Crematogaster keris, Hosoishi, 2020

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 : 763-765

Crematogaster keris , new species

( Figs. 3 , 4 )

Material examined. Holotype (worker) ( FRIM) from Malaysia, Endau Rompin National Park , Station 1 , coll. H. Kojima, 6 July 2003 (fogging).

Paratypes: 14 workers ( BMNH, CASC, FRIM, HNHM, IEBR, ITBC, KUEC, MBBJ, MCZC, MHNG, NHMB, NHMW, THNHM, ZRC), same data as holotype.

Non-type material examined. 20 workers ( KUEC), same data as holotype; 1 worker ( KUEC), Malaysia, Sarawak, Miri, Lambir National Park , Tower Region , coll. T. Yumoto, 20 August 1995 (from Myrmecodia ).

Diagnosis of worker. Anterior portion 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: Holotype and paratype workers (n =15). HW 0.77–1.13; HL 0.71–1.07; CI 102–109; SL 0.66–0.88; SI 69–91; EL 0.17–0.24; PW 0.45–0.66; WL 0.77–1.21; PSL 0.24–0.48; PtL 0.21–0.35; PtW 0.22–0.39; PtH 0.14–0.22; PpL 0.13–0.25; PpW 0.20–0.32; PtHI 61–71; PtWI 99–115; PpWI 124–167; WI 80–92.

General description of worker. Workers with polymorphism in size.

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

Labrum broader than long; median cleft weakly developed; labral tubercle absent; distal area of the outer face with three to four stout setae. Maxilla with maxillary comb; transverse stipital groove absent; stipe subrectangular; maxillary palp 5-segmented; four apical segments longer than broad. Labium with sclerotised prementum on ventral surface; subglossal brush present; paraglossa with sensory peg at distal end; labial palp 3-segmented; apical segment longer than broad. Palp formula (5, 3).

Pronotum with weak ridges on dorsolateral margin. In lateral view, mesonotum posteriorly with indistinct 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 slightly larger than vertical diameter, located on posterolateral corner of propodeum in lateral view. Propodeal spines long, directed posterolaterally in dorsal view.

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.

Sparsely hirsute with erect 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 pairs of longer setae, mixed with shorter setae on the sides. Dorsum of promesonotum with long erect setae and short suberect setae. Fourth abdominal tergite with sparse erect to suberect setae.

Dorsal surface of head longitudinally rugose on anterior half, but relatively smooth on frons and posterior half; longitudinal rugulae surrounding antennal sockets and on gena. Clypeus with weak longitudinal rugulae. Pronotum striated with feeble rugulae anteriorly. Mesonotum weakly striated with feeble rugulae near lateral ridge. Lateral surface of pronotum smooth and shiny. Mesopleuron smooth in small worker, but weakly sculptured with feeble rugulae in large worker. Lateral surface of propodeum smooth and shiny. Propodeal dorsum and declivity smooth and shiny.

Body colour reddish-brown.

Distribution and biology. This species is known from Malaysia (Peninsula, Borneo) ( Fig. 1 ). The type specimens were collected by canopy fogging and the Bornean specimen was collected from the ant-plant Myrmecodia .

Etymology. The species name ‘keris’ is directly adopted from the Malayan asymmetrical dagger of the same name, a traditional weapon of indigenous Malays, referring to the elongated propodeal spines of the species. The name is treated as a noun in apposition.

Notes. This species is similar to C. cornuta , but can be distinguished by the smooth surface of posterior half of head and propodeum.

Figures

Fig. 3. Crematogaster keris, KUEC paratype worker from Malaysia (HW, 1.02; WL, 1.09). A, body in lateral view; B, full-face view of head; C, dorsal view of mesosoma; D, dorsal view of petiole and postpetiole.

Fig. 4. Mouthparts of C. keris worker. A, labrum in outer view; B, left maxilla in outer view; C, labium in lateral view. Abbreviations: Ca = cardo; Ga = galea; Gls = glossa; Hyp = hypopharynx; Lbp = labial palp; Mxco = maxillary comb; Mxp = maxillary palp; St = stipes; Prgls = paraglossa; Prm = prementum; Sglb = subglossal brush.

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