Thaumastaneis montandoni Kirkaldy and Edwards 1902

Dellapé, Pablo Matías & Melo, María Cecilia, 2007, Thaumastaneis nigricans, a new species of a remarkable ant-mimetic Larginae (Hemiptera: Largidae) and the discovery of an ant-mimetic complex, Zootaxa 1475, pp. 21-26 : 24-26

Thaumastaneis montandoni Kirkaldy and Edwards 1902

( Figs 7–17 )

Until now nothing has been reported about the biology of this species. Van Doesburg (1966) only mentioned that “the strongly ant-like appearance suggests some relation with ants”. The authors collected in Ituzaingó, Corrientes prov. ( Argentina) several adults of T. montandoni ( Fig. 17 ) (deposited in MLP).

Scanning electron microscopy shows some structural modifications that enhance mimicry: silvery reflective hairs on lateral regions of the hemelytra ( Fig. 12 ), pitted areas on the neck (fig. 13), and thoracic spines ( Fig. 14 ).

Van Doesburg (1966) and Schaefer (2000) described the antennae, tibiae, and tarsi of T. montandoni as light brown or yellowish brown. These structures are reddish in the field and in recently collected specimens, although after a short time we observed they had turned to light brown.

We also note that although Schaefer (2000) described in Thaumastaneis montandoni fifth instar as having only two dorsal abdominal scent gland openings (between terga III–IV and IV–V), we find three in the adults of both species of Thaumastaneis, the third lying between terga V–VI. Moreover, the first gland appears to be functional ( Figs. 15–16 ).

Associated with T. montandoni we collected adult workers of a species of the ant genus Camponotus ( Fig. 18 ) ( Hymenoptera : Formicidae ), as well as an undescribed species of myrmecomorphic cricket ( Fig. 19 ) ( Orthoptera : Trigonidiidae ). The general color of these species is black, with particular regions of the legs reddish: coxae, trochanters, and femora in the ants; femora and tarsi in the cricket. This color pattern and the antlike appearance of both the heteropteran and the orthopteran suggests the presence of a mimetic complex.

We also record Thaumastaneis montandoni for the first time from Paraguay, Dept. San Pedro, Carumbé; the specimens examined (2 males, 3 females) belong to the Instituto Miguel Lillo Entomological Collection.

Figures

FIGURES 2 – 11. Thaumastaneis sp., male genitalia. (2 – 6) Thaumastaneis montandoni Kirkaldy & Edwards. (2) pygophore, dorsal view; (3) right paramere, outer view; (4) right paramere, inner view; (5) aedeagus, anterior view; (6) aedeagus, lateral view; (7 – 11) Thaumastaneis nigricans n. sp. (7) pygophore, dorsal view; (8) right paramere, outer view; (9) right paramere, inner view; (10) aedeagus, anterior view; (11) aedeagus, lateral view.

FIGURES 12 – 16. Thaumastaneis montandoni Kirkaldy & Edwards. (12) scutellum and hemelytra, dorsal view; (13) detail of the pitted areas on neck; (14) head and thorax, dorsal view; (15) abdomen, dorsal view; (16) detail of abdominal scent gland opening between abdominal segments III and IV.

FIGURES 17 – 19. (17) Thaumastaneis montandoni Kirkaldy & Edwards; (19) Camponotus sp. (19) Trigonidiidae cricket sp.