Perissomyrmex emarginatus, Ogata, K. & Okido, H., 2007

Ogata, K. & Okido, H., 2007, Revision of the ant genus Perissomyrmex with notes on the phylogeny of the tribe Myrmecinini., Advances in ant systematics (Hymenoptera: Formicidae): Homage to E. O. Wilson - 50 years of contributions. (Memoirs of the American Entomological Institute 80), pp. 352-369 : 359-360

Perissomyrmex emarginatus new species

DESCRIPTION

Worker: Holotype measurements (mm): TL 3.73, HL 0.86, HW 0.90 ,, SL 0.78, EL 0.10, PW 0.57, ML 0.98, GL 1.07, GW 0.86. Indices: CI 104.65, SI 86.67.

Paratype measurements (4 workers, 3 measured): TL 3.97 - 4.14, HL 0.86 - 0.96, HW 0.92 - 0.94, SL 0.74 - 0.78, PW 0.57 - 0.59, ML 0.90 - 1.11, GL 1.07 - 1.39, GW 0.86 - 0.90). Indices: CI 95.74 - 106.98, SI 82.22 - 86.67.

Head subrectangular, with slightly concave posterior border and rounded posterior corners; sides slightly diverging anteriorly. Eyes situated in the midlength of sides, comprising 15 - 18 ommatidia. Anterior margin of clypeus with four teeth; median paired teeth large and distinct, lateral paired teeth smaller and lower; the median paired ones separated by median notch, the lateral tooth located just in front of antennal insertion, and the median and lateral ones closely situated each other, sometimes fused at the base in each side; median notch distinct and deep, inverted U-shape, the bottom of notch reaching or exceeding level of anterior margin of lateral edge in front of antennal insertion. Frontal lobes almost reduced, frontal carina low, diverging posteriorly, reaching the level of eyes. Antennal toruli exposed, antennal insertion forming deep hollow forming distinct anterior edge. Mandible elongate with long basal margin and short masticatory margin; basal margin with one small but distinct tooth in the midlength; masticatory margin equipped with one apical and one subapical teeth followed by a diastema and one basal tooth. Antennae 9 segmented, scape exceeding posterior corner of head by its width; apical three segments forming club but obscure. Labrum with transverse preapical ridge; two small projections present on the dorsal surface in the middle.

Promesonotum raised, but the dorsal surface somewhat depressed; promesonotal suture weakly impressed. Anteroventral free margin of mesopleuron carinated but not forming expansion covering procoxa. Metanotal groove complete, deeply impressed. Dorsal outline of propodeum slightly raised. Spiracle circular and large, situated on lateral surface of propodeum in the middle. Propodeal spine straight, long and acute, directed backward and upward. Propodeal lobe low and rounded.

Petiole with anterior declivity, rounded tip and posterior face; ventral margin weakly sinuate but no subpetiolar process; anterior peduncle with distinct paired lateral projections in dorsal view, situated anterodorsal to the spiracle in lateral view. Postpetiole, in profile, with raised dorsal outline, anterior face convex, posterior face nearly vertical and in frontal view the crest rounded but pointed. Ventral margin to 1 st gastral segment not sinuate.

Head, mandible and mesosoma costate, lower part of mesopleuron and posterior part of propodeal spiracle unsculptured. Petiole mostly unsculptured. Anterior face of postpetiole smooth and shining, the rest finely punctate. Body dark yellowish brown, the appendages lighter.

Queen. TL 4.63 - 4.92, HL 1.07 - 1.19, HW 1.11 - 1.23, CI 103.36 - 110.81, SL 0.78 - 0.90, SI 68.91 - 73.17, PW 0.82 - 0.90, ML 1.31 - 1.39, GL 1.35 - 1.48, GW 1.11 - 1.19 (5 measured).

Similar to the worker, but the head wider than long with three ocelli. The dentition on mandibles and anterior clypeal margin basically same as in worker but tending to be worn down, so that the teeth are often low and obscure; the median portion of anterior clypeal margin produced with less distinct median notch and four teeth which are sometimes fused together. Mesosoma robust short and high, mesonotum thick, mesoscutellum overhanging metanotum, metanotum more of less convex in profile, propodeal spine robust directed backward. Petiole basically as in worker, but the ventral surface with distinct paired longitudinal keel originated from posterior end of the petiole running anteriorly and convergent at anterior 1 / 4 of petiole, lateral surface with longitudinal ridge from the portion above the spiracle to posterior end, and lateral projection more distinct. Apex of postpetiolar node pointed. Sculpture more distinct than that of worker. Coloration same as worker.

TYPE MATERIAL

Holotype, Worker, Lianwangpo, Mt. Emeishan, Emeishan Shi, Sichuan Prov., CHINA, 2310 m alt., 4. x. 1996 (S. Nomura & Zhao) (KU No. 3149). Paratypes (All from CHINA): 4 workers, 2 queens, same as holotype; 2 queens, Mt. Jiudingshan, Chapingshan Mts., Mao Xian, Sichuan Prov., 3670 m alt., 22. ix. 1996 (S. Nomura & Zhao); 1 queen, Leidongping, Mt. Emeishan, Emeishan Shi, Sichuan Prov., 2310 - 2350 m alt., 4. x. 1996 (S. Nomura & Zhao).

Remarks

All the material was collected by Berlese funnel. Collecting site of Mt Emeishan is a road side of mixed coniferous forest, Dabei site is more like evergreen forest, and Mt Jiudingshan site is somewhat shrubby. The altitudinal range of collecting sites is from 2300 m to 3700 m elevation. The lateral projections of the petiolar peduncle are sometimes asymmetrically developed.

In the worker caste, P. emarginatus is distinguished from two other Asian species in having the deeper median notch on the anterior clypeal margin. The bottom of the notch reaches or even exceeds the level of anterior ridges in front of antennal insertions. The body of P. emarginatus has more sculptured surface and the color is more brownish than the two other Asian species. The propodeal spines, if they are fully developed, are also different from those of P. monticola and P. nepalensis , being straight without upper curve. In the queen the median notch is shallower than that of the nonspecific workers, so that the depth and the shape cannot be used in separating species. Although we did not observe the queen of P. nepalensis , the dentition of the anterior clypeal margin is still useful; the 4 teeth are arranged closer together forming a blunt median projection in P. emarginatus , while the lateral paired teeth are small and separate from the median pair in P. monticola .