Rogeria tsumani, LaPolla & Sosa-Calvo, 2006

LaPolla, J. S. & Sosa-Calvo, J., 2006, Review of the ant genus Rogeria (Hymenoptera: Formicidae) in Guyana., Zootaxa 1330, pp. 59-68 : 59

Rogeria tsumani , NEW SPECIES

Holotype worker, GUYANA: Oronoque River just above juncture with New River , 29 July 1936 [coordinates determined by JSL: 2° 45'00" N 57° 26'00" W], coll. N.A. Weber. Paratype worker same locality as holotype. Holotype in USNM, paratype in MCZC.

Diagnosis (worker): mesosoma smooth and shiny, with scattered short appressed hairs; propodeal spines long, slightly inclined posterad; petiole pedunculate and with a distinct node, convex in lateral view.

Description (worker). Head: subquadrate in dorsal view; dorsolateral surface of head with widely spaced punctures, smooth and shiny in between; dorsomedian surface of head weakly longitudinally carinulate; nuchal grooves very shallow, not visible in lateral view; mandibles triangular; inner margin with 5 teeth, apical tooth largest; clypeal apron with shallow median depression. Mesosoma: promesonotum faintly longitudinally carinulate; promesonotal suture weakly marked; mesopleural suture incomplete; anepisternum and metapleuron weakly rugose; katepisternum smooth and shiny; dorsum of propodeum transversely rugose; propodeal spines long (SpL= 0.20-0.22) and slightly inclined posterad. Metasoma: petiole pedunculate, weakly rugulose, becoming smooth ventrally; petiolar ventral process smooth and shiny with a short anterior keel; postpetiole node tall, smooth and shiny; postpetiolar ventral margin rugose, with a short anterior keel. Body with scattered short, appressed hairs. Overall body color reddish-dark brown, with propodeum darker brown, and light brown legs. Queen and male unknown. Measurement: holotype and paratype (N= 2): TL= 3.75-3.88, HL= 0.86-0.88, HW= 0.69-0.72, ML= 0.39-0.41, SL= 0.52-0.55, EL= 0.12-0.15, PW= 0.55-0.55, WL= 0.95-0.97, SpL= 0.20-0.22, PL= 0.44-0.48, FLW= 0.23-0.25, PPL= 0.22-0.23, GL= 0.89-0.89, CI= 80-82, OI= 17-22, SI= 60-76, PSI= 21-23.

Etymology: Named in honor of Dr. Ted Suman, Research Associate at the National Museum of Natural History. Without Ted's hard work and dedication to the Guyana Ant Project much of the research being conducted on the Guyana ant fauna would not be possible.

Natural history: The two known specimens of R. tsumani were collected from a rotten branch that fell off a tree from about 30 meters height as Weber was walking through the forest (N.A. Weber, field notes, in MCZC archives). Weber reported looking through the rotting branch for the Rogeria nest, but he could not locate it. Rogeria tsumani is probably a canopy-dwelling species. While many Rogeria species are thought to nest in leaf litter and rotting wood on the ground, there is evidence that several species are arboreal or at least partly arboreal. Two species, R. blanda and R. tonduzi , have been taken from the trunks of cacao trees ( Kugler 1994), and Longino reported R. blanda nesting in a standing dead tree trunk from La Selva, Costa Rica (Longino, 19 August 2005, http:// www.evergreen.edu/ants/genera/Rogeria/SPECIES/blanda/blanda.html). The trunk was small and broken off at the top, with very soft rotten wood. In addition, R. belti , R. foreli , R. scandens , and R. terescandens may possess arboreal habits.

Comments: Only four species of Rogeria are known in which the mesosomal dorsum bears only appressed hairs: R. bruchi , R. foreli , R. prominula , and R. tsumani . Both R. bruchi and R. foreli possess a much more erect and distinct petiolar node compared to R. tsumani , and the propodeal spines of R. bruchi and R. foreli are at roughly right angles to the longitudinal axis of the mesosoma. In R. tsumani , in contrast, the propodeal spines are roughly parallel to the longitudinal axis of the mesosoma. Rogeria prominula has a unique propodeal shape (fig. 20) and a rugoreticulate head and mesosoma. In Kugler's (1994) key, R. tsumani would key to R. bruchi . Rogeria tsumani is a larger species (TL 3.7-3.9 in R. tsumani vs. 2.2-2.6 in R. bruchi ) with smaller eyes and darker brown coloration. Kugler (1994) constructed six informal species-groups. While he placed the majority of species into these species-groups, there was still a substantial number that he could not reliably place. Rogeria tsumani similarly fails to fall neatly into a species group.