Tegyrius, JACOBY, 1887

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 : 327-329

publication ID	https://doi.org/ 10.1111/j.1096-3642.2008.00510.x
persistent identifier	https://treatment.plazi.org/id/03E7375E-FFD0-FF92-FF60-9BAA3F189922
treatment provided by	Felipe
scientific name	Tegyrius
status

Treatment

GENUS TEGYRIUS JACOBY, 1887

( FIGS 1–116 View Figures 1–5 View Figures 6–14 View Figures 15–21 View Figures 22–24 View Figures 25–31 View Figures 32–40 View Figures 41–46 View Figures 47–49 View Figure 50 View Figures 51–60 View Figures 61–64 View Figures 65–68 View Figures 69–75 View Figures 76–78 View Figures 79–89 View Figures 90–98 View Figures 99–104 View Figures 105–107 View Figures 108–113 View Figures 114–116 )

Tegyrius Jacoby, 1887: 97 (type species T. metallicus Jacoby, 1887 , Sri Lanka , by monotypy); Maulik, 1926: 285, 409; Chen, 1936: 642; Heikertinger & Csiki in Junk, 1940: 269; Scherer, 1969: 11, 20, 108; Seeno & Wilcox, 1982: 136.

Distribution: India and Sri Lanka .

Host plants: Piper L. and Lepianthes Rafinesque (Piperaceae) .

Description: Moderately small, length 1.5–2.6 mm, width 0.9–1.5 mm ( Fig. 50 View Figure 50 ). Colour light brown to red to black. Head ( Fig. 51 View Figures 51–60 ) hypognathous. In lateral view, frons and vertex convex, with frons distinctly more convex than vertex. Vertex slightly convex, minutely punctate. Supraorbital pore circular, not surrounded by shallow groove, with adjacent minute setiferous pores. Antennal callus well developed, transverse, 2.5–3.0 times wider than long; anteromesal ends angulate, curved, and entering into interantennal space (as in Trachytetra Sharp, 1886 ). Antennal callus as high as vertex near post callinal sulcus, lower near antennal socket than near post-callinal sulcus. All sulci delimiting antennal callus (except supraorbital, which is variable) well developed. Post callinal sulcus slightly oblique, gently curved, deep, as strong as orbital sulcus, stronger than supraantennal and/or suprafrontal sulci. Midfrontal sulcus wider, shorter, and deeper than suprafrontal sulcus. Subgenal suture well developed along base of mandible. Midcranial suture absent. Orbit very narrow, less than half the diameter of the antennal socket. Eye anterolaterad, inner margin weakly concave near antennal socket, vertical diameter 1.1–1.4 times transverse diameter. Distance between eyes 3.0–3.8 times the diameter of a socket, and 1.0–1.2 times the transverse diameter of an eye. Diameter of antennal socket 1.8–3.5 times the distance between the eye and the adjacent socket. Distance between antennal sockets 0.86–1.33 times the diameter of the socket.

Frontal ridge short, acutely narrowed, raised between antennal sockets, and widening anteriorly. Anterofrontal ridge triangular, anteriorly flat above clypeus, not distinct from frontal ridge, with frontal ridge forming indistinct denticle in the middle of the anterofrontal ridge. Frontal ridge together with anterofrontal ridge forming equilateral triangle. Frontoclypeal suture with row of setae. Antennae filiform, and reaching the middle of the elytra or slightly beyond. First antennomere slightly shorter than twice the length of the second antennomere; third antennomere thinner, longer than second, and more or less shorter than fourth antennomere (distinctly shorter than fourth in Tegyrius nigrotibialis sp. nov.). Labrum with four setiferous pores arranged in transverse row, with sensillum on either side of middle pair ( Fig. 61 View Figures 61–64 ). In T. metallicus , mandible with four large denticle besides a tiny denticles on the mesal side ( Fig. 63 View Figures 61–64 ); maxilla with lacinia wider than galea, and sensory patch on last palpomere nearly as long as broad, with about seven embedded sensillae ( Fig. 62 View Figures 61–64 ); labium with penultimate palpomere longer and wider than apical palpomere ( Fig. 64 View Figures 61–64 ).

Pronotum: 1.3–1.5 times wider than long; with or without simple, distinct antebasal transverse impression, never delimited laterally; anteriorly wider; lateral margin curved, widest near middle, posteriorly narrower. Anterolateral callosity concave (variable in Tegyrius dalei sp. nov.). Anterolateral callosity as long as one third of the lateral margin, including the anterolateral callosity (shorter in Tegyrius pucetibialis sp. nov.), with pore situated at posterodorsal face, and forms denticle at pore; anterolateral callosity anteriorly higher than posteriorly. Posterolateral callosity slightly protruding, with pore situated laterally. Posterior margin weakly but distinctly bisinuate. Pronotal punctures small yet stronger than those on vertex. Anterior coxal cavities open. Intercoxal prosternal process extending beyond coxa, apical margin convex, flat on top; apex slightly widened; punctate, with preapical depressions. Width of prosternal intercoxal process 1.4–6.2 times the distance between the anterior margin of prosternum and the coxal cavity ( Fig. 65 View Figures 65–68 ). Distance between anterior margin of prosternum to end of intercoxal prosternal process 1.7–8.7 times the width of the prosternal intercoxal process. Prosternum 1.0–2.9 times as long as the mesosternum, 0.5–0.8 times as long as metasternum ( Fig. 66 View Figures 65–68 ). Proendosternite in T. metallicus about as long as broad, with the top bluntly angulate laterally. Pro- and mesotibiae dorsally convex, without apical spine. Visible part of mesoscutellum flat, triangular, and extremely minutely punctate. Mesosternal intercoxal process more or less transversely depressed in the middle. Width of mesosternal intercoxal process 2.0–4.8 times the distance between the anterior margin of the mesosternum and the coxal cavity ( Fig. 66 View Figures 65–68 ). Distance from anterior margin of mesosternum to end of intercoxal mesosternal process 0.6–1.1 times the width of the mesosternal intercoxal process. Mesendosternite in T. metallicus narrow basally, broadened in middle, and apically narrowed like a thread ( Fig. 67 View Figures 65–68 ).

Elytra with well-developed humeral callus, punctures confused, often forming uncountable rows. Ventral surface of elytron with three sensilla patches in T. metallicus : anterior as well as middle near lateral margin, posterior near apex. Elytral epipleuron extending beyond three-quarters of elytron, not reaching apex, oblique, with maximum width subequal to that of the midfemur. Wings with full set of veins. Metanotum fully developed with allocrista as long as medial groove, ridge joins distal end of b 2 in T. metallicus ( Fig. 69 View Figures 69–75 ).

Metasternum with anterior margin convexly arched, and raised sharply between mesocoxae, posterior margin bisinuate, and raised on either side of discrimen, forming a pair of distinct protuberances distally raised far above the level of the metacoxa ( Fig. 66 View Figures 65–68 ). Metendosternite with short stalk, shorter than basal width of arm in T. metallicus ( Fig. 68 View Figures 65–68 ).

Metafemur robust with proximal third of anterior margin strongly convex, posterior margin not distinctly convex. Metatibia apparently straight in lateral view, characteristically curved, with ends towards lateral side in dorsal view, gradually widening from proximal end to distal end, dorsally more or less flat, distinctly margined on either side, lateral as well as mesal margins bear row of thick bristles distally, lateral row longer than one-third of the metatibia, mesal edge with similar bristles along apex only, tarsal articulation on well-developed callosity visible in lateral view; proximal to tarsal articulation, circular concavity with a broad, flat denticle on either side. First metatarsomere as long as or longer than half of metatibia, more or less laterally flattened, subequal to or longer than the rest of the tarsomeres combined, ventral side densely covered with thin, pointed setae, different from those on dorsal side, with setae often sexually dimorphic. Metatibial spine articulated at middle of apex, thick, sharp, and dorsolaterally directed. Second metatarsomere longer than third, distally wider than proximally, setae on ventral side not as dense as in first metatarsomere, pointed, and crowded towards distal region of ventral side; third metatarsomere bilobed, setae on ventral side feather like and dense; claw tarsomere apparently two times as long as third metatarsomere. Claw appendiculate, and nearly as long as the metatibial spine. First abdominal ventrite with a pair of characteristic subparallel ridges medially, joining anteriorly in the intercoxal region of the ventrite to form a shape like ‘o’. Apical tergite of female proximally with a pair of sensilla patches and a shallow longitudinal groove along the middle, not reaching the apex; the groove may be absent, and the sensilla patches may be poorly developed, in some species.

Spermatheca with distinct pump, receptacle, and duct; receptacle longer than wide, longer than pump; duct long, convoluted; vaginal palpi with distinct anterior and posterior sclerotization beside lateral unsclerotized area, medial margin fused for a short distance. Tignum channelled along middle, posterior sclerotization broader than anterior sclerotization.

In ventral view, median lobe of aedeagus with proximal end deeply cleft, ventral surface often convexly raised, apex broad or obtuse, never acutely pointed; in lateral view, moderately curved.

Sexual dimorphism: Members of Tegyrius exhibit unusual sexually dimorphic characters. Posterior margin of the last visible ventrite of males is bisinuate, with a lobe in the middle in all of the species. The posterior margin of the last ventrite in females is entire except in Tegyrius anupama sp. nov., which has a deep circular incision with an acute process in the middle ( Fig. 17 View Figures 15–21 ). The first pro- and mesotarsomeres are slightly wider in males than in females. The mesotibia is distally enlarged and curved in males in the two species from India. The first metatarsomere is sexually dimorphic in the Sri Lankan species. The colour of the fore- and middle legs and the last abdominal ventrite are sexually dimorphic in T. keralaensis comb. nov.

Larva: Unknown.

Remarks: Tegyrius and Lanka belong to a group of genera with a pair of subparallel ridges along the middle of the first abdominal ventrite, and with a characteristically curved metatibia with a flat dorsal surface. This unique group, which is probably monophyletic, is represented in the Indian subcontinent by Philogeus Jacoby , Bikasha Maulik , and Lankaphthona Medvedev , besides Lanka and Tegyrius . Differential diagnoses and a key to these genera are provided in our work on Lanka ( Prathapan & Viraktamath, 2008) .

An antebasal transverse impression on the pronotum is a character commonly used at the generic level in the classification of flea beetles. Konstantinov (1998), using Aphthona , has shown that a simple antebasal transverse impression is of little value in separating genera. Our studies on Tegyrius underscore his contention that this character could be variable among congeneric species. Four species of Tegyrius completely lack the antebasal transverse impression that is present in other species at varying degrees of development.

Although Tegyrius is common in the Sri Lankan subregion, one of us (PKD) failed to collect them on Piper in the Himalayas. This is a strong indication of the Oriental origin of the genus. No flea beetle was observed on Peperomia Ruiz & Pavon , although they are common and next to Piper in diversity and abundance among the Piperaceae in the subcontinent.