Yunodorylus paradoxus

Known only from the worker caste, the holotype was collected from a soil core.

Identification
Borowiec (2009) - This species is aberrant in many characters as compared with others belonging to the genus and thus easy to recognize. It is the only member of the genus having 11-segmented antennae. The anterior margin of clypeus is conspicuously modified and drawn here into a semi-translucent lamella and laterally forming large, blunt teeth projecting over mandibles. Parafrontal ridges, however very low and reduced, can be seen in this species, as opposed to the others in this group. The petiole is also quite special in having the dorsal surface sloping evenly into posterior end, thus not having well differentiated perpendicular posterior face. Abdominal segment III is unique by being very small compared to the following one, with narrow and rounded anterior faces, as opposed to clearly differentiated, perpendicular portion of tergites and sternites observed in other species. The sculpture of the head and dorsal mesosoma is strong, composed of closely spaced, regular, and umbilicate foveae

Distribution
Known only from Sarawak.

Distribution based on Regional Taxon Lists
Indo-Australian Region: Borneo, Indonesia, Malaysia.

Castes
Known only from the worker caste.

Nomenclature

 *  paradoxus. Cerapachys paradoxus Borowiec, 2009: 51, figs. 6-8, 14 (w.) BORNEO.
 * Combination in Yunodorylus: Borowiec, M.L. 2016: 237.

Worker
Holotype. HW 0.67, HL 0.68, SL 0.37, MH 0.46, ML 0.97, PrW 0.45, PW 0.27, PL 0.30, IIIAW 0.50, IIIAL 0.30, IVAW 0.70, IVAL 0.40, FFeW 0.19, FFeL 0.48, HFeL 0.46, FTiL 0.35, HTiL 0.43, FBaL 0.25, HBaL 0.30, CI 101, PI 111, MI 211.

Workers. HW 0.42–0.67, HL 0.49–0.68, SL 0.23–0.37, MH 0.30–0.46, ML 0.68–0.97, PrW 0.28–0.45, PW 0.19–0.27, PL 0.20–0.30, IIIAW 0.36–0.50, IIIAL 0.22–0.30, IVAW 0.45–0.70, IVAL 0.27–0.40, FFeW 0.12–0.19, FFeL 0.32–0.48, HFeL 0.27–0.46, FTiL 0.26–0.35, HTiL 0.27–0.43, FBaL 0.11–0.25, HBaL 0.14–0.30, CI 101–117, MI 202–227, PI 105–124 [6 measured].

Head almost as wide as long in the largest worker, in the smallest workers slightly longer than wide, and widest at about midlength; sides parallel, convex. Vertexal margin concave. Parafrontal ridges present but not raised, very low, reduced. Mandibles triangular; when closed, basal margin not separated from anterior clypeal region by gap. Basal margin long, meeting masticatory at right angle; masicatory margin with row of small denticles. In full face view, frontal lobes diverging laterally and confluent with lateral portions of clypeus. Lateroclypeal teeth very well developed, consisting of semi-translucent lamella overhanging mandibles; clypeus between teeth also lamellate and converging to frontal lobes medially. Antennae 11-segmented with apparent fusion resulting in 10 segments observed in one flagellum of the smallest specimen examined. Palp formula 2,2.

Mesosoma moderately stout, rectangular in dorsal view; dorsal surface flattened, bordered at the lateral sides by distinct angle but not marginate. Openings of propodeal spiracles irregularly circular, directed outwardly and upwards at angle of 45°. Declivous face of propodeum immarginate above propodeal lobes. Propodeal lobes well developed, broadly rounded. Front femur moderately short and broad, laterally compressed. Metatibial gland visible as small, broadly oval patch of lighter cuticle, diameter about fourth of maximum tibia width.

Petiole slightly longer than wide, with well developed dorsal face sloping gently posteriorly. Subpetiolar process relatively narrow and long; in side view with convex ventral margin and lamella forming broad angulate process.

Abdominal tergite III narrow relative to following segment, in side view the whole segment is small and anteriorly rounded.

Pygidial field small, weakly impressed, with six to eight teeth on each side.

Hypopygidium unarmed. Mandibles densely sculptured with longitudinal striae and small punctures. Head with regular foveae, spaced from about one sixth to wider than their diameter. Similar sculpture on dorsal surface of mesosoma, but foveae somewhat smaller. All interspaces shining. Lateral sides of promesonotum with upper part foveolate, lower reticulate; remaining mesosoma with area above level of propodeal spiracle finely, longitudinally reticulate, and below that level (katepisternum, lower half of pronotal sides) reticulate. Sides of petiole similarly reticulate.

Body pilosity composed of (1) dense, subdecumbent hairs present on, head, mesosoma, and abdominal segments and (2) sparse, more than twice longer than preceding, mostly suberect hairs present on propodeum, petiole, posterior margins of gastral segments, and pygidium. Outer surface of middle tibiae with two or three modified, thick, peg-like setae.

Color: in larger workers bicolored with brownish antennae, mandibles, head and anterior mesosoma, posterior mesosoma and petiole lighter, legs and gaster yellowish. In smaller workers coloration similar or the whole body yellowish.

Type Material
Holotype worker (topmost specimen of three on the pin). MALAYSIA: Sarawak, Gunung Mulu National Park, Kerangas forest, soil core, XII 1978 (N. M. Collins).

Paratypes. 3 workers with same data as holotype [BMNH].

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.
 * Pfeiffer M., and D. Mezger. 2012. Biodiversity Assessment in Incomplete Inventories: Leaf Litter Ant Communities in Several Types of Bornean Rain Forest. PLoS ONE 7(7): e40729. doi:10.1371/journal.pone.0040992
 * Pfeiffer M.; Mezger, D.; Hosoishi, S.; Bakhtiar, E. Y.; Kohout, R. J. 2011. The Formicidae of Borneo (Insecta: Hymenoptera): a preliminary species list. Asian Myrmecology 4:9-58