Polyrhachis maryatiae

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Polyrhachis maryatiae
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Formicinae
Tribe: Camponotini
Genus: Polyrhachis
Subgenus: Myrmhopla
Species: P. maryatiae
Binomial name
Polyrhachis maryatiae
Kohout, 2007

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Specimen Labels

P. maryatiae is evidently a rather rare species known only from a few collections made at higher elevation rainforest localities. It appears that colonies of P. maryatiae nest high in the rainforest canopy and the workers only occasionally descend to ground level. The type series specimens were collected foraging over the trunks and crowns of freshly felled trees at the Ginseng Camp, Maliau Basin Conservation Area at an elevation of about 700 m. Cutting down the trees, to make a suitable clearing for the camp, brought at least one colony to the ground. After the collection of most of the specimens in the first two days, they frequency rapidly declined and within less than a week from the first encounter no more specimens were seen foraging over the area. (Kohout 2007)

Identification

Kohout (2007) - Polyrhachis maryatiae is closely related to Polyrhachis armata, a very widespread and somewhat variable south-east Asian species that also occurs in Borneo. These two species share the distinctive coarse sculpturation of the head and mesosoma. However they differ in several significant characters. Polyrhachis maryatiae is generally larger (HL 2.78-3.03 in maryatiae versus HL 2.43 and 2.50 in syntypes of defensa and pandarus), has more prominent sculpturation and distinctly longer pronotal and propodeal spines. The anterior face of the petiole in profile is smoothly rounded dorsally, forming a continuous curve with the outline of the petiolar spines. In contrast, the petiole in P. armata has the anterior and posterior faces subparallel and a more-or-less flat dorsum with the anterior margin distinctly raised. Consequently, the profile of the petiole features a distinct raised prominence between the anterior face and the base of the propodeal spines. In addition, the gaster is rather smooth and polished in P. maryatiae, while it is distinctly reticulate-punctate and opaque in P. armata.

Distribution

Distribution based on Regional Taxon Lists

Indo-Australian Region: Borneo, Indonesia, Malaysia (type locality).


Distribution based on AntMaps

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Distribution based on AntWeb specimens

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Biology

Castes

Nomenclature

The following information is derived from Barry Bolton's New General Catalogue, a catalogue of the world's ants.

  • maryatiae. Polyrhachis (Myrmhopla) maryatiae Kohout, 2007b: 2, figs. 1, 2 (w.q.) BORNEO (Sabah).

Unless otherwise noted the text for the remainder of this section is reported from the publication that includes the original description.

Description

Worker

(holotype cited first): TL c.11.39, 10.68-11.94; HL 2.99, 2.78-3.03; HW 2.37, 2.12-2.46; CI 79, 76-81; SL 3.88, 3.63-3.98; SI 164, 162-171; PW 1.87, 1.72-2.06; MTL 5.24, 4.79-5.29 (12 measured).

Mandibles with 5 teeth. Anterior clypeal margin produced into two, blunt, anterolaterally projecting tooth-like prominences, their inner margins continuous medially, forming a ‘U’ shaped median emargination. Clypeus in profile straight along poorly defined median carina; posteriorly rounding into well impressed basal margin. Frontal triangle distinct. Frontal carinae sinuate, relatively short with highly raised laminate lobes; central area rather narrow with short median furrow. Antennal scapes somewhat flattened at their bases. Sides of head in front of eyes strongly convex; behind eyes sides converge into a rather narrow, distinctly raised occipital margin. Eyes strongly convex but in full face view not reaching lateral cephalic outline. Mesosoma totally laterally immarginate. Pronotum with pair of strong, acute, anterolaterally directed spines, rising dorsally from their bases and curving weakly downwards at midlength. Promesonotal suture distinct. Mesonotum in profile evenly convex; metanotal groove lacking. Propodeum armed with two acute, long spines, arising dorsolaterally and posteriorly, curving at midlength and becoming more posteriorly and horizontally directed. Propodeal dorsum descending into steep declivity in medially uninterrupted line. Petiole with anterior and posterior faces converging towards narrowly rounded dorsum, armed with a pair of acute, dorsolaterally directed spines that form an open ‘U’ shape in dorsal view. Anterior face of first gastral segment widely rounding onto dorsum of gaster.

Mandibles very finely, mostly longitudinally rugose. Clypeus and frontal triangle weakly reticulate-rugose with numerous small punctures breaking reticulate pattern; intensity of sculpturation markedly increasing posteriorly with rest of head, mesosoma and petiole very deeply and coarsely foveolate-rugose; numerous additional small punctures distributed in irregular patches over most body surfaces, except gaster which is smooth and highly polished.

Mandibular masticatory borders and outer margins with numerous short to medium-length, reddish-golden hairs, curving closely to surface of mandibles. Median emargination of anterior clypeal margin with a few longer, anteriorly directed setae and shorter setae fringing margin laterally. A few very short hairs fringing apex of antennal scapes. Anterior face of fore coxae and ventral faces of middle and hind coxae with very few medium-length, downward-directed hairs. Gaster with only a few erect hairs lining apical segments dorsally; distinctly longer, more abundant hairs lining segments on gastral venter. Extremely short, very diluted, appressed pubescence over most dorsal surfaces, noticeably thicker on gastral dorsum.

Black throughout, except reddish-yellow condylae and golden spurs on front legs.

Queen

TL c.14.26; HL 3.40; HW 2.68; CI 79; SL 4.18; SI 156; PW 3.07; MTL 5.59 (1 measured).

Queen similar to worker with usual differences indicating caste, including three ocelli, complete thoracic structure and wings. Body sculpturation, pilosity and colour essentially as in worker.

Type Material

HOLOTYPE: East Malaysia, Sabah, Maliau Basin, Ginseng Camp, 04º44’N, 116º55’E, c.700 m, 27.ii - 11.iii.2005, primary rainforest, R.J. Kohout & Effazilla Waty (RJK acc. # 05.17) (worker).

PARATYPES: data as for holotype (23 workers, 1 alate queen). Type deposition: Holotype and 2 paratype workers in Institute for Tropical Biology and Conservation, most paratype workers and paratype queen in Queensland Museum; 2 paratype workers each in Australian National Insect Collection, The Natural History Museum, California Academy of Sciences, Museum of Comparative Zoology and National Museum of Natural History.

References