Oxyopomyrmex nitidior Santschi, 1910

Sebastian Salata & Lech Borowiec, 2015, A taxonomic revision of the genus Oxyopomyrmex André, 1881 (Hymenoptera: Formicidae), Zootaxa 4025 (1), pp. 1-66 : 40-44

Oxyopomyrmex nitidior Santschi, 1910 stat. nov.

( Figs. 43, 44, 45, 46, 47, 48, 80, 81, 86, 87)

Oxyopomyrmex santschii var. nitidior Santschi, 1910: 46 (w.)

Oxyopomyrmex emeryi var. laticeps Santschi, 1915: 62 (w.) syn. nov.

Oxyopomyrmex emeryi st. sabulonis Santschi, 1915: 62 (w.); Santschi 1923: 326 (as good species); Collingwood 1985: 246; Collingwood 1996: 304 syn. nov.

Type locality: Kairouan, Tunisia .

Type material. Oxyopomyrmex santschii var. nitidior: lectotype worker (present designation): F. Santschi det. 1937 | Oxyopomyrmex | Santschii For. | v. nitidior Sants. || type || TUNISIE | Kairounan | Dr Santschi | 7.XI. 1909 || Sammlung | Dr. F. Santschi | Kairouan || ANTWEB | CASENT | 0 913250 ( NHMB) ; 1 paralectotype worker: F. Santschi det. 1937 | Oxyopomyrmex | Santschii For. | v. nitidior Sants. || type || TUNISIE | Kairounan | Dr Santschi | 7.XI. 1909 || Sammlung | Dr. F. Santschi | Kairouan || NHB-ONS ( NHMB) ; 4 paralectotype workers: the same data as lectotype ( NHMB) .

Oxyopomyrmex emeryi var. laticeps : 1 worker— Oxyopomyrmex | Emeryi Sants | v. laticeps Sants | SANTSCHI det. 1915 || Tunisie | Sousse | (Normand 1915) || type || Sammlung | Dr. F. Santschi | Kairouan || ANTWEB | CASENT | 0 913246 ( NHMB) .

Oxyopomyrmex emeryi st. sabulonis : 7 workers— Oxyopomyrmex | Emeryi Sants |st. sabulonis Sant | SANTSCHI det. 1914 || Tunisie | Garn et Fayat | 90 km O. Kef. | V 1913 Santschi || Tunisie | Gam et Fayat | Dr. F. Santschi || V 1913 || type || Sammlung | Dr. F. Santschi | Kairouan || ANTWEB | CASENT | 0 913245 ( NHMB) .

Other material examined. 6 workers— Oxyopomyrmex | Emeryi Sant. | st. sabulonis | Sants ( NHMB) ; 2 workers—Tunisie | Le Kef. | Dr. F. Santschi || Sammlung | Dr. F. Santschi | Kairouan ( NHMB) .

Gyne. Unknown.

Male. Unknown.

Worker. Redescription. Measurements (n= 19): HL: 0.679 ± 0.048 (0.592-0.749); HW: 0.685 ± 0.041 (0.603- 0.749); SL: 0.482 ± 0.028 (0.425-0.531); EL: 0.239 ± 0.015 (0.212-0.257); EW: 0.129 ± 0.008 (0.112-0.145); ML: 0.812 ± 0.056 (0.704-0.894); PSL: 0.174 ± 0.013 (0.156-0.201); SDL: 0.123 ± 0.01 (0.101-0.14); PL: 0.311 ± 0.028 (0.268-0.346); PPL: 0.221 ± 0.018 (0.201-0.246); PH: 0.237 ± 0.011 (0.223-0.257); PPH: 0.227 ± 0.007 (0.223-0.24); PNW: 0.434 ± 0.029 (0.385-0.48); TL: 0.474 ± 0.036 (0.413-0.525); TW: 0.105 ± 0.008 (0.089- 0.112); PW: 0.162 ± 0.019 (0.134-0.19); PPW: 0.247 ± 0.018 (0.212-0.268); HI: 100.9 ± 2.0 (96.9-103.5); SI 1: 71.1 ± 2.2 (67.0- 74.1); EI: 54.3 ± 3.9 (49.8-63.2); SI 2: 70.4 ± 1.7 (67.6-73.2); MI: 185.6 ± 5.1 (175.1-190.6); SPI: 142.4 ± 13.1 (111.4-163.4); PI 1: 133.9 ± 11.0 (114.0- 145.3); PI 2: 37.5 ± 3.6 (28.6-41.1); PPI 1: 99.7 ± 8.4 (90.1- 110.3); PPI 2: 56.5 ± 1.9 (53.1-60.3); HTI 1: 68.8 ± 2.3 (64.9-72.3); HTI 2: 22.1 ± 1.0 (20.8-24.5).

Head and thorax from brown to black. Abdomen darker than head and thorax or in the same colour Legs paler than thorax. Antennal scapes in the same colour as head, apex of the scapes and funiculus paler than head ( Figs. 43, 44, 45, 46, 47, 48).

Head posterior to eyes with straight lateral surfaces, deeply rounded on the posterior edges ( Figs. 45, 48). Anterior margin of the clypeus smooth and straight. Eyes longitudinal, strongly narrowing downward, reaching anteroventral margin of head, 0.4 times as long as length of the head. Scape short, 0.7 times as long as width of the head, at base 0.7 times as wide as in apex, gradually widened, slightly bent downward. Funiculus short, 1.58 times as long as scape, first segment elongate, triangular, 1.8 times as long as wide on apex, 2.75 times as long as second segment, length ratio of segments 100: 36: 32: 32: 36: 46: 46: 64: 109: 181, apical segments 1.8 times as wide as basal segments ( Figs. 44, 45). Surface of the scape with very fine microsculpture, shiny, covered with short and appressed setae.

Promesonotum 1.2 times as long as wide, gently convex or flat in profile. Promesonotal suture distinct, the border between dorsal and posterior surfaces of the promesonotum gently curved in profile view. Propodeum quadrate, 0.8 times as long as wide, propodeal spines short, triangular, rising obliquely upwards ( Figs. 44, 47). Petiole rounded with short peduncle, its anterior face straight, node flat on dorsal surface in profile. Posterior face slightly concave. Ventral margin of petiole straight and smooth ( Figs. 44, 47). Postpetiole regularly rounded in profile. Postpetiole 0.9 times as long as wide in dorsal view, regularly widened from base to top, apical half with gently rounded sides ( Figs. 44, 47).

Mandibles rounded, with outer and dorsal edges straight and smooth, inner margin with one large and 7-8 smaller teeth, the apical tooth massive and long. Clypeus smooth and shiny on entire surface. Frontal carinae short, extending to 1 / 3 length of eye; antennal fossa deeply impressed, shiny and microreticulate, frontal lobes with thin longitudinal striae and microreticulate, shiny ( Figs. 45, 48). Frons shiny, with longitudinal striae ( Fig. 45) or distinct reticulation to smooth on lateral surfaces ( Fig. 48). Center of frons always smooth and shiny or with striation sparser than in surrounding area and smooth surface between striation ( Figs. 86, 87). Area above eyes shiny with longitudinal striae and fine reticulation or smooth ( Figs. 45, 48). Ventral surface of the head with distinct striation and smooth at the posterior edge ( Fig. 45) or smooth and shiny with fine reticulation ( Fig. 48), gena smooth and shiny with fine microreticulation ( Figs. 44, 47). Entire head bearing setae, posterior margin with a few erect setae directed forward, lateral surfaces of the head with sparse appressed to semierect setae directed toward anterior margin, frontal area with sparse appressed to semierect setae placed transversely, directed to the center of the head, ventral surface of the head with a prominent psammophore and appressed to erect long setae. Pronotum shiny, rugose with striation, lateral surfaces shiny area between striation and rugosity always smooth. Dorsal suface of pronotum rugulose or with striation, central area usually with weaker sculpture ( Figs. 43, 46, 80, 81). Mesonotum on the dorsal surface rugose with parallel striation, lateral surfaces punctate with several longitudinal rugae on the upper edge, dorsal surface of propodeum with striation or rugose, surface between propodeal spines shiny with striation, below spiracles punctate with a few rugae in the posterior surface ( Figs. 43, 46, 80, 81). Dorsal suface of mesosoma with at least 3-5 setae on anterior half, mesonotum and anterior propodeum with several setae. Base of petiole and postpetiole on the entire surface punctate, nodes punctate, on the top with fine longitudinal rugae, without microsculpture, shiny, covered with several setae. Gaster shiny and smooth, bearing sparse, erect setae.

Legs short, hind femora 0.9 times as long as mesosoma length, hind tibia 0.6 times as long as hind femora, hind tarsi 1.3 times as long as hind femora. Dorsal surface of femora with short, sparse, semierect setae, inner margin with a row of the sparse,short setae, tibiae bearing short, semierect setae on the entire surface, inner margins with a row semierect setae ( Figs. 44, 47).

Biological data. Nests have been located in sandy soil ( Santschii 1910) and the nest entrance was always surrounded by a crater ( Santschii 1915). Workers have also been collected in dry pasture in highland alluvial valleys ( Collingwood 1985).

Distribution. Algeria, Egypt, Saudi Arabia, Tunisia.

Differential diagnosis. Oxyopomyrmex nitidior can be easily distinguished from other species by the presence of smooth and shiny sculpture on the center of the frons. In specimens with strong striation overall, this area can be covered by sparser/weaker striae as compared to the rest of the head. Additionally, in these specimens the area between striae is shiny and smooth rather than rugose. Specimens of O. nitidior with limited striation at the head, can be distinguished from other species belonging to this group by the following features: from O. emeryi it differs in the lack of punctation on the dorsal and lateral surfaces of the pronotum; from O. insularis it can be distinguished by the presence of distinct rugosity and striae on the entire surface of the promesonotum; from O. oculatus it differs by lacking distinct punctation on the top and edges of the promesonotum. Specimens of O. nitidior that have striae covering the entire surface of the head can be distinguished from O. negevensis , O. polybotesi and O. pygmalioni by lacking punctation on the dorsal durface of the pronotum and by having the genae devoid of striation and rugosity; from O. saulcyi and O. nigripes it differs by lacking longitudinal striae on the genae and by weak rugosity on the dorsal and lateral surfaces of the promesonotum; from O. laevibus it differs by having paler colouration, a flat promesonotum (in profile view) and the presence of the rugosity on dorsal and lateral surfaces of the promesonotum.

Comments. Oxyopomyrmex nitidior is characterized by high variability of striation on the face. Both specimens with longitudinal striae limited to the frons and specimens with the entire face covered by a distinct striation occur in the same series of type specimens. The only common feature of all the specimens is the structure of the center of the frons (see differential diagnosis above). In the type series of Oxyopomyrmex santschii var. nitidior Santschi, 1910 , O. emeryi var. laticeps Santschi, 1915 and O. emeryi st. sabulonis Santschi, 1915 we found specimens with variable levels of striation covering the head and variable sculpturation on the dorsal surface of the pronotum. In each of the type series of these three taxa we found specimens which have the same type of sculpture and striation on the head and thorax. The differences between O. nitidior and O. sabulonis noted by Santschi (1915), are insignificant when we take the intraspecific variability of these features into account. Moreover, we didn’t find any significant differences in the measurements and indices between type series of all taxa mentioned above. All these features enabled us to synonymize O. emeryi var. laticeps and O. emeryi st. sabulonis with O. nitidior .