Strumigenys zemi

One of two endemic Strumigenys species found on the Caribbean island of Hispaniola.

Identification
Booher et al. (2019) – A member of the nitens group. Strumigenys zemi can be distinguished from other Strumigenys in the group by two characters, a dental count of seven and enlarged occipital lobes. The latter helps form the distinctive sub-cordate head shape, when seen in full face view, of S. zemi. This species can also be distinguished from Strumigenys convexiceps by differences in the basigastral costulae. These extend only to the very anteriormost part of the first gastral tergite in S. zemi, while they extend beyond the basalmost quarter of the tergite in S. convexiceps. Additional characters that can be used to separate S. zemi from Strumigenys caiman and Strumigenys nitens are the comparatively broad petiolar node in dorsal view, which is approximately 2/3 of the width of the postpetiole (roughly 1/2 in S. caiman and S. nitens), the lack of spatulate setae anywhere on the body, as well as the short mandibles (MI 28-32 vs. 31-39 in S. caiman and S. nitens), short antennal scapes (SI 46-54 vs. 56-74), and compact mesosoma (WL approximately 1.8 times PW vs. 2.0-2.3).

Distribution based on Regional Taxon Lists
Neotropical Region: Dominican Republic.

Biology
Booher et al. (2019) – Discovered in mature forests of the Dominican Republic. The two localities where S. zemi has been collected are from an area of the Cordillera Septentrional near the northern coast. The type locality is lowland mature secondary broadleaf moist forest in the Toro Palomo sector of Loma Guaconejo Scientific Reserve. The holotype worker, a dealate gyne, and several paratype workers were collected in winkler samples (sifted leaf-litter) from two areas about a kilometer apart. Additional specimens were found in a mid-elevation broadleaf moist forest at the summit of Loma Quita Espuela. This is the highest peak (985m) of the Cordillera Septentrional, and the collection site is within a scientific reserve that bears the mountain's name. The hand-collected specimens, two workers and brood, were discovered under a moss mat that was covering a small boulder.

Nomenclature

 *  zemi. Strumigenys zemi Booher, Prebus & Lubertazzi, 2019: 348, figs. 7, 8 (w.) DOMINICAN REPUBLIC.

Description
Holotype HL = 0.43; HW = 0.38; ML = 0.13; PW =0.27; SL = 0.18; TL = 1.83; WL = 0.48; CI = 89; MI = 30; SI = 48. Paratype (n=2) HL = 0.41-42 (0.42); HW = 0.36-0.36 (0.36); ML = 0.13-0.13 (0.13); PW = 0.25-0.26 (0.26); SL = 0.19-0.20 (0.20); TL = 1.71-1.73 (1.72); WL = 0.44-0.46 (0.45); CI = 87-89 (88); MI = 30-32 (31); SI = 52-54 (53). Non-types (n=4) HL = 0.39-0.45 (0.42); HW = 0.33-0.4 (0.37); ML = 0.12-0.13 (0.13); PW = 0.25-0.27 (0.26); SL = 0.18-0.19 (0.18); FL = 0.23-0.23 (0.23); CT = 0.29-0.29 (0.29); EL = 0.04-0.05 (0.05); TL = 1.73-1.83 (1.79); WL = 0.45-0.49 (0.47); CI = 84-90 (87); MI = 28-33 (30); SI = 46-53 (50)

Mandibles in full face view and at full closure triangular and tapering apically; MI 28-33 Inner mandibular margin with a series three evenly spaced teeth, incrementally increasing in length distally, with the apices of the basal two teeth failing to meet when the mandibles are fully closed. Apices of mandibles with four teeth arranged vertically: the upper two long and spiniform, and the lower two shorter and triangular, giving a total dental count of seven. Antennal scapes short: SI 46-54. Occipital lobes enlarged, with the lateral margins of the head converging anteriorly and the posterior margin broadly concave in full-face view. Clypeus smooth and shining. Cephalic dorsum with a smooth and shining central strip that is flanked by finely punctate-striolate sculpture, which extends from the border of the clypeus and frontal carinae nearly to the apex of the occipital lobes. Dorsum of head with elongate, fine, tapering setae which curve toward the midline. Compound eye small: diameter less than the maximum width of the antennal scape. In profile view, head with dense punctate sculpture that extends from the apex of the antennal scrobe to postbuccal impression, and uniformly covers the ventral surface of the head capsule.

Mesosoma compact: WL approximately 1.8 times PW. Uniformly smooth and shining except for faint punctae around the propodeal spiracle and lamellae. Dorsal surface with sparse elongate, fine, tapering setae which curve toward the midline.

Petiolar node broad, roughly 2/3 as broad as postpetiole in dorsal view. Petiolar peduncle covered in dense reticulate sculpture, but dorsal surface of petiole and postpetiole smooth and shining. Dorsal surfaces of petiole and postpetiole with long, fine, tapering setae which curve toward the midline. Basigastral costulae present only on the limbus and the extreme base of the first gastral tergite, the remainder of which is smooth and shining. First gastral tergite with numerous long, fine, tapering setae.

Head, mesosoma, and gaster uniformly dark brown. Appendages light brown.

Etymology
In the theology of the Caribbean Taíno people who occupied pre-Colombian Hispaniola, “zemis” were ancestral spirits, typically housed in sculptural objects. By the account of Christopher Columbus’s ethnographer, Fray Ramón Pané, sculptural zemis were buried in Taíno manioc gardens to aid soil fertility. Often these were in the shape of an isosceles triangle, somewhat reminiscent of the head of S. zemi in full-face view. The name is a noun in apposition.

References based on Global Ant Biodiversity Informatics

 * Booher D. B., M. M. Prebus, and D. Lubertazzi. 2019. A taxonomic revision of the Strumigenys nitens and simulans groups (Hymenoptera: Formicidae), two Caribbean radiations of leaf litter ants. Zootaxa 4656: 335-358.