Austrospirachtha carrijoi Zilberman & Pires-Silva 2023, sp. nov.

Austrospirachtha carrijoi Zilberman & Pires-Silva sp. nov.

Measurements: Female (Figs. 1–2)—about 2.4 mm from the curvature of the abdomen to the apex of mandibula.

Male unknown.

Body highly physogastric, with constrictions and three pairs of pseudoappeandages; sclerotized parts light to dark brown. Maxilla with first palpomere distinct (Fig. 3D), and post-mentum with two distinguishable main pairs of bristles (Fig. 5A). Abdominal segment III inflated into an ovoid region, longer than the subsequent segments combined; sternite V with secondary sclerotization on distal and lateral margins (Fig. 4C); sternite VI with sinuous secondary sclerotization on distal margin (Fig. 4D).

Head slightly wider than long, overall, seemingly subquadrate (Fig. 3A); anterior region of vertex highly impressed, leaving areas above eyes seemingly carinated; posterior margin on lateral view with one notch (Fig. 1A). Gula broad, expanding posteriorly with occipital region occupying greater portion of total head width (Fig. 3). Antenna with 11 antennomeres, scape almost as long as antennomeres 2–4 combined; antennomeres 5–10 subquadrate; antennomere 11 elongate, about as long as antennomeres 9–10 combined. Labrum wider than long, with anterior margin sinuous; two short and closer to each other bristles on extreme anterior region at each side (d2- d1); right above, one very long bristle on each side (m1), next to lateral margin; one to two mid to long bristles on posterior region (p2-p1) (Fig. 3). Mandibles symmetrical, slim, toothless (Fig. 3B). Mentum fused to submentum (postmentum), subtrapezoidal, one long main bristle on each side of anterior region, each right in front of a medium sized one (Fig. 5). Prementum extremely reduced, labial palpi indistinct. Maxilla with galea subquadrate, lacina narrower, and palpi 4-jointed: first palpomere transverse, about four times shorter than second, which is elongate; third palpomere longer than wide, narrower at base; fourth palpomere reduced to less than half of length of filamentous sensillae (Fig. 3).

Thorax with considerable areas of exposed membrane between head and prothorax, and prothorax and mesometathorax (Figs. 1; 2). Pronotum slightly wider than long; prosternum with small area of sclerotization between legs, and other areas membranous. Mesothorax shorter than metathorax (Fig. 3). Scutellum suboval. Endosternite with base extended laterally by secondary sclerotization, where metalegs attach; between these extended nodules, no secondary sclerotization was seen; arms very long, thin and contiguous (Fig. 3). Elytron subtrapezoidal in shape, with proximal and distal margins oblique to elytron length, but more strongly tapering in distal-lateral region of elytron, leaving round apex; two long bristles vertically aligned on central region, another long bristle more proximal-lateral placed; and sparser shorter bristles across elytron surface (Figs. 3F and G). Hind wings presumably shed off, leaving only small stubs (Fig. 3). Legs developed, first tarsomere gradually increasing in length from pro to meso, and to hind legs (Fig. 1).

Abdomen strongly physogastric and modified, recurved at segment II, with apex anteriorly positioned, reaching the head (Fig. 1). Third segment modified into an egg-shaped region considerably longer than remaining segments, that follows a strong constriction separating it from remaining segments (Figs. 1, 4); segments VII–VIII swollen. Abdomen bearing tree pairs of pseudoappeandages: first pair, at pleural region of segment IV, contiguous, strongly swollen at their ends, bearing many short bristles; second pair, at pleural region of segment V, similar to first pair, except they are smaller and seemingly less sclerotized; third pair represented by strong sclerotized, gradually swollen towards apex, distally-directed contiguous pseudoappeandages, between segments VI and VIII, centrally disposed of (Figs. 1, 4). Tergite I represented by a thin sclerotized tergite, almost straight, attached to metanotum (Fig. 3). Tergite II straplike, with lateral secondary sclerotization fused to secondary sclerotization of sternite II, forming one complete ring (Fig. 2). Sternite II modified, with acute distally subtriangular secondary sclerotization process (Figs. 2A and B). Tergites III-V broader and more sclerotized than tergite II, mostly concealed by recurved abdomen. Sternite III modified in expanded shield-like structure on dorsal view (morphological ventral) of ovoid part of the abdomen (Figs. 1, 2, 4A). Sternite IV strap-like, with one notch in the middle, and secondary sclerotization separated by membranous area (Figs. 1, 4); sternite V strap-like, with one notch medially, and considerable area of secondary sclerotization, lateral and thinly distal to primary sclerotized piece (Figs. 1, 4,); sternite VI strap-like, with a great portion of distal secondary sclerotization displaying sinuous margin; pleural region of segment VI slightly inflated and with cluster of short bristles (Figs. 1a,b, 4a, d). Sternite VII with primary sclerotized area with proximal margin round, and distally disposed secondary sclerotization with one medial acute process (Figs. 1b, 4a, e). Tergite VIII with long apodemes and secondary sclerotization between them, forming overall one conspicuous plate; base subquadrate with one long main bristle on row A and one on row P, but all surface covered with midsized to rather long bristles (Figs. 3h, i). Sternite VIII subtrapezoidal, distal margin narrower than proximal; two pairs or long bristles horizontally arranged little below the halfline of piece (Fig. 3j). Tergites X and IX very compact together (Fig. 3K); tergite X subtriangular; sternite IX at least in female seems absent or completely fused to lateral margins of tergite IX. Spermatheca indistinct.

Host relationship. Two specimens were collected in a small (~ 20 cm) eroded mound nest, with Australitermes sp. (Figs. 6A and C) and Nasutitermes sp. (Figs. 6B and D).

Etymology. The specific name is dedicated to Dr. Tiago F. Carrijo, the termitologist and colleague who collected the specimens.

Type material. Holotype (#F). Australia: Northern Territory: Litchfield, Litchfield National Park, - 13.04759S, 130.9106E, 8-10/VII/2014, T. Carrijo col., with Australitermes sp. (MZUSP 23728), and Nasutitermes sp. (MZUSP 26578) beetle code MZSP 21193. Paratype (#F). 1, same data and collected along with the holotype.

Comparative remarks. Austrospirachtha carrijoi sp. nov. is similar in overall appearance to A. mimetes. However, there are several distinct differences between the two species. These include the shape of the abdomen, secondary sclerotization on sternites, shape of the last pseudoappendages (Fig. 4), and a less pronounced difference in the maxilla (with A. mimetes in parentheses): The first maxillary palpomere is distinct in A. carrijoi sp. nov. (Indistinct in A. mimetes, see Watson 1973, fig. 5); the modified, egg-like part of the abdomen is longer than the subsequent segments combined in A. carrijoi sp. nov. (Fig. 4A) (shorter in A. mimetes, Fig. 4F); sternite V in A. carrijoi sp. nov. has a thinly distal area of secondary sclerotization in addition to the lateral ones (Fig. 4C) (only lateral areas have secondary sclerotization in A. mimetes, Fig. 4H); sternite VI in A. carrijoi sp. nov. has a distal secondary sclerotization with a sinuous margin (Fig. 4D) (straight margin in A. mimetes, Fig. 4I); and sternite VII in A. carrijoi sp. nov. has a distally disposed secondary sclerotization with a medial acute process (Fig. 4E) (without acute process in A. mimetes, Fig. 4J).

Upon reading Watson’s (1973) work and examining and interpreting this new species, it is worth noting that there is some confusion regarding what constitutes sternite III. This confusion is understandable, as the modifications to the membranous area and secondary sclerotization can disrupt the typical morphology of these beetles. Our main disagreement with Watson pertains to the modified, inflated, egg-like part of the abdomen, where we consider the sclerotized plate to be a modification of sternite III, whereas Watson views it simply as secondary sclerotization of the intersegmental membrane (Figs. 1, 2, 4a, f). What Watson identifies as the true third sternite, we regard as part of segment IV, with its secondary sclerotization (Figs. 1b, 4a, b, f, g). We could not find evidence to support Watson’s claim, as there is no clear segmental delimitation between these two pieces, we consider it belong to segment IV. Furthermore, while it is not a strict rule, in Corotocini, secondary sclerotization usually arises from primary sclerotized pieces rather than membranes far from the main sclerites.

As for Watson’s observations, it is noteworthy that we also haven’t found the labial palpi, the labium being overall extremely reduced; but in Jacobson et al. (1986) the authors stated at least for A. mimetes that, even though it is small, the labial palpi is 3-articled.