Nesomyrmex micheleae, a new ant species (Hymenoptera: Formicidae) from the Dhofar Governorate, Oman, with a synoptic list, distribution map and key to the Arabian Nesomyrmex Author Sharaf, Mostafa R. Author Mohamed, Amr A. Author Al Dhafer, Hathal M. Author Aldawood, Abdulrahman S. text Journal of Natural History 2020 2020-07-27 54 5 - 6 351 365 http://dx.doi.org/10.1080/00222933.2020.1762013 journal article 10.1080/00222933.2020.1762013 1464-5262 Nesomyrmex micheleae Sharaf sp. nov. urn:lsid:zoobank.org:act: 1D2EC498-3B2E-43CD-A3C0-1C6C237471E2 ( Figure 4a – c ) Holotype worker : OMAN : DHOFAR : Ayn Sahlanoot , 17.14766°N , 54.17878°E , alt. 151 m , 16 November 2017 , BS, M. R . Sharaf leg., King Saud University Museum of Arthropods , Plant Protection Department , College of Food and Agriculture Sciences , King Saud University , Riyadh , Kingdom of Saudi Arabia ( KSMA ). Paratype workers : Same data as the holotype, 2 w, CASENT0922872 ( KSMA ) . Measurements Holotype worker : HL 0.75; HW 0.67; SL 0.62; EL 0.20; PRH 0.37; PRW 0.40; WL 1.0; PSL 0.07; PTL 0.25; PTH 0.27; PTW 0.25; PPL 0.17; PPH 0.25; PPW 0.30; TL 3.25; OI 30; SI 93; CI 89; DMI 40 ; LMI 37 ; PSLI 9 ; LPeI 93 ; DPeI 100 ; LPpI 68 ; DPpI 176 ; PPI 120 . Paratype workers : HL 0.77 – 0.82; HW 0.60 – 0.66; SL 0.53 – 0.62; EL 0.15 – 0.17; PRH 0.25 – 0.37; PRW 0.44 – 0.45; WL 0.97 – 0.98; PSL 0.05 – 0.06; PTL 0.17 – 0.21; PTH 0.20 – 0.22; PTW 0.20 – 0.23; PPL 0.17 – 0.18; PPH 0.21 – 0.22; PPW 0.27 – 0.28; TL 3.12 – 3.22; OI 23 – 28; SI 80 – 103; CI 78 – 80; DMI 45 – 46; LMI 26 – 38; OI 23 – 30, PSLI 6 – 7; LPeI 85 – 95; DPeI 110 – 118; LPpI 77 – 86; DPpI 156 – 159; PPI 122 – 135 ( n = 2). Figure 2. Key illustrations: (a) clypeus of Nesomyrmex humerosus , CASENT 0904729 (Alexandra Westrich); (b) mesosoma of N. humerosus in dorsal view, CASENT0904729 (Alexandra Westrich); (c) mesosoma of N. humerosus in profile, CASENT0904729 (Alexandra Westrich); (d) clypeus of N. angulatus , CASENT 0906378 (Estella Ortega); (e) mesosoma of N. angulatus in dorsal view, CASENT0906378 (Estella Ortega); (f) mesosoma of N. angulatus in profile, CASENT0906378 (Estella Ortega), https://www.antweb.org/citing_antweb.jsp. Figure 3. Key illustrations: (a) clypeus of N. zaheri , CASENT 0906379 (Estella Ortega); (b) clypeus of N. angulatus , CASENT 0922010 (Zach Lieberman); (c) body of N. angulatus in profile, CASENT0922010 (Zach Lieberman); (d) head of N. micheleae sp. nov. in full-face view, CASENT0922872 (Michele Esposito), https://www.antweb.org/citing_antweb.jsp. Diagnosis. Nesomyrmex micheleae sp. nov. can be distinguished from regional congeners by the combination of the following characters: median clypeal carina distinct; petiolar node nearly hexagonal in dorsal view; area in front of eyes and median cephalic surface irregularly, longitudinally rugulose; body covered with erect, blunt, stout and moderately short setae; bicoloured species with head black-brown, mesosoma, petiole, postpetiole and appendages brown, gaster golden yellow. Description Worker. Head. Head distinctly longer than broad (CI 78 – 89) with straight or feebly convex posterior margin and lateral sides, broader posteriorly behind eye level in fullface view; lateral sides of head making a feeble but distinct obtuse angle with posterior margin of head in full-face view; antennal scapes relatively short (SI 80 – 103), when laid back from insertions fail to reach posterior margin of head in full-face view; masticatory margin of mandible with five teeth, decreasing in size from largest, acute apical tooth to smallest basal denticle; eyes of moderate size (OI 23 – 30) located at mid-length of head; anterior clypeal margin rounded; median clypeal carina distinct; frontal carinae and antennal scrobes absent. Mesosoma. In profile mesosomal outline absolutely flat without promesonotal suture or metanotal groove; pronotal corners acutely angular in dorsal view; propodeum armed with short and acute propodeal teeth (PSLI 6 – 9); metapleural lobe low and rounded. Petiole. In profile, petiolar peduncle short; node relatively high (LPeI 85 – 95) with straight-sloping anterior face; petiolar node nearly hexagonal in dorsal view and almost as broad as or little broader than long (DPeI 100 – 118); anteroventral process triangular and blunt. Postpetiole. Distinctly broader than long in dorsal view (PPI 122 – 135) with node lower than petiolar node in profile; postpetiole globular in profile distinctly higher than long (LPpI 68 – 86); in dorsal view, postpetiolar node more than 1.5× broader than long (DPpI 156 – 176); in dorsal view, postpetiolar node distinctly broader than petiolar node (PPI 120 – 135). Sculpture. Mandibles longitudinally striated; area in front of eyes and median cephalic surface irregularly longitudinally rugulose; ground sculpture between cephalic rugae and remaining cephalic surface finely and superficially imbricate; median clypeal carina distinct, two lateral feebly distinct longitudinal rugae present; mesosomal, petiolar and postpetiolar sides finely reticulatepunctate; seen from dorsal view, mesosomal margins, petiolar and postpetiolar nodes distinctly reticulate-rugulose; mesonotum and propodeal dorsum finely punctate; gaster smooth and shining. Pilosity. Head, mesosoma, petiole, postpetiole and gaster dorsally with erect, blunt, stout and moderately short setae; funiculus with dense appressed pubescence; anterior clypeal margin with fine long setae; mandibles with fine shorter setae. Colour. Strongly bicoloured species with head black-brown, mesosoma, petiole, postpetiole, antennae, femur and tibia brown or dark brown, tarsi yellow, gaster golden yellow, with brown tints dorsally on first gastral tergite. Figure 4. Nesomyrmex micheleae , sp. nov. , paratype worker: (a) body in profile; (b) body in dorsal view; (c) head in full-face view, CASENT0922872 (Michele Esposito), https://www.antweb.org/citing_ antweb.jsp. Etymology. The patronym for N . micheleae sp. nov. has been chosen in honour of Michele Esposito, California Academy of Sciences (CAS), San Francisco. Differential diagnosis. As defined by Hita Garcia et al. (2017) , N. micheleae sp. nov. is a member of the N. angulatus species group with which it shares the following characters: antennae 12-segmented; anterior clypeal margin convex and without anterior projections; propodeal spines well developed; petiole and postpetiole without lateral projections; body pilosity short and blunt. Within the N. angulatus species group, N. grisoni (Forel 1916) from Democratic Republic of Congo is apparently morphologically similar to N. micheleae sp. nov. , sharing the sharply angular pronotal corners, the distinctly reticulate-rugulose petiolar and postpetiolar nodes, the smooth gaster, the short and acute propodeal spines, the short petiolar peduncle, and the blunt and short body pilosity. However, N. micheleae sp. nov. is readily distinguished from N. grisoni by the golden yellow gaster that contrasts with the dark brown body; the irregular longitudinal rugulose sculpture on cephalic surface; the finely punctate mesonotum and propodeal dorsum. Nesomyrmex grisoni has a unicolourous brown or black-brown body, and strong reticulate rugae on cephalic, mesonotal and propodeal surfaces. Among the Arabian species, N. micheleae sp. nov. appears superficially similar to N. zaheri but the former species can be separated by the relatively longer scapes that fail to reach the posterior margin of the head in full-face view, and the obtusely angled pronotal corners when seen in dorsal view, whereas N . zaheri has distinctly shorter scapes that surpass the posterior level of the eyes by about the length of the first funicular segment in full-face view, and distinctly rounded pronotal corners. Nesomyrmex micheleae sp. nov. also looks similar to N. angulatus but the latter species has relatively longer scapes that reach the posterior margin of head in full-face view, one pair of small acute dents on pronotal corners when seen in dorsal view, and higher ocular and dorsal postpetiole indices (OI 27 – 35, DPpI 154 – 188) versus (OI 23 – 28; DPpI 156 – 159) in N . micheleae . Additionally, N. micheleae sp. nov. is easily separated from all Arabian Nesomyrmex species by its strongly bicoloured body which has a black to black-brown head, and the mesosoma, petiole and postpetiole are dark brown, contrasting with the golden yellow gaster. Ecological and biological notes. The three collected workers of N . micheleae sp. nov. were foraging on a large tree in Ayn Sahalnoot of the Dhofar Governorate in the south of Oman ( Figure 5 ), and were collected using a beating sheet . Additional collections in a broad range of habitats in the Dhofar Governorate were not successful in obtaining additional material . The type locality, Ayn Sahalnoot or Wadi Sahalnoot , has spectacular natural scenery . The Dhofar Governorate is a rich, biodiverse region shaped by climate factors (the average annual temperature and precipitation in Salalah are 25.8°C and> 94 mm , respectively) and vegetated with frequent areas of small- to medium-sized perennial shrubs, scattered between broader areas of loam, gravel and rocks and semi-evergreen grassland . Geographic range. Known only from Oman .