V. Zaitzev 24 October 1982; (2) Holotypus Lankaphthona bicolor m. L. Medvedev det. 1998; (3) Tegyrius bicolor (Medvedev) K. D. Prathapan det. 2007 (LMC).

Other material examined: 4♂, Sri Lanka , Knuckles Range, Atanwala 7–8, March 2006, coll. K. D. Prathapan (1 BMNH, 1 NHMB, 1 PKDC, and 1 USNM) .

Remarks: Tegyrius bicolor comb. nov. externally resembles T. antennatus comb. nov. Both of them are sympatric, and were collected together. The host plant may also be the same. They can be differentiated from each other by the following characters. Tegyrius bicolor comb. nov. is a little smaller than T. antennatus comb. nov. Antennae and legs, except metafemora, are yellow in T. bicolor comb. nov. (in T. antennatus comb. nov., antennae and legs are black, with red– brown to piceous portions). Antennomeres are thicker in T. antennatus comb. nov. than in T. bicolor comb. nov. The apex of the elytra is strongly convex in T. bicolor comb. nov. compared with T. antennatus comb. nov. Subparallel ridges on first abdominal ventrite distally diverge in T. antennatus comb. nov. (subparallel ridges distally converge in T. bicolor comb. nov.). The shape of the aedeagus can be used to readily differentiate these two species. In T. antennatus comb. nov., the apex of the aedeagus is smoothly rounded in ventral view (deeply emarginated in T. bicolor comb. nov.), the middle region is slightly narrowed (slightly widened in T. bicolor comb. nov.), and the ventral surface has a pair of ridges enclosing a transparent window (ventral side is transparent and deeply furrowed in T. bicolor comb. nov.). The stem of the tegmen of T. antennatus comb. nov. is shorter than the arm (stem is as long as arm in T. bicolor comb. nov.).

Figures

Figures 25–31. Tegyrius bicolor comb. nov. (specimen from Knuckles Range): 25, intercoxal ridges on first abdominal ventrite; 26, male last abdominal ventrite, ventral view; 27, male last abdominal ventrite, posterior view, showing the infolded middle lobe; 28, aedeagus, ventral view; 29, aedeagus, lateral view; 30, distal opening; 31, tegmen.