Polyrhachis tonsilis

Polyrhachis tonsilis
Scientific classification
Kingdom:	Animalia
Phylum:	Arthropoda
Class:	Insecta
Order:	Hymenoptera
Family:	Formicidae
Subfamily:	Formicinae
Tribe:	Camponotini
Genus:	Polyrhachis
Species:	P. tonsilis
Binomial name
	Polyrhachis tonsilis; Santschi, 1928

Until recently this species was considered to be a junior synonym of Polyrhachis bihamata and, therefore, has received very little discussion in the scientific literature. Essentially nothing is known concerning its biology.

Photo Gallery

Zettel (2019), Fig. 7: Polyrhachis (Polyrhachis) tonsilis, lectotype worker, lateral view.
Zettel (2019), Figs. 8–9: Polyrhachis (Polyrhachis) tonsilis, lectotype worker, full-face view (8) and dorsal view of mesosoma and petiole (9). © Daniela Lehner.

Identification

Zettel (2019) - Medium-size, body length ca. 9.7–10.0 mm, head width 2.12–2.18 mm. Bicoloured: head, antenna, tips of spines, and tarsi black; mesosoma, petiole and gaster tergite 1 predominantly pale reddish orange; other tergites and tibiae mostly dark brown; femora reddish brown. Short pubescence variably dense, sparse and thin on head and gaster, dense and long on mesosoma and petiole. Standing setae lacking on scape, mesosoma and petiole, reduced in number and length on head and gaster tergites. Surface mostly matt, shiny on clypeus and gaster. Eyes in full-face view just not reaching outline of head. Dorsum of propodeum laterally rounded, posteriorly with a pair of short transverse, somewhat angular carinae; spiracles distinctly elevated. Petiole columnar; petiolar spines hooked, parallel for most of length. Gaster tergites 1–4 without large punctures.

Polyrhachis tonsilis shows a mixture of characters found in Polyrhachis olybria and Polyrhachis bihamata (see also Kohout 1998), with a closer affinity to the latter. In P. olybria the median ocellus is absent or strongly reduced (as in P. tonsilis), and populations with strongly reduced pilosity do exist. However, all studied populations of P. olybria have some long setae on the underside of the head which are lacking in P. tonsilis. Similarities with P. bihamata are the posteriorly pointing pronotal spines (laterally pointing in P. olybria) and the low, short, transverse, paired carinae of the propodeum (pair of teeth in P. olybria). Polyrhachis tonsilis also differs from P. bihamata by a narrower pronotal dorsum. Polyrhachis tonsilis also resembles Polyrhachis lacroixi by the strongly shiny gaster tergites. However, P. lacroixi can be readily distinguished from P. tonsilis by a single median tubercle on the propodeum and by the dispersed large punctures on gaster tergites 1–4.

Keys including this Species

Key to Polyrhachis (Polyrhachis) species

Distribution

Latitudinal Distribution Pattern

Latitudinal Range: 3.3° to 3.3°.


North Temperate	North Subtropical	Tropical	South Subtropical	South Temperate

Source: Zettel, 2019

Distribution based on Regional Taxon Lists

Indo-Australian Region: Indonesia (type locality).

Distribution based on AntMaps

Distribution based on AntWeb specimens

Check data from AntWeb

Countries Occupied

Number of countries occupied by this species based on AntWiki Regional Taxon Lists. In general, fewer countries occupied indicates a narrower range, while more countries indicates a more widespread species.

Estimated Abundance

Relative abundance based on number of AntMaps records per species (this species within the purple bar). Fewer records (to the left) indicates a less abundant/encountered species while more records (to the right) indicates more abundant/encountered species.

Biology

Castes

Nomenclature

The following information is derived from Barry Bolton's Online Catalogue of the Ants of the World.

tonsilis. Polyrhachis (Polyrhachis) bihamata var. tonsilis Santschi, 1928h: 133 (w.) INDONESIA (Sumatra).
Junior synonym of bihamata: Hung, 1970: 16.
Status as species: Zettel 2019: 65.

Type Material

Lectotype (worker, CASENT0912165; designated by Zettel, 2019: 65): “Corporaal Sumatra O. K. Sibolangit 1918” and one paralectotype (worker) from the same locality, both in the Natural History Museum Basle.

Taxonomic Notes

Zettel (2019) - Santschi (1928) described four workers from Sibolangit in North Sumatra and named them “Polyrhachis (Polyrhachis) bihamata Drury v. tonsilis v. n.”. Hung (1970) synonymized this taxon with P. bihamata, but the synonymy was questioned by Kohout (1998), and shortly discussed by Kohout (2014). Kohout (2014) also mentioned a possible synonymy of tonsilis and var. minor Karavaiev, 1927 from Java, which I have not seen. However, this is only of zoogeographical importance, because var. minor Karavaiev is a primary homonym of P. armata var. minor Forel, 1886.

I have studied the two syntypes from the Santschi Collection in the Natural History Museum Basle. The whereabouts of the other two specimens is unclear. For the reason of nomenclatural stability, I fix the identity of the species by designating the specimen figured by AntWeb (CASENT0912165) as the lectotype.

Description

References

Hung, A. C. F. 1970. A revision of ants of the subgenus Polyrhachis Fr. Smith (Hymenoptera: Formicidae: Formicinae). Orient. Insects 4: 1-36.
Kohout, R. J. 1998. New synonyms and nomenclatural changes in the ant genus Polyrhachis Fr. Smith (Hymenoptera: Formicidae: Formicinae). Mem. Qld. Mus. 42: 505-531.
Kohout, R.J. 2014. A review of the subgenus Polyrhachis (Polyrhachis) Fr. Smith (Hymenoptera: Formicidae: Formicinae) with keys and description of a new species. Asian Myrmecology 6, 1–31.
Santschi F. 1928. Fourmis de Sumatra, récoltées par Mr. J. B. Corporaal. Tijdschrift voor Entomologie 71: 119-140.
Zettel, H. 2019. Two new species from Malaysia and further taxonomic notes on Polyrhachis s.str. (Hymenoptera: Formicidae). Zeitschrift der Arbeitsgemeinschaft Österreichischer Entomologen 71: 57-73.