Thyestetha Pascoe, 1865

Eberle, Jonas, Tänzler, Rene & Riedel, Alexander, 2012, Revision and phylogenetic analysis of the Papuan weevil genus Thyestetha Pascoe (Coleoptera, Curculionidae, Cryptorhynchinae), Zootaxa 3355 (1), pp. 1-28 : 3-4

Thyestetha Pascoe, 1865

Type-species: Thyestetha nitida Pascoe , by monotypy.

Diagnosis. Fully apterous genus of Cryptorhynchinae . Length. Pronotum + elytra 2.8–5.4 mm. Body subglabrous, ventral surface and legs sparsely squamose. Rostrum long, in repose reaching hind level of mesocoxae, overhanging metaventrite. Antennae inserted in apical third of rostrum, scape longer than funicle. Pronotum basally bordered by row of punctures. Scutellum externally absent. Elytra smooth, with 9 striae; interval 10 mesally raised, laterally crenate. Mesothoracic receptacle (Fig. 24) posteriorly open. Metanepisternum ( Figs. 23a–b ) triangular, squamose. Femora long, subapically with one tooth.

Notes. Some species of Trigonopterus are superficially similar, but can be easily distinguished by the absence of the metanepisternum, the much smaller tarsal claws and the posteriorly closed mesothoracic receptacle. Elichora is probably closely related to Thyestetha and can be distinguished by a transverse row of deep punctures along the elytral base and by the posteriorly closed mesothoracic receptacle. Species of Telaugia can be separated by their shorter and stouter rostrum not passing the mesoventrite in repose and by their simple metafemoral apex which is lacking a stridulatory patch.

Description. Length. Pronotum + elytra 2.8–5.4 mm.

Color black, with or without metallic bluish lustre; antenna and tarsi ferruginous. Integument of elytra and pronotum polished, nude; ventral surface and legs sparsely squamose. Habitus subovate to subrhomboid or subglobous, almost without constriction between prothorax and elytra; body in profile between pronotum and elytra dorsally with shallow constriction. In thanatosis ( Figs. 19, 20 ) legs forming compact unit, sticking out from horizontal body plane at ca. 45°; mesofemur projecting over pro- and metafemur.

Rostrum long, in males ca. 4.7–5.6 X as long as wide at base, in females ca. 4.6–6.3 X as long as wide at base; in repose reaching hind level of mesocoxae, overhanging metaventrite; weakly curved, almost straight; in dorsal aspect sides subparallel, widest at base and shortly before apex. Antennal insertion in apical third. Antennal scrobe dorsally bordered by furrow containing row of scales, scales larger near eye. Dorsum posteriorly sparsely punctate, nude; anteriorly in front of antennal insertion subglabrous. Cross-section subovate. Head. Eye large, subtriangular ( Fig. 21 ), in thanatosis partly exposed. Dorsal margin of eye bordered by distinct furrow. Forehead between eyes narrower than rostral base (0.7 X), densely punctate; vertex behind eyes glabrous. Antennal scape longer than funicle, in repose almost reaching eye; funicle with 7 articles; articles 1 and 2 elongate, subequal in length; articles 3–7 shorter, decreasing in length, article 7 ca. as long as wide; club elongate-ovate.

Pronotum in dorsal aspect subtriangular; 1.14–1.33 X wider than long, widest at base; sides markedly converging to apex in convex line, subapically more or less concave; without basal or subapical constriction; disc convex, subglabrous, basally bordered by row of coarse punctures containing microreticulation, sometimes scattered punctures forming indistinct second row; at least in anterior half punctate; nude except for minute setae contained in punctures; interstices between punctures smooth, polished; in lateral aspect with rounded postocular lobe; anterior dorsal margin extended covering vertex; ventrally along marginal carina with scales. Scutellum externally absent.

Elytra smooth, without prominences; subglobose; basal margin weakly concave; 0.89–1.14 X wider than long, 1.05–1.15 X wider than base of pronotum, widest in basal 0.16–0.29 of elytral length; profile dorsally smoothly convex, ca. as deep as long; 9 striae marked by more or less distinct rows of punctures, in some species punctures partly effaced, stria 1 not reaching elytral base, stria 9 adjacent to lateral elytral margin except in apical 1/5, where additional short row of punctures bordering lateral margin; intervals flat, glabrous, polished; along base simple, without transverse row of enlarged punctures; lateral interval 10 mesally raised, laterally crenate; lateral margin markedly sinuate, convex at humerus, concave above metacoxa; females with apex in profile constricted, extended beak-like ventrad (Fig. 25); males with apex simple. Elytral strigil completely absent. Median suture interlocked. Lateral suture interlocked with thorax and abdominal ventrites 1–2.

Thoracic venter ( Figs. 22 , 24). Integument dull, microreticulate, coarsely punctate, sparsely covered with white recumbent or erect scales and setae. Ventral setose fringe of pronotal hypomeron simple, at middle briefly interrupted. Procoxa with tooth posteriorly defining rostral canal. Rostral canal anteriorly widening to junction with postocular lobes, abruptly narrowed by inward directed teeth. Mesothoracic receptacle open behind (Fig. 24), anteroventral edges sharply protruding; medially surface even with concave disc of metaventrite. Mesocoxa and metacoxa simple, without marked teeth, approximate. Suture between meso- and metaventrite effaced. Metaventrite medially broadly concave and weakly punctate; between meso- and metacoxa with depression bordered by ventral and lateral prominences. Mesepimeron and mesanepisternum large, subglabrous. Metanepisternum triangular, squamose ( Fig. 23 ).

Legs. Femora parallel-sided, ventrally weakly sulcate, anteroventral ridge distinct, subapically terminated by concave impression (Fig. 28), in apical third with tooth; at least dorsally with whitish scales, metafemora basally with squamose line forming a patch of scales in apical third; ventral surfaces nude except one row of scales bordering anteroventral ridge; metafemur apically projecting beyond elytral apex, subapically with stridulatory patch of transverse relatively coarse parallel wrinkles; males in apical third of posterior face with concavity basal to stridulatory patch. Tibiae with longitudinal ridges; sulci between ridges containing regular rows of whitish scales; apically with distinct uncus and minute premucro. Tarsal claws stout.

Abdomen. Ventrite 1 medially concave, at least laterally squamose; intercoxal process much wider than long, interlocked with metaventrite. Ventrite 2 with convex anterior margin; suture between ventrites 1–2 distinct. Ventrites 3–4 narrow, of equal length, glabrous. Ventrite 5 flat, subglabrous except laterally and apically sparsely setose.

Male terminalia ( Figs. 29–54 ). Tergite VII ( Figs. 29, 32 ) 0.85–1.20 X wider than long; posterior margin deeply emarginate; anterior margin convex; sparsely setose, simple, without microsetae or denticles. Tergite VIII ( Figs. 31, 34 ) 1.33–2.08 X longer than wide, apically weakly rounded, densely setose. Sternite VIII divided into pair of subtriangular sclerites, medially membranous. Spiculum gastrale long, longer than apodeme of aedeagus, apically weakly curved. Tegmen ( Figs. 29, 32 ) with apodeme shorter than width of ring; parameroid lobes converging in straight line, fused in basal half. Aedeagus ( Figs. 37–54 ) dorsally with median ridge, apex curved ventrad; ostium with median sclerites and pair of lateral sclerites; median sclerites folded repeatedly in repose ( Figs. 35, 36 ); ventral membrane extensively sclerotized; ductus ejaculatorius simple.

Female terminalia ( Figs. 55–65 ). Tergite VII ( Figs. 57, 60 ) 1.44–2.23 X longer than wide; posterior margin convex, densly setose; lateral margins converging apically. Tergite VIII ( Figs. 56, 59 ) 1.88–2.73 X longer than wide, posterior margin convex, markedly crenulate. Sternite VIII ( Figs. 55, 58 ) apically emarginate, lateral lobes with few long setae, apodeme ca. 1.5 X longer than apical plate. Hemisternites of ovipositor ( Figs. 63–65 ) 5.25–10.75 X longer than wide, longer than apical plate of sternite VIII; styli apically setose. Spermatheca ( Fig. 62 ) strongly curved, insertion of spermathecal duct at junction of bursa copulatrix and oviduct; more or less distinct bursal sclerite at insertion of spermathecal duct.

Figures

FIGURE 23 a – b. Thyestetha nitida, pleural sclerites; c 2 mesocoxa, c 3 metacoxa, el elytron, epm 2 metanepimeron, eps 2 mesanepisternum, eps 3 metanepisternum, mr mesothoracic receptacle, s 3 metaventrite. Fig. 23 c. Mesothoracic receptacle of Elichora sp.; Figs. 24 – 28. Thyestetha spp.: (24) T. glabra sp. n., detail of mesothoracic receptacle, ventral view. (25) T. lubrica sp. n., female elytral apex in profile; arrow marking subapical constriction. (26) T. carbonaria, male metafemur, arrow marking protrusion of posteroventral ridge; (27) T. puncticollis sp. n., male metafemur with weakly protruding posteroventral ridge (28) T. lubrica sp. n., left metafemur, arrow marking subapical concavity.

FIGURES 19 – 22. Thyestetha spp.: (19) T. glabra sp. n., thanatosis position, lateral aspect, (20) T. glabra sp. n., thanatosis position, ventral aspect. (21) T. puncticollis sp. n., eye, anterolateral aspect. (22) T. glabra sp. n., ventral aspect.

FIGURES 29 – 36. Male terminalia of Thyestetha spp.: (29 – 31) T. glabra sp. n., holotype: (29) tegmen, (30) tergite VII and (31) segments VIII – IX. (32 – 34) T. nitida: (32) tegmen, (33) tergite VII and (34) tergite VIII with sternite VIII and spiculum gastrale. Ostium, lateral aspect: (35) T. discolor sp. n., arrow and dashed line marking bulge between 2 nd and 3 rd fold (36) T. splendens sp. n..

FIGURES 37 – 54. Aedeagus of Thyestetha spp. in dorsal and lateral aspect: (37, 38) T. carbonaria, lectotype; (39, 40) T. discolor sp. n., holotype; (41, 42) T. glabra sp. n., holotype; (43) T. carbonaria, apex of aedeagus, ventral aspect; (44) T. oblita sp. n., holotype, apex of aedeagus, ventral aspect; (45, 46) T. lubrica sp. n., holotype; (47, 48) T. nitida, lectotype; (49, 50) T. oblita sp. n., holotype; (51, 52) T. puncticollis sp. n., holotype and (53, 54) T. splendens sp. n., holotype.

FIGURES 55 – 60. Female terminalia of Thyestetha spp.: (55 – 57) T. emarginata sp. n., holotype: (55) sternite VIII, (56) tergite VIII and (57) tergite VII. (58 – 60) T. nitida: (58) sternite VIII, (59) tergite VIII and (60) tergite VII.

FIGURES 61 – 65. Female genitalia of Thyestetha spp.: (61 – 63) T. emarginata sp. n., paratype: (61) tripartite sclerite at insertion of spermathecal duct. T. emarginata sp. n., holotype: (62) Spermatheca. (64 – 65): T. nitida (64) ovipositor, lateral aspect.