Paratrechina zanjensis

Very little is known about the natural history of P. zanjensis; the 23 specimens collected in the Mkuju River region of the Selous Game Reserve in Tanzania were all found in 48-hour pitfall trap samples (present in 8 of a total of 60 samples from two sites separated by about 1.3 km) while none were found in the 40 Winkler-extracted leaf litter samples collected during daytime along the same transects. The two Tanzanian sites in which P. zanjensis were found were representative of mature dry miombo woodland, while they appeared to be absent from both dry and moist closed canopy forest sites nearby. The Angola and Mozambique specimens were also collected in miombo woodlands; this, in combination with the absence of P. zanjensis from 15 forest sites surveyed by Peter Hawkes in the Eastern Arc Mountains and Coastal Forests of Tanzania, suggests that the species prefers open woodland rather than forest habitats.

Identification
LaPolla & Fisher (2014): Head and mesosoma light brown to yellow with slightly darker gaster; mesosoma and head densely rugorecticulate; mandible with 8 teeth, one tooth on basal margin, another on inner mandibular margin.

LaPolla et al (2013) - The worker of P. zanjensis can easily be separated from P. longicornis based on the presence of erect macrosetae on the scapes. There are several other notable differences between the two species. The propodeal dorsal face of P. zanjensis is more convex than is observed in P. longicornis. Similarly, the pronotum and to a lesser degree the mesonotum are more convex in P. zanjensis, being almost flat in P. longicornis. The metanotal area is also longer and more distinct in P. zanjensis, being more strongly separated from the mesonotum and propodeum. Paratrechina zanjensis has erect macrosetae that are dark rather than pale as in P. longicornis, the body is glossier, and largely lacks the opalescent sheen / iridescence that is characteristic of P. longicornis. Unfortunately, the male and queen for P. zanjensis remain unknown. Paratrechina zanjensis is superficially similar to Nylanderia silvula, but can readily be distinguished from this species by its mandibular dentition (5 teeth in Paratrechina, 6 in Nylanderia), larger eyes, longer limbs and less strongly domed propodeum.

Distribution based on Regional Taxon Lists
Afrotropical Region: Angola, Mozambique, United Republic of Tanzania.

Nomenclature

 *  zanjensis. Paratrechina zanjensis LaPolla, Hawkes & Fisher, 2013: 76, figs 4–6, 8, 9 (w.) TANZANIA.

Description
WORKER. Measurements in millimeters (n=18): TL: 2.6-3.2; HW: 0.50-0.59; HL: 0.68-0.77; EL: 0.19-0.23; SL: 1.07-1.24; PW: 0.41-0.5; WL: 0.94-1.20; PrFL: 0.78-0.91; GL: 0.92-1.30.

Indices: CI: 71-79; REL2: 37-44; SI: 198-220.

Overall coloration dark brown with lighter mandibles, antennae (especially funicular segments towards tips) and legs (especially trochanters of mid and hind legs, and distal portions of tibiae and tarsi); cuticle smooth, shining, and with very faint shagreenate sculpture, which is more obvious on head and gaster. Head narrow, distinctly longer than broad, with abundant dark, erect macrosetae; anterior clypeal margin with a shallow medial indentation; scapes with a dense layer of pubescence and scattered erect macrosetae (SSC = 17-29); eyes large and convex, extending beyond head lateral margin in full frontal view; posterior head margin with rounded posterolateral corners; three distinct ocelli present. Mesosoma with scattered dark erect macrosetae (PSC = 2-5; MSC = 2-3); in profile pronotum and mesonotum shallowly convex dorsally, presenting a uniform overall curvature through their junction; metanotal area distinct, about 1/3 the length of the mesonotum; dorsal face of propodeum rounded, with short declivitious face; anterior portion of dorsal face with thin layer of pubescence. Gaster with abundant erect dark macrosetae.

Etymology
The specific epithet is derived from the ancient Arabic name for the stretch of East African coast that encompasses parts of modern day Kenya, Mozambique, and Tanzania.

References based on Global Ant Biodiversity Informatics

 * La Polla J. S., and B. L. Fisher. 2014. Then there were five: a reexamination of the ant genus Paratrechina (Hymenoptera, Formicidae). Zookeys 422: 35-48.
 * LaPolla J. S., P. G. Hawkes, and J. N. Fisher. 2013. Taxonomic review of the ant genus Paratrechina, with a description of a new species from Africa. Journal of Hymenoptera Research 35: 7182. doi: 10.3897/JHR.35.5628