Crematogaster maryatii

An endemic Borneo member of a group of Crematogaster species associated with Macaranga plants in Sumatra, Borneo, and Peninsula Malaysia.

Identification
Feldhaar et al. (2016) - A member of the Crematogaster borneensis group. Worker: Very short propodeal spines, sometimes absent, scape index (SI)> 0.65, head slightly longer than wide (CI 0.94 - 1.02), petiole as wide or wider than postpetiole, PI > 0.98, RLEG usually < 0.7. Queen: EL 0.34 - 0.38mm, REL 0.28-0.34, OD1 > OW, PI usually > 1.0 (to 1.12).

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

Biology
Feldhaar et al. (2016) - Crematogaster maryatii is endemic to Borneo and is associated with hosts of the section Pachystemon only (M. havilandii, M. hypoleuca, M. motleyana, locally M. angulata, rarely M. indistincta). The species colonizes waxy as well as non-waxy hosts, but the latter mostly in primary forest habitats, such as M. indistincta (Danum Valley) or M. angulata (Poring Hot Spring at higher elevation). Due to the small-sized queen, small workers and early onset of reproduction (when colonies comprise approximately 500 workers) such hosts in relatively dark primary forest habitats may still sustain colonies of C. maryatii and enable them to reach the reproductive phase. In secondary forest the small queens may be able to colonize small saplings earlier than the larger queens of the captiosa-group (e.g. in M. hypoleuca). Thus, the queens are usually found in the very first internodes developed by saplings (Feldhaar, pers. obs.).

Nomenclature

 *  maryatii. Crematogaster maryatii Feldhaar, Maschwitz & Fiala, 2016: 659, figs. 3.7, S1.6A-D (w.q.) MALAYSIA.

Worker
Paratype. CI 1.0, DPPW 0.14, DPW 0.14, EL 0.08, HL 0.54, HW 0.52, LHT 0.41, LPS 0.055, MTW 0.3, PI 1.01, REL 0.15, RLEG 0.69, SI 0,71, SL 0.37, (TL 2.1), WL 0.59.

CI 0.94-1.02, DPPW 0.14-0.2, DPW 0.14-0.21, EL 0.08- 0.12, HL 0.54-0.65, HW 0.52-0.63, LHT 0.41-0.54, LPS 0.047- 0.063, MTW 0.3-0.38, PI 0.98-1.07, REL 0.15-0.18, RLEG 0.67- 0.72, SI 0.65-0.79, SL 0.37-0.47, (TL 2.1-3.0), WL 0.59-0.73

Colour medium to dark brown with head and gaster a slightly darker shade than alitrunk. Workers monomorphic in size. Total body length of workers ranges from 2.3 mm to 3.0 mm. Head and gaster shiny with smooth surface, alitrunk slightly less shiny and faintly shagreened. All body parts bear appressed pubescent hairs. Long flexuous setae present on head gaster and abdomen: on head especially in frons, on gaster more on the posterior margins of tergites and sternites. Only few setae on alitrunk and one pair each on petiole and postpetiole. Head subquadratic but slightly elongated, usually longer than wide and only slightly rounded on sides. Anterior clypeal margin slightly convex and with a row of long erect setae projecting anteriorly. Occipital margin slightly concavely rounded, occipital lobes rounded. Mandibles relatively short and with four denticles, capable of closing tightly against the clypeus. Denticles increasing continuously in size from most proximate to most distal denticle. Surface of mandibles smooth, covered with short pubescent hairs. Antennae relatively long in comparison to head width (SI 0.65-0.79; usually > 0.7) and covered in short pubescent hair. Terminal three funicular segments form a club, sometimes only the terminal two segments.

Compound eyes elliptically shaped and not protruding over margin of head in full-face view. Pronotum and mesonotum form a convex dome in profile that is flattened dorsally. Anterodorsal surface of pronotum sloping downwards as steep as posterodorsal surface of mesonotum. Metanotal groove slightly notched and clearly developed; promesonotal suture is visible but not prominent.

Propodeal spines very short or nearly absent, but dorsum of the propodeal spiracle with a nodiform elevation. Slope of posterior face of propodeum similar to posterior slope of mesonotum and approximately 45°.

In dorsal view postpetiole always wider than petiole (PI: 0.98-1.07). Both petiole and postpetiole round in dorsal view and nodiform in lateral view. Subpetiolar process usually absent.

Queen
Holotype. CI 0.95, DPPW 0.37, DPW 0.38, EL 0.37, HL 1.17, HW 1.11, LHT 0.82, MTW 0.89, OD1 0.15, OD2 0.06, OW 0.11, PI 1.01, REL 0.31, RLEG 0.41, ROD 0.13, ROD2 0.05, SI 0.6, SL 0.67, (TL 5.5), WL 2.0.

CI 0.90-1.04, DPPW 0.36-0.44, DPW 0.38-0.49, EL 0.34- 0.38, HL 1.09-1.22, HW 1.01-1.2, LHT 0.72-0.95, MTW 0.78- 1.21, OD1 0.15-0.2, OD2 0.06-0.09, OW 0.09-0.11, PI 0.97-1.12, REL 0.28-0.34, RLEG 0.39-0.47, ROD 0.13-0.18, ROD2 0.05- 0.08, SI 0.51-0.6, SL 0.59-0.68, (TL 5.4-6.6), WL 1.74-2.2

Queens small, from 5.4 to 6.6 mm in total body length and uniformly dark brown in colour. Surface of head and gaster smooth and shiny, alitrunk slightly less shiny and faintly shagreened. All body parts bear appressed pubescent hairs. Long flexuous setae present on head gaster and abdomen: on head especially in frons, on gaster more on the posterior margins of tergites and sternites. A row of long erect setae pointing anterior present on the clypeus. Mandibles relatively short, capable of closing tightly against the clypeus.

Head usually longer than wide (CI: 0.90-1.04; mean 0.97). Sides of the head straight and head narrower anterior than posterior. Occipital margin of the head straight. Occipital lobes rounded. Anterior clypeal margin slightly convex. Terminal 3 segments of funiculus forming a distinct antennal club. Antennal scrobes strongly developed, with an acute and marked dorsal margin; the frontal carinae short.

Compound eyes only slightly oval-shaped from lateral view and maximum head width with compound eyes slightly wider than HW (see Fig 3.7, Fig S1.6A and S1.6D). Compound eyes small relative to head length spanning one third or less of HL. Maximum diameter of compound eyes from 0.34 to 0.38 mm. Ocelli relatively small in diameter. The two lateral ocelli widely spaced and the median ocellus always smaller in diameter than the distance between the two lateral ocelli.

Mesoscutum convexly rounded anterodorsally. Mesoscutellum nearly in horizontal plane in lateral view. Propodeum flattened dorsally and drops off steeply posterior of the propodeal spiracle. Mesoscutum relatively short, stretching out over approximately a third of the alitrunk in lateral view. In dorsal view, posterior margin of the propodeum forms a straight line and mesonotum is broadly triangular. Propodeum not armed with spines.

Petiole in dorsal view rounded and node approximately as wide as long. Petiole approximately as wide as postpetiolar node (PI 0.97-1.12). In lateral view the petiole anterodorsally flattened and sloping downwards, and slightly longer than the postpetiole. Postpetiole rounded in lateral view without distinct nodes and subquadratic in dorsal view.

Type Material
Holotype. Queen (to be deposited in, provisional specimen number DG06-263-Q). Tawau Forest Reserve, secondary forest (B. Fiala) Queen from Macaranga hypoleuca; 29.8.2006. Paratype. Worker from same colony as holotype queen (to be deposited in SMNK, provisional specimen number DG06-263-W).

Determination Clarifications
In previous publications by our group this species was referred to as Crematogaster msp. 7 (Fiala et al., 1999; Feldhaar et al., 2003b; Feldhaar et al., 2010).

References based on Global Ant Biodiversity Informatics

 * Feldhaar H., U. Maschwitz, and B. Fiala. 2016. Taxonomic revisions of the obligate plant-ants of the genus Crematogaster Lund (Hymenoptera: Formicidae: Myrmicinae), associated with Macaranga Thouars (Euphorbiaceae) on Borneo and the Malay Peninsula. Sociobiology 63(1): 651-681.