Euborellia janeirensis (Dohrn, 1864)

Kamimura, Yoshitaka & Ferreira, Rodrigo L., 2017, Earwigs from Brazilian caves, with notes on the taxonomic and nomenclatural problems of the Dermaptera (Insecta), ZooKeys 713, pp. 25-52 : 33-35

Euborellia janeirensis (Dohrn, 1864) Figs 23-28

Material examined.

3 ♂♂, 6 ♀♀, 7 nymphs, Gruta dos Farias cave , Barbalhas, Ceará, 30.iv.2007, Ferreira, RL leg. ( ISLA 15565) - 1 nymph, Cave GEM-1623, Parauapebas, Pará, 16.iii.2011, CARSTE leg. ( ISLA 21085) - 1 nymph, Gruta Ecos cave, Cocalzinho de Goiás, Goiás, 4.iv.2006, CECAV leg. ( ISLA 21096) .

Association with caves.

While most earwigs found in Brazilian caves seem to be accidental, this species was present as a large population within Gruta dos Farias cave, a sandstone cave located in Barbalhas municipality ( Ceará state, Brazil). Many adults and nymphs were observed only in guano piles in deeper areas of the cave, which has a stream trespassing its entire conduit, strongly suggesting that the population is troglophilic. They are likely feeding on bat guano or preying upon small invertebrates.

Description and remarks.

All adult specimens examined in this study had fully developed tegmina, but lacked hind wings. Four species of Euborellia from the Neotropical region, E. boliviana Brindle, 1971, E. ambigua (Borelli, 1906), E. caraibea Hebard, 1921, and E. janeirensis , also have such characteristics. Among these species, E. janeirensis is distinguished from the others by the presence of well-developed lateral longitudinal ridges on the male abdominal tergites VI and IX, and one or more white/yellow distal antennal segments ( Steinmann 1989a). The external morphologies and male genitalia of the specimens examined in this study agreed well with those described previously for E. janeirensis , including brown markings on the femora (Figs 23 and 27 ), the shapes of the forceps (Figs 23 and 27 ), and the shapes of the parameres and denticulated pads in the penis lobe (Fig. 26 ).

Taxonomists generally examine only the terminal region of the male genital organs. The male genitalia of E. janeirensis were approximately 22 mm in length, and more than twice the body length with forceps (Fig. 25 ). The manubrium, which is an extension in the basal, inner margin of the penultimate sternite ( Burr 1915b; Ramamurthi 1958), was approximately 6 mm in length (Fig. 24 ). In male earwigs, the retractor muscles of the genitalia originate from this structure ( Popham 1965a). As reported by Mariani (1994), the spermatheca of this species was a long and thin blind duct lacking a capsule at the distal end (Fig. 28 ).

Males of Euborellia spp. directly insert the elongated virga into the female spermatheca during copulation ( Kamimura 2000; Lieshout and Elgar 2011). Elongation of the virga (and the genitalia as a whole, which functions as the virgal sheath when in repose) is considered an adaptation for removal of rival sperm from the female spermatheca, which is usually longer than the virga ( Kamimura 2000, 2005, 2013, 2015; Lieshout and Elgar 2011). Thus, genital elongation in E. janeirensis suggests intensive sperm competition in this species.

Distribution.

Brazil, Argentina, Paraguay, and Venezuela.

Figures

Figures 23 - 35. 23 - 26 Euborellia janeirensis (male): habitus (23), penultimate sternite + manubrium (24), and genitalia (25, 26) 27 - 28 Euborellia janeirensis (female): habitus (27), and spermatheca (28) 29 - 32 Euborellia brasiliensis (male): habitus (29), penultimate sternite + manubrium (30), and genitalia (31, 32) 33 Anisolabididae gen. sp. 1 (female): habitus 34 Anisolabididae gen. sp. 2 (nymph): habitus 35 Anisolabididae gen. sp. 3 (nymph) habitus. Scale bars 3 mm for Figs 23 - 25, 27, 29, 30, 33 - 35; 0.5 mm for Figs 26, 28, 31; 100 μm for Fig. 32.