Tetramorium tsingy, Garcia & Fisher, 2012

Garcia, Francisco Hita & Fisher, Brian L., 2012, The ant genus Tetramorium Mayr (Hymenoptera: Formicidae) in the Malagasy region — taxonomy of the T. bessonii, T. bonibony, T. dysalum, T. marginatum, T. tsingy, and T. weitzeckeri species groups, Zootaxa 3365, pp. 1-123 : 113-115

Tetramorium tsingy sp. n.

( Figs 157 , 158, 159, 160 )

Holotype worker, MADAGASCAR, Mahajanga, Parc National Tsingy de Bemaraha, 2.5 km 62° ENE Bekopaka, Ankidrodroa River , 19.13222 S, 44.81467 E, 100 m, tropical dry forest on tsingy, ground nest, BLF04392, 11.– 15.XI.2001 (B.L. Fisher, C. Griswold et al.) ( CASC: CASENT0426807 ). One paratype worker with same data as holotype ( CASC: CASENT0247113 ).

Diagnosis

Tetramorium tsingy is easily identifiable within its species group due to its strongly appressed pubescence on the first gastral tergite and the moderately short propodeal spines.

Description

HL 0.63–0.66; HW 0.60–0.62; SL 0.43–0.44; EL 0.14; PH 0.33–0.34; PW 0.42; WL 0.76; PSL 0.11; PTL 0.16; PTH 0.24; PTW 0.15; PPL 0.21; PPH 0.24; PPW 0.22–0.23; CI 95; SI 71–72; OI 23; DMI 55–56; LMI 43–45; PSLI 17; PeNI 35–36; LPeI 65–67; DPeI 94; PpNI 52–55; LPpI 88; DPpI 105–110; PPI 152–153 (two measured). Head weakly longer than wide (CI 95). Anterior clypeal margin with distinct median impression. Frontal carinae weakly developed and very fine, becoming weaker at anterior eye level, and fading out between posterior eye margin and posterior head margin. Antennal scrobes absent. Antennal scapes short, not reaching posterior head margin (SI 71–72). Eyes comparatively small to moderate (OI 23). Mesosomal outline in profile flat, weakly marginate from lateral to dorsal mesosoma, promesonotal suture and metanotal groove absent; mesosoma comparatively stout (LMI 43–45). Propodeum armed with short, triangular spines (PSLI 17). Propodeal lobes welldeveloped and broadly triangular, approximately of same height and volume as propodeal spines. Petiolar node in profile rectangular nodiform, approximately 1.3 times higher than long (LPeI 65–67), anterior and posterior faces approximately parallel, anterodorsal and posterodorsal angles at about same height, dorsum not tapering backwards posteriorly; node in dorsal view weakly but distinctly longer than wide (DPeI 94). Postpetiole in profile rounded and approximately 1.2 times higher than long (LPpI 88), in dorsal view weakly wider than long (DPpI 105–110). Postpetiole in profile more voluminous than petiolar node, in dorsal view approximately 1.5 times wider than petiolar node (PPI 152–153). Mandibles partly with superficial, weak striation, mostly unsculptured, and general appearance smooth and shiny; clypeus with strong median longitudinal ruga and one or two very weak rugulae at each side; cephalic dorsum between frontal carinae with a pair of weakly developed, longitudinal, median rugae, area between median rugae and frontal carinae almost unsculptured, few traces of rugulae present anteriorly, median rugae of shorter than frontal carinae and ending at eye level; lateral head mostly unsculptured with weak irregular longitudinal rugulae anteriorly. Mesosoma laterally with few irregular rugae or rugulae, remainder unsculptured, mesosomal dorsum generally unsculptured with few traces of rugulae only; petiole, postpetiole, and gaster unsculptured, smooth and shining. Ground sculpture on whole body faint to absent. All dorsal surfaces of head, mesosoma, and waist segments with short, fine subdecumbent to erect pilosity, first gastral tergite with short, strongly appressed pubescence. Body uniformly brown.

Notes

The new species is only known from the type locality, and only from two specimens, which is similar to the limited material known for T. tyrion . However, in contrast to the latter, more bionomic information is available for T. tsingy . The two specimens were sampled from a tropical dry forest on tsingy, and, interestingly, found in a ground nest of Aphaenogaster swammerdami Forel. Unfortunately , no additional information exists about the relationship between these two species. Nevertheless, A. swammerdami is a much larger species compared to T. tsingy . Also, A. swammerdami is a very common and abundant species known to have an omnivorous diet consisting of arthropods and seeds (Boehing-Gaese et al., 1996, 1999; Fisher, 2003). Fisher (2003) also reported that the nests of A. swammerdami are famous for being shared with snakes ( Leioheterodon modestus Günther ). The large nests of A. swammerdami appear to provide a variety of resources which could be used by T. tsingy . It could be that A. swammerdami ignores or tolerates the much smaller T. tsingy although this is highly speculative at the moment. However, a lifestyle carried out within another ant colony could account for the scarcity of T. tsingy material sampled so far. Nevertheless, more material and especially more nest collections from A. swammerdami or other ants including T. tsingy are needed to come to any final conclusion about the lifestyle of the latter species.

Tetramorium tsingy is not likely to be confused with T. tyrion since both differ significantly in gastral pilosity/ pubescence and development of the propodeal spines/teeth. In T. tsingy one can observe moderately short spines and strongly appressed pubescence on the first gastral tergite, whereas T. tyrion has only minute propodeal teeth and short but erect pilosity.

Etymology

The epithet tsingy is taken from the Malagasy language, and means "where one cannot walk barefoot". It is used to describe the karstic, vertical limestone formations encountered in the region. The new species appears to be endemic to this spectacular tsingy habitat. The species epithet is a noun in apposition and thus invariant.

Material examined

MADAGASCAR: Mahajanga, Parc National Tsingy de Bemaraha, 2.5 km 62° ENE Bekopaka, Ankidrodroa River, 19.13222 S, 44.81467 E, 100 m, tropical dry forest on tsingy, 11.–15.XI.2001 (B.L. Fisher, C. Griswold et al.).

Figures

FIGURES 156 & 157. 156. Body of T.tyrion in profile showing the minute propodeal teeth and short, fine erect pilosity on the first gastral tergite—CASENT0249085 (Estella Ortega 2011). 157. Body of T. tsingy in profile showing the moderately short propodeal spines and short and strongly appressed pubescence on the first gastral tergite—CASENT0426807 (Shannon Hartman 2011).

FIGURES 158–160. T. tsingy, holotype—CASENT0426807 (Shannon Hartman 2011). 158. Body in profile. 159. Body in dorsal view. 160. Head in full-face view.