Semiothisa, HUBNER, 1818

Scoble, Malcolm J. & Krüger, Martin, 2002, A review of the genera of Macariini with a revised classification of the tribe (Geometridae: Ennominae), Zoological Journal of the Linnean Society 134 (3), pp. 257-315 : 288

SEMIOTHISA HÜBNER

(Figs 21–23, 136–138)

Semiothisa Hübner (1818) . Type species: Semiothisa gambaria Hübner, 1818 . Surinam .

Description

Head. Male antenna not bipectinate. Chaetosemata extended across head as a line of setae; meeting.

Wings (Figs 21–23). Forewing typically falcate; hindwing often slightly produced. Colour and pattern variable, ranging from brown to buff.

Male genitalia ( Fig. 136 ). Uncus subtriangular; horns and stout setae lacking. Gnathos: medial process well developed. Valva: costa a very narrow, curved, spinelike structure with a setose knob at its base; sacculus broad.

Pregenital abdomen of male ( Fig. 137 ). Sternum A8 deeply cleft rendering it bilobed; lobes rounded or more pointed, but not produced.

Female genitalia ( Fig. 138 ). Bursa copulatrix: ductus bursae broad and hardly distinguishable from corpus bursae; signum present.

Diagnosis. Distinguished from all genera without uncus horns, except Oxymacaria , by the presence of a narrow, curved costa. The presence of a setose knob at the base of the costa enables Semiothisa to be distinguished from Oxymacaria , as does the absence of bipectinate antennae in Semiothisa . Unlike the condition in Oxymacaria where sternum A8 is hardly modified, in Semiothisa sternum A8 is bilobed. Hair-like scales arise from each side of the intersegmental membrane of A8 and A 7 in Semiothisa , and Semiothisa has chaetosemata extended across the head, unlike the condition in Oxymacaria .

The wing pattern exhibited by Semiothisa species frequently is similar to that in species of Macaria . The genitalia, however, are quite different.

Comments. The macariine association of Semiothisa is evident from the wing pattern, the divided valva, the extended chaetosemata and the cleft condition of sternum A 8 in the male. Although it lacks uncus horns, the cleft condition of sternum A8 and the wing pattern, which occurs so widely in Macariini (e.g. Fig. 21) suggests that Semiothisa might be closely related to Macaria with the horns having been lost secondarily.

Semiothisa has been used as the generic name for species in many parts of the world, sometimes to cover a large part of the Macariini . In fact, Semiothisa s. str. is a very distinctive and homogeneous genus in terms of its male genitalia, as was noted by Inoue (1986: 260).

Distribution. Neotropics.

Number of species. Nineteen species have been identified as belonging to Semiothisa , including a few additions to those listed by Parsons et al. (1999).

Figures

Figures 136–138. Semiothisa gambaria: 136, ♂ genitalia; 137, sternum A8 of ♂; 138, ♀ genitalia.