Tachyta (Paratachyta) wallacei (Andrewes 1925)

Tachyta wallacei (Andrewes)

Tachys wallacei Andrewes, 1925:164 [holotype, female, in BMNH; type-locality: New Guinea].

DIAGNOSIS.—The reflexed pronotal margins, lack of microsculpture, and indications of striate-punctate elytral interneurs are distinctive in the genus.

DESCRIPTION.—Form (Figure 5): Short, robust, and highly convex. Pronotum quadrately cordiform; elytra inflated especially at apical third where widest, sides arcuate, narrowly rounded at apex.

Color: Shiny rufopiceous dorsally, rufous or rufotestaceous ventrally. With or without vague spots humerad and at apical third of elytron. Appendages testaceous.

Head (Figure 26): Smaller and narrower than the three preceding species, with more deeply engraved frontal furrows and a tendency for transverse frontal wrinkles; mouthparts as in members of T. acuticollis except mentum (Figure 25), which is deeply sulcate anteriorly.

Pronotum (Figure 27): Quadrately cordiform, sides strongly sinuate basally, hind angles strongly acute; basal transverse impression deeply engraved, sinuate, and curved anteriorly medially where it is broadly interrupted; disc highly convex to lateral ridge and with deeply engraved median longitudinal impression, sides broadly reflexed.

Elytra (Figure 28): As in members of T. acuticollis except more convex, suturai interneur striate and entire, and disc with traces of striate-punctate interneurs in basal half.

Microsculpture: Absent from dorsal surface, except labrum.

Genitalia (Figure 9): Male median lobe most similar to members of T. philipi except with broader and more rounded apex. Endophallus with apical structures narrowly rounded, and curved; C-shaped sclerite well developed. Female stylus as in Figure 13.

Size: Length, 1.90 to 2.18 mm; width, 0.88 to 1.00 mm, 3 specimens measured.

NATURAL HISTORY.—Darlington (1962) states “My specimens were taken by beating foliage, especially dense clumps of leaves or moss-like epiphytes on the branches of low trees in the understory of rain forest.” Specimens have been collected in the months March through October; no teneral specimens seen. Specimens were collected between sea level and 1000 m elevation.

DISTRIBUTION (Figure 29).—This species is widely distributed throughout New Guinea.

DIAGNOSIS.—With the characters listed for the genus plus dorsal surface microreticulate, elytral interneurs variously present but at least 1–3 feebly striate, and dorsal setae not thick.

The umbrosa group

Members of the umbrosa group are characterized by their broad and depressed form, elytral chaetotaxy with Ed 6 in position b (fourth interneur), and transversely meshed microreticulation. In addition, male members have a lightly pigmented and noncomplex endophakllus. One member has bicolored elytra, another member has short but clearly visible pubescence.

Three of the four species representing this group have been found under bark of logs, while the fourth is known only from two specimens without habitat labels. The larval stage of T. umbrosus is known (Gardner, 1938).

The four species of the group have a combined range extending from Sri Lanka (Ceylon) and northern India east to the Japanese Ryu Kyu Islands, south through New Guinea to northern Queensland, Australia, and east to the Solomons. This large range is that of one of the species, T. umbrosa; the other three species have very small ranges, within the area already delimited.