Miroblatta baai Grandcolas

Grandcolas, Philippe & Deharveng, Louis, 2007, Miroblatta baai, a new very large cockroach species from caves of Borneo (Blattaria: Blaberidae), Zootaxa 1390, pp. 21-25 : 21-24

Miroblatta baai Grandcolas , new species

( Figs. 1–9 )

Diagnosis. Miroblatta baai is similar to Miroblatta petrophila Shelford, 1906 but can be distinguished by smaller eyes, slender shape with longer pronotum showing one remarkable central bulbous structure, shorter wings, longer legs, narrower abdomen, more specialized male subgenital plate, more simple L1 sclerite in male genitalia.

Description. Head globulous with protruding vertex, partly hidden by pronotum, eyes small, not closer to each other than to antennal sockets. Antennae longer than body, with darker part from basis to first quarter, this dark portion not extending beyond pronotum.

Pronotum ( Fig. 2 ) characteristic of genus, highly specialized, with one median carina beginning above head, ending with remarkable bulbous structure and dividing latter into two carinae. Slightly longer than broad, with lateral and posterior margins sinuous.

Wings short, extending not far beyond mid­length of abdomen. Forewings ( Fig. 3 ) roughly oval with posterior margin clearly rounded, not totally overlapping in mid of dorsum, with subcostal fields well developed and slightly folded relative to remainder of tegmen. Hind wings ( Fig. 4 ) folded into two parts, with vannus flat (without fan­like fold).

Legs very long and slender without spines on femora; tarsi long, without arolia.

Abdomen ( Fig. 1 ) elongated, more than twice as long as its maximal width. Supra­anal plate ( Fig. 8–9 ) with posterior margin weakly rounded. Male subgenital plate ( Fig. 8 ) asymmetrical, with notch on right where singular stylus is placed; stylus short, and poorly sclerotized, pale. Female subgenital plate ( Fig. 9 ) very long, with posterior margin symmetrically rounded. Cerci ( Fig. 8–9 ) long and slender.

Colouration dark red­brown, with abdomen tawny yellow, but posterior, exposed parts of dorsal side also red­brown (tawny yellow on terga visible between bases of wings); legs orange­brown.

Male genitalia ( Fig. 5–7 ): Blaberid­like with three phallomeres, cleft on right, penis in middle, and hook on left. Penis L1 with separate apex, shaped as tooth curved to left, with several denticles on right side only. Hook L2d strong and short. Cleft R2 ( Fig. 7 ) large, deep and slightly curved, connected laterally to conspicuous sclerite R3d, ventrally to elongated and slender sclerite R 3v and innerly to large sclerite N quite well­sclerotized.

Female genitalia: Blaberid­like, with large incubating pouch (brood sac) on ventral side.

Holotype, ɗ, Indonesia, East Kalimantan, Ambulabung cave (=Gua) in the Baai underground river system, 15 August 2004 (Yayuk Suhardjono, L. Deharveng, A. Bedos, C. Rahmadi), Bogor Museum, Indonesia. Allotype: Ψ, Idem, Muséum national d’Histoire naturelle, Paris. 2 nymphs, Idem, Bogor Museum, Indonesia. 1 nymph, Idem, Muséum national d’Histoire naturelle, Paris. 1 large male nymph, Kepayan, Baai underground river system, East Kalimantan, Indonesia, 7 February 2000 (Franck Tessier), Muséum national d’Histoire naturelle, Paris.

Distribution. Indonesia: Borneo, East Kalimantan.

Etymology. The species name is taken from the underground river system Baai (Borneo, East Kalimantan, Indonesia).

Measurements. Body length: ɗ: 51 mm; Ψ: 65 mm. Pronotum length: ɗ: 19 mm; Ψ: 19 mm. Wing length: ɗ: 20.5 mm; Ψ: 22 mm.

M. baai shows the same uncommon combination of features as M. petrophila : femora without spines, hind wings without a fan­like fold, the female subgenital plate without valvulae. This combination does not fit the old and traditional taxonomic definitions of cockroach family groups ( Princis 1960). In this definition, hind wings without fan­like fold characterize the family Polyphagidae , the female subgenital plate without valvulae does not fit the family Blattidae , but the family Blaberidae , despite the femora being unarmed. This unique combination of characters may explain frequent changes of the taxonomic position of the genus Miroblatta .

The genital morphology of this genus shows all characters synapomorphic of the family Blaberidae , including the ovoviviparity, according to the more recent family concepts from McKittrick (1964), Roth (1970, 2003) and Grandcolas (1996). This may indicate that species of Miroblatta have lost the fan­like fold of hind wings and the spines on the femora which are present in most Blaberidae cockroaches ( Grandcolas 1993). This situation is not totally unique in the family Blaberidae as the genera Hormetica Burmeister, 1838 and Parahormetica Brunner von Wattenwyl, 1865, deeply nested within the neotropical subfamily Blaberinae ( Grandcolas 1998), also show such a loss of the fan­like fold in the hind wings. As for the evolution of spines on legs, to our knowledge no other extreme cases have been described and the only comparable and deep change that we know of is the loss of one out of three rows of spines on the posterior tibiae in the genus Aptera Saussure, 1864 ( Princis 1960; Grandcolas 1997). Finally, the shape of the right phallomere shows the sclerite R2 (cleft) with the inner part slightly shorter than the outer part, which tentatively characterizes the subfamily Epilamprinae ( Grandcolas 1993; but see Anisyutkin 2003).

M. petrophila was found running among stones on the ground in the tropical forest ( Shelford 1906). M. baai has a different habitat since all captures took place only in caves of the same karstic system of the Baai underground river. The Baai river sinks at Kepayan cave, flows underground for several kilometers, and resurges at Ambulabung cave. The distance between the sink and the resurgence is more than 4 km in a straight line. More than 15 km of passages have been explored in caves connected to this system ( Robert 1990; Jones 1996). In several of them, cavers reported the presence of Miroblatta , but they did not catch the specimens (Robert comm. pers.). So far, cockroaches similar to Miroblatta have never been reported from other caves of East Kalimantan ( Lips 2002), and in the caves of other karsts of Borneo investigated for cave fauna ( Roth 1980; Chapman 1984; Rahmadi & Suhardjono 2004). Other caves in East Kalimantan or in Sarawak ( Roth 1980), of which the fauna has been studied are not known to harbour this species.

M. baai was found on the walls of the caves, as isolated specimens or in groups of 2–3. They were not observed in guano accumulations. Therefore, it does not seem to be an opportunistic guanobitic species living in hollowed trunks and only secondarily occurring in caves as many blaberid species do ( Chopard 1938; Izquierdo & Oromi 1994; Grandcolas 1998; Pellens et al., 2006; Roth & Naskrecki 2004).

This likely troglobiosis is corroborated by the morphological examination of M. baai and the comparison to its close, non­troglobitic relative M. petrophila Shelford, 1906 and other species belonging to the subfamily Epilamprinae ( Grandcolas 1996): legs are longer, eyes smaller, wings shorter and the body colour is paler, all characters supporting a hypothesis of troglobiomorphosis.

Little is known about the behavior of the new species, but individuals of M. baai have been observed standing upward on their long legs, moving quite slowly with some moderate acceleration bursts when disturbed. The head was particularly mobile and was oriented strongly backward or laterally when grooming and, in this respect, the most common antenna grooming behavior in blaberids (unassisted antenna cleaning with mouthparts only) was commonly observed in M. baai (Bobula­Smith & Valentine 1985) .

This is the first documented case of troglobiosis and troglobiomorphosis in a large­sized cockroach belonging to the family Blaberidae up to date. All previous captures of Blaberidae cockroaches in caves were of burrowing, guanobitic or even man­imported species (pers. obs.) Most other troglobitic species are smallsized and belong to the families Nocticolidae (e.g., Roth 1980, 1988; to be merged with the family Polyphagidae , pers. obs.), Anaplectidae (pers. obs.), Blattellidae , and Pseudophyllodromiidae (e.g., Fisk 1977; Roth 1988).

Figures

FIGURES 1 – 9. Miroblatta baai sp. nov..; 1. Adult male habitus; 2. Male pronotum; 3. Male forewing; 4. male hind wing (at rest, folded into two parts with the vannus flat); 5. Male genitalia, dorsal view; 6. Apex of sclerite L 1 of male genitalia; 7. Right phallomere (cleft) of male genitalia; 8. Ventral view of the posterior part of male abdomen with cerci, subgenital plate and posterior margin of supra­anal plate; 9. Ventral view of the posterior part of female abdomen with cerci, subgenital plate and posterior margin of supra­anal plate; L 1, L 2 d (hook), R 2 (cleft), R 3 d, R 3 v, N: sclerites of male genitalia; sgp: subgenital plate; sap: supra­anal plate; st: stylus.