Crematogaster cornuta Crawley, 1924

Hosoishi, Shingo, 2020, Taxonomic review of the Crematogaster ransonneti-group in Asia, with description of a new species from Malaysia (Hymenoptera: Formicidae: Myrmicinae), Raffles Bulletin of Zoology 68, pp. 759-768 : 761-763

Crematogaster cornuta Crawley, 1924

( Fig. 2 )

Crematogaster (Acrocoelia) cornuta Crawley, 1924: 395 , worker, queen, male. Combination in Crematogaster (Crematogaster) : Bolton, 1995: 166; Blaimer, 2012a: 55.

Type material examined. 1 syntype worker ( BMNH), Indonesia, Sumatra, Pantjuran Gading, Kurintji (BMNH[E] 1015160 ), coll. Donisthorpe, April 1934.

Non-type material examined. 10 workers ( KUEC), Indonesia, Sumatra, Solok district, Mt. Talang , coll. R. Satria, 25 February 2011.

Diagnosis of worker. Dorsal surface of head with longitudinal rugulae. Mesonotum with lateral ridge in lateral view. Propodeal spine very long. In dorsal view petiole diamond-shaped, broadest at mid-length. Postpetiole weakly bilobed posteriorly, but without longitudinal median sulcus.

Measurements and indices: Non-type workers (n = 10).

HW 0.97–1.13; HL 0.94–1.08; CI 102–109; SL 0.84–0.97; SI 82–90; EL 0.18–0.21; PW 0.60–0.72; WL 1.09–1.31; PSL 0.30–0.63; PtL 0.34–0.41; PtW 0.31–0.39; PtH 0.19–0.25; PpL 0.18–0.23; PpW 0.28–0.33; PtHI 55–62; PtWI 89–99; PpWI 135–170; WI 84–91.

General description of worker. Workers with weak intracolonial size variation.

Head broader than long in full-face view, posterior margin almost straight, posterior corner rounded. Frontal carina extending to mid-length of head. Occipital carina developed. Mandible with four teeth, apical and subapical teeth large. Anterior clypeal margin slightly concave in median portion. Compound eyes slightly projecting beyond lateral margins of head in full-face view. Scape reaching posterior corner of head. Antennal club 3-segmented.

Pronotum with indistinct ridges on dorsolateral margin. In lateral view, mesonotum posteriorly with longitudinal ridges. Mesonotum slightly higher than pronotum in lateral view. Metanotal groove straight in dorsal view, forming a deep concavity between mesonotum and propodeum. Metapleural gland opening slit-shaped. Propodeal spiracles dorsoventrally oval, its horizontal diameter larger than vertical diameter, located on posterolateral corner of propodeum in lateral view. Propodeal spines long, directed posterolaterally.

Petiole diamond-shaped, broadest at mid-length in dorsal view; spiracle situated at midportion between dorsal and ventral margin of petiole in lateral view, directed laterally. Subpetiolar process undeveloped. Postpetiole weakly bilobed, but without longitudinal median sulcus in dorsal view. Petiole wider than postpetiole in dorsal view.

Abundantly hirsute, with suberect setae. Scape with abundant suberect to decumbent setae. Dorsal face of head with erect to suberect setae. Clypeus with suberect setae; one pair of longer setae directed medially on anteriormost portion. Anterior clypeal margin with two to three pairs of longer setae, mixed with some shorter setae on the sides. Dorsum of pronotum and propodeum with long erect setae and short suberect setae. Fourth abdominal tergite with sparse erect to suberect setae.

Dorsal surface of head longitudinally rugose; gena with longitudinal rugulae. Clypeus with weak longitudinal rugulae. Pronotum striated with feeble rugulae. Lateral surface of pronotum superficially smooth. Mesonotum weakly striated with feeble rugulae. Mesopleuron and lateral surface of propodeum striated with distinct rugulae. Propodeal dorsum with longitudinal rugulae; propodeal declivity smooth and shiny.

Body colour reddish-brown.

Distribution. This species is known only from Indonesia (Sumatra) ( Fig. 1 ).

Notes. The Sumatran specimens are morphologically most similar to the BMNH syntype worker of C. cornuta . Based on worker morphology, the Sumatran specimens are herein determined as C. cornuta .

This species is similar to C. keris , but can be distinguished by the dorsal surface of head and propodeum with longitudinal rugulae.

Figures

Fig. 2. Crematogaster cornuta, non-type worker from Sumatra (HW, 1.08; WL, 1.24). A, body in lateral view; B, full-face view of head; C, dorsal view of mesosoma; D, dorsal view of petiole and postpetiole.

Fig. 1. Distribution map of Crematogaster cornuta, C. keris, and C. ransonneti. Open circle = C. cornuta; open square = C. keris; open triangle = C. ransonneti.