Myrmica arisana

Wheeler gave no ecological details when he described this species as a variety of M. rugosa. We found a large population of M. arisana living under stones on a south-facing bank by a roadside at 1700 m on Yungfen, Nantou (Taiwan). The stones were close together and almost all housed part of the population. The impression was the stones were connected and that the population comprised several large polycalic nests reminiscent of how Myrmica rubra lives in some European habitats. However, no mature queens were caught (as would be expected if it was M. rubra) indicating that M. arisana is probably not an especially polygynous species. The day was hot and the workers were very aggressive and stung freely. In Chiayi near the Alishan Recreational Park (2000-2500 m), a few nests were taken under stones and in tree stumps at the forest edge and in glades in the forest, these were not particularly large and reminded us more of typical Myrmica ruginodis nests. Sexuals were observed leaving the nest (presumably to join a mating swarm - not seen) on 11th August 2002. (Radchenko and Elmes 2010)

Identification
A member of the rubra group. M. arisana female castes have frontal carinae that curve outwards and merge with the rugae, which surround the,antennal sockets, and its males have long antennal scape. On these characters it clearly belongs to the rubra species group and is not related Myrmica rugosa. Workers and queens differ from other species of this group by the distinctly prominent anterior clypeal margin; additionally, males well differ by the much coarser sculpture of the head dorsum, especially by the rugulose clypeus. (Radchenko and Elmes 2010)

Distribution based on Regional Taxon Lists
Oriental Region: Taiwan.

Nomenclature

 *  arisana. Myrmica rugosa var. arisana Wheeler, W.M. 1930a: 95 (w.) TAIWAN. Radchenko & Elmes, 2010: 93 (q.m.). Subspecies of rugosa: Weber, 1947: 462. Raised to species and senior synonym of tipuna: Elmes & Radchenko, 1998: 221. See also: Radchenko & Elmes, 2010: 92.
 * tipuna. Myrmica kurokii st. tipuna Santschi, 1937h: 367 (w.) TAIWAN. Junior synonym of arisana: Elmes & Radchenko, 1998: 222.

Worker
Differing from the typical form of the species from the Himalayas in being slightly more robust, with more pronounced mesoepinotal impression, somewhat longer epinotal spines and a smooth dorso-median area on the postpetiole. The gaster is yellowish piceous, the legs and antennae also somewhat paler than in the typical form.

Queen
Radchenko and Elmes (2010) - Resembles workers by the shape of the head and scape, but differ by having relatively shorter propodeal spines and longitudinally rugose scutum and scutellum, without reticulation.

Male
Radchenko and Elmes (2010) - Head slightly longer than broad, with widely rounded occipital corners, lateral and occipital margins convex, anterior clypeal margin narrowly rounded and prominent, without a medial notch. Scape long and very weakly curved at the base, antennae 13-segmented; second funicular segment about 1.5 times longer than the third one. Alitrunk relatively long, scutum slightly convex, scutellum does not project dorsally above scutum when seen in profile. Propodeum with short blunt denticles. Petiole relatively short, with almost straight and steep anterior surface and widely rounded node dorsum (seen in profile); postpetiole higher than long, with convex dorsum.

Head dorsum (including clypeus) with dense but not coarse longitudinal rugulae, surface between rugae densely though very finely punctated, but appears shiny. Scutum smooth or at most finely longitudinally striated posteriorly, central part of scutellum smooth and shiny, lateral parts with rugosity. Sides of pronotum very finely longitudinally striated and punctated, and mesopleura smooth, sides of propodeum rugose. Petiole and postpetiole smooth and shiny.

Head margins and mandibles with numerous, relatively long suberect hairs. Alitrunk, waist and gaster with numerous fine short hairs. Scape, tibiae and tarsi with quite dense subdecumbent to suberect pilosity. Body colour blackish-brown, appendages brownish.

Type Material
Radchenko and Elmes (2010) - "Five workers from Arisan". M. kotokui tipuna: "Formose: 4 w (K. Sato), (n° 727)".

Etymology
Radchenko and Elmes (2010) - named after the Arisan region of Taiwan where the type specimens were collected.