Yunodorylus sexspinus

Yunodorylus sexspinus constructs nest in the soil and forage in soil or under litter. A nest including 385 individuals was observed in a soil sample of seasonal rain forest. Another nest containing 20 individuals was found in a soil sample of deciduous monsoon forest. Other individuals were also collected in soil of mountain rain forest and warm deciduous broad-leaf forest. (Xu 2000)

Identification
Borowiec (2009) - This species can be distinguished from Yunodorylus eguchii by differences in color, sculpture and shape of subpetiolar process. See eguchii for more details.

Distribution
China: Yunnan Province (Mengla County, Menghai County, Jinghong County). Altitude: 730-1,280m.

Distribution based on Regional Taxon Lists
Oriental Region: Thailand. Palaearctic Region: China.

Nomenclature

 *  sexspinus. Yunodorylus sexspinus Xu, 2000b: 298, figs. 1-6 (w.) CHINA.
 * Combination in Cerapachys: Bolton, 2003: 269.
 * Combination in Yunodorylus: Borowiec, M.L. 2016: 237.
 * Status as species: Borowiec, M.L. 2009: 53 (redescription); Chen, Shi & Zhou, 2016: 9 (in key).

Worker
Holotype worker: TL 3.4, HL 0.77, HW 0.70, CI 91, SL 0.37, SI 52, PW 0.50, AL 0.93, ML 0.40, PL 0.27, PH 0.40, DPW 0.37, LPI 150, DPI 138. Head nearly square, slightly longer than broad, narrowered anteriorly. In full face view, occiput shallowly depressed, occipital corners roundly prominent, lateral sides evenly convex. Anterior portion of gena convex. Mandibles elongate triangular, the large apical tooth followed by a smaller preapical tooth and 4 minute denticles. Clypeus reduced and only visible on lateral sides. Frontal lobes suberect and reached to anterior margin of head. Antennae with 12 segments, apex of scape reached to 7/15 of the distance from antennal socket to occipital corner, flagellum distinctly incrassate towards apex. Eyes and ocelli absent. In profile view, dorsum of alitrunk straight and flat, very slightly convex, posterodorsal corner of propodeum rounded. In dorsal view, alitrunk roughly rectangular, lateral sides weakly impressed at midlength. In profile view petiolar node roughly rectangular, very thick, anterior face straight, dorsal and posterior faces roundly convex, anterodorsal angle blunt, posterodorsal angle indistinct. Subpetiolar process large, roughly rectangular, posteroventrally pointed. In dorsal view petiolar node broader than long, width: length = 11: 8, anterior face straight, posterior face and lateral sides roundly convex. Dorsum of pygidium slightly depressed, lateroposterior margins with 6 minute peg-like spines on each side. Sting extruding. Mandibles, head, and alitrunk with sparse large punctures, interspace smooth and shining, distance between punctures larger than or equal to diameter of a puncture. Sides of alitrunk and petiolar node with sparse fine punctures, interspace granulate, less shining. Gaster with punctures from which setae arising, interspace smooth. Dorsum of the whole body with a few suberect hairs and dense decumbent pubescences. Antennal scapes and tibiae of legs with a few suberect hairs and dense decumbent pubescences. Body in color yellowish brown, mandibles and antennae dark reddish brown, legs brownish yellow.

Paratype workers: TL 2.3-3.6, HL 0.53-0.77, HW 0.43-0.73, CI 79-91, SL 0.27- 0.40, SI 50-62, PW 0.30 – 0.53, AL 0.67 – 1.00, ML 0.27-0.43, PL 0.20-0.30, PH 0.23-0.43, DPW 0.22-0.40, LPI 117-150, DPI 108-138 (10 measured). As holotype, but body varying in size, color brownish yellow to dark reddish brown.

Borowiec (2009) - HW 0.53–0.68, HL 0.63–0.74, SL 0.30–0.36, MH 0.38–0.44, ML. 0.75–0.94, PrW 0.36–0.49, PW 0.29–0.36, PL 0.24–0.29, IIIAW 0.40–0.49, IIIAL 0.29–0.33, IVAW 0.53–0.64, IVAL 0.30–0.37, FFeL 0.38–0.46, HFel 0.36–0.45, FTiL 0.31–0.38, HTiL 0.38–0.48, FBaL 0.19–0.23, HBaL 0.28–0.35, CI 109–119, MI 197–214, PI 81–83 [2 measured].

Head slightly longer than wide and widest at about midlength; sides parallel, convex. Vertexal margin concave. Parafrontal ridges completely absent. Mandibles triangular; when closed, basal margin not separated from anterior clypeal region by gap. Basal margin meeting masticatory at right angle; masicatory margin with fine crenulation. Laterolypeal teeth small, blunt, and projecting forwards. Antennae 12-segmented. Palp formula 2,2 (after Xu 2000).

Mesosoma moderately stout, rectangular in dorsal view; dorsal surface flattened, bordered at lateral sides by distinct angle but not marginate. Openings of propodeal spiracles irregularly circular, directed sideways. Declivous face of propodeum immarginate above propodeal lobes. Propodeal lobes well developed, broadly rounded. Front femur moderately short and broad, laterally compressed.

Petiole wider than long, with well developed dorsal and posterior faces. Subpetiolar process relatively narrow and short, simple with ventral margin straight, evenly sloping towards posterior end; semi-translucent narrowing present along posterior two thirds of ventral margin.

Abdominal tergite III wide relative to following segment, in side view the whole segment is smaller than following, but with developed anterior, perpendicular face.

Pygidial field small, with five to nine modified, peg-like setae on each side, arranged in one or two rows. Number and arrangement of setae varying with worker size.

Hypopygidium unarmed.

Mandibles densely sculptured with large, deep punctures and interspaces smooth and shining. Head with large but shallow, regular punctures, spaced from about half to more than once their diameter. Similar sculpture on dorsal surface of mesosoma, with punctures more shallow. All interspaces smooth and shining. Lateral sides of promesonotum with small punctures in upper part and extremely finely microreticulate, appearing matt; remaining mesosoma and sides of petiole similarly microreticulate.

Body pilosity composed of (1) dense, decumbent or subdecumbent hairs present on head, mesosoma, and abdominal segments and (2) moderately abundant, twice to more than three times longer than preceding, mostly suberect hairs present on head, mesosomal dorsum, petiole and posterior margins of gastral segments. Outer surface of middle tibiae without modified setae.

Color: body unicolored, yellowish.

Type Material
Holotype: worker, No. A97- 2064, 730 m, Bubang Village, Mengla County, Yunnan Province, from a colony constructs nest in soil in seasonal rain forest, 1997-VIII-17 (ZENG Guang). Paratypes: 34 workers, from the same colony as the holotype and with same data as holotype; 18 workers, No.A98- 775, 1,040 m, Longlin Village, Mengla County, Yunnan Province, from a soil sample in deciduous monsoon forest, 1998-III-14 (ZENG Guang). The type specimens are deposited in the Insect Collection, Faculty of Resources, Southwest Forestry College, Kunming, Yunnan Province, P1 R1 China.

Borowiec (2009) - Holotype and paratype workers, ISAS, (MCZC paratypes examined).

References based on Global Ant Biodiversity Informatics

 * Borowiec M. L. 2009. New ant species related to Cerapachys sexspinus and discussion of the status of Yunodorylus (Hymenoptera: Formicidae). Zootaxa 2069: 43-58.
 * Borowiec M. L. 2009. New species related to Cerapachys sexspinus and discussion of the status of Yunodorylus. Zootaxa 2069: 43-58.
 * Jaitrong W.; Nabhitabhata, J. 2005. A list of known ant species of Thailand. The Thailand Natural History Museum Journal 1(1): 9-54.
 * Song Y., Z. Xu, C. Li, N. Zhang, L. Zhang, H. Jiang, and F. Mo. 2013. An Analysis on the Ant Fauna of the Nangun river Nature Reserve in Yunnan, China. Forest Research 26(6): 773-780.
 * Xu Z. H. 2000. Two new genera of ant subfamilies Dorylinae and Ponerinae (Hymenoptera: Formicidae) from Yunnan, China. Zoological Research 21: 297-302.