Platythyrea clypeata

Platythyrea clypeata occurs in lowland (200–300 m alt) and inhabits primary and disturbed forests. All colonies of this species were collected from dead wood on the forest floor in an advanced stage of decomposition. (Phengsi et al. 2018).

Identification
Phengsi et al. (2018) - Platythyrea clypeata and Platythyrea janyai are very similar in general appearance as they share the following characteristics: body reddish brown; frontal lobe narrow; frontal carinae closely spaced and strongly narrowed posteriorly; mandible triangular, its masticatory margin with a large apical tooth, followed by 9–10 smaller teeth, large and smaller teeth alternating; propodeal spiracle opening elliptical; in dorsal view posterior margin of petiole convex without spines. However, Platythyrea janyai can be easily separated from Platythyrea clypeata by the following characteristics: head relatively shorter (CI 72–74 in Platythyrea janyai; CI 61–69 in Platythyrea clypeata); eye clearly larger (EL 0.20 mm with eleven ommatidia on longest axis in Platythyrea janyai; EL 0.10 mm with five ommatidia on longest axis in Platythyrea clypeata); eye convex (flat in Platythyrea clypeata); dorsum and lateral face of head finely micropunctate without foveae (finely punctate with dense shallow foveae in Platythyrea clypeata); in profile view petiole clearly longer than high and in dorsal view node of petiole anteriorly as broad as posteriorly (slightly longer than high and in dorsal view node of petiole slightly narrower posteriorly in Platythyrea clypeata); ventral outline of petiole weakly convex (feebly concave in Platythyrea clypeata). No overlap is observed in HW / SL between the species. Platythyrea janyai (Malay Peninsula: S Thailand and W. Malaysia) is distinctly allopatric with Platythyrea clypeata (known from from Sri Lanka, Vietnam, Laos, and east Thailand).

Distribution
China (Yunnan Province); Sri Lanka; Southeast Asia.

Distribution based on Regional Taxon Lists
Oriental Region: Laos, Sri Lanka, Thailand, Vietnam. Palaearctic Region: China.

Nomenclature

 *  clypeata. Platythyrea clypeata Forel, 1911d: 378 (q.) "Pays de Mois" (S.E. Asia). Xu & Zeng, 2000: 214 (w.). Senior synonym of thwaitesi: Brown, 1975: 8.
 * thwaitesi. Platythyrea thwaitesi Donisthorpe, 1931b: 496 (q.) SRI LANKA. Junior synonym of clypeata: Brown, 1975: 8.

Worker
Phengsi et al. (2018) - TL 5.74–6.20 mm; HL 1.29–1.39 mm; HW 0.86– 0.89 mm; SL 1.12–1.18 mm; EL 0.10 mm; WL 1.85–2.05 mm; PL 0.66–0.73 mm; PH 0.46–0.53 mm; PW 0.40–0.43 mm; CI 61–69, EI 11, SI 125–138.

Head. Head in full-face view rectangular, clearly longer than broad, with sides weakly convex or almost parallel, occipital corner roundly convex, and posterior margin feebly concave; antennal scape slender, relatively short, slightly extending beyond posterolateral corner of head (by 1/4 of its length); clypeus narrow, in profile with median portion distinctly convex, in full-face view lateral portion relatively broad and anterior margin clearly convex; mandible triangular, its masticatory margin with a large apical tooth, followed by ten smaller teeth (including basal tooth), large and smaller teeth alternating, but the series as a whole decreasing in size; basal margin of mandible without denticle; eye flat, located laterally at anterior to mid-length of head, very small, 0.10 mm in maximum diameter, with five ommatidia along longest axis; distance between mandibular base and anterior margin of eye approximately three times as long as maximum eye length; with head in lateral view, distance between posterior margin of eye and occipital corner of head 2.7 times as long as distance between mandibular base and anterior margin of eye; frontal lobes close to each other and rounded; frontal carinae strongly narrowed posteriorly.

Mesosoma elongate, in profile with almost straight dorsal outline; promesonotal suture distinct; mesopleuron demarcated from mesonotum and metapleuron by shallow furrows; propodeum in profile with almost straight dorsal outline; propodeal junction obtusely angulated; declivity of propodeum shallowly concave; seen from back propodeal declivity rounded above; propodeal spiracle opening elliptical; legs relatively long.

Petiole cylindrical and sessile, slightly longer than high and clearly longer than broad, its dorsal outline almost straight; in profile posterodorsal corner forming an acute angle; declivity deeply concave; in dorsal view node rectangular, slightly narrower posteriorly, its posterior margin convex and with shallow median concavity; subpetiolar process developed, located anteroventrally, subtriangular, its apex truncate and pointed forward; ventral outline of petiole feebly concave.

Sculpture. Dorsum of head finely punctate; lateral face of head behind, above and below eye punctate with dense foveae; dorsum of mesosoma with fine micropunctures similar to those on dorsum of head; lateral faces of pronotum, metapleuron and propodeum punctate with sparse shallow foveae; petiole finely micropunctate; gastral tergites I and II finely reticulate; antennal scape finely micropunctate; coxae microreticulate with smooth and shiny interspaces.

Pubescence white, very short and fine; setae present on tip of gaster. Colouration. Head, mesosoma, petiole, and gaster reddish brown to dark brown (tip of gaster yellowish); antenna and legs yellowish brown to reddish brown (flagellum paler than scape).

Queen
Phengsi et al. (2018) - (n = 2). TL 7.49 mm; HL 1.52 mm; HW 1.06 mm; SL 1.32 mm; EL 0.20 mm; WL 2.31 mm; PL 0.79 mm; PH 0.73 mm; PW 0.46 mm; CI 69, EI 18, SI 125. Dealate. Body size slightly larger than worker. Head. Head in full-face view rectangular, clearly longer than broad with convex sides and almost straight posterior margin, occipital corner roundly convex; antennal scape extending beyond posterolateral corner of head by approximately 1/4 of its length; eye relatively large and convex, located anterior to mid-length of head, 0.20 mm in maximum diameter with ca. 17 ommatidia on the longest axis; frontal lobe and frontal carina similar to those in worker caste; distance between anterior margin of eye and mandibular base almost as long as eye length; ocelli clearly absent. Mesosoma in profile with slightly convex dorsal outline; pronotum long and broad; mesoscutum trapezoidal, anterior edge clearly convex in dorsal view, separated from mesoscutellum by a shallow but wide suture and from pronotum by narrow suture; parapsidal lines indistinct, relatively long, straight and running anteriorly to mid-length of mesoscutum; mesoscutellum almost as long as broad; metanotum very short, separated from mesoscutellum and propodeum by deep grooves; propodeum relatively long; mesopleuron broad, anepisternum not demarcated from katepisternum; propodeal junction obtusely angulated; declivity of propodeum shallowly concave; seen from back propodeal declivity rounded above. Petiole in profile view relatively short, rhombus, almost as long as high, its anterior margin weakly convex while posterior margin concave; declivity of petiole shallowly concave; subpetiolar process low and subtriangular, located anteroventrally, its apex pointed forward; ventral outline of petiole feebly concave. Gaster larger than in worker.

Sculpture, colouration, and setae similar to those of worker caste.

Type Material
The syntype alate queen from “Pays de Moïs”, Cochinchina française (S.E. Asia), deposited in (not examined).

Determination Clarifications
Phengsi et al. (2018) - Xu and Zeng (2000) identified a worker from China as P. clypeata. It has a body size much larger than the holotype (alate queen) of P. clypeata (HW 1.20 mm in the Chinese specimen; HW 1.00 mm in the holotype). In general, queens in this genus are slightly larger than workers, with corresponding modifications of thoracic sclerites (Ito 1994, Schmidt and Shattuck 2014). Thus, the Chinese specimen should be re-identified.

References based on Global Ant Biodiversity Informatics

 * Chapman, J. W., and Capco, S. R. 1951. Check list of the ants (Hymenoptera: Formicidae) of Asia. Monogr. Inst. Sci. Technol. Manila 1: 1-327
 * Dias R. K. S. 2002. Current knowledge on ants of Sri Lanka. ANeT Newsletter 4: 17- 21.
 * Dias R. K. S. 2006. Current taxonomic status of ants (Hymenoptera: Formicidae) in Sri Lanka. The Fauna of Sri Lanka: 43-52. Bambaradeniya, C.N.B. (Editor), 2006. Fauna of Sri Lanka: Status of Taxonomy, Research and Conservation. The World Conservation Union, Colombo, Sri Lanka & Government of Sri Lanka. viii + 308pp.
 * Dias R. K. S., K. R. K. A. Kosgamage, and H. A. W. S. Peiris. 2012. The Taxonomy and Conservation Status of Ants (Order: Hymenoptera, Family: Formicidae) in Sri Lanka. In: The National Red List 2012 of Sri Lanka; Conservation Status of the Fauna and Flora. Weerakoon, D.K. & S. Wijesundara Eds., Ministry of Environment, Colombo, Sri Lanka. p11-19.
 * Donisthorpe H. 1931. Descriptions of some new species of ants. Annals and Magazine of Natural History (10)8: 494-501.
 * Guénard B., and R. R. Dunn. 2012. A checklist of the ants of China. Zootaxa 3558: 1-77.
 * Phengsi N., W. Jaitrong, J. Ruangsittichai, and S. Khachonpisitsak. 2018. A sibling species of Platythyrea clypeata Forel, 1911 in southeast Asia (Hymenoptera, Formicidae, Ponerinae). ZooKeys 729:87-102.
 * Xu Z. and Zeng G. 2000. Discovery of the worker caste of Platythyrea clypeata Forel and a new species of Probolomyrmex Mayr in Yunnan, China (Hymenoptera: Formicidae). Entomologia Sinica 7(3): 213-217.
 * Zryanin V. A. 2011. An eco-faunistic review of ants (Hymenoptera: Formicidae). In: Structure and functions of soil communities of a monsoon tropical forest (Cat Tien National Park, southern Vietnam) / A.V. Tiunov (Editor). – M.: KMK Scientific Press. 2011. 277 р.101-124.