Ponera loi

Ponera loi is known only from forested areas near Afiamalu. According to Zimmerman (pers. comm.), his specimens were taken in undisturbed forest, at roadsides or along native trails. The Taylor and Ettershank material is from the disturbed forest. P. loi is evidently a rather rare species and appears, from the Taylor and Ettershank collections, to be much less abundant at Afiamalu than the similar and sympatric Ponera woodwardi. In intensive collecting there I took it only once, although it may have been overlooked at times, due to my confusing it with the common woodwardi, which was not always collected. (Taylor 1967)

Identification
Taylor (1967) - Similar to the New Guinean Ponera syscena, particularly in having a relatively narrow petiole node (petiolar node index 78-82). This character allows immediate separation of syscena and loi from the other members of the japonica species group, whose PNI's range from 84-91.

Workers of P. loi are easily distinguished from the sympatric Ponera woodwardi by differences in scape index (84-91 in loi, 98-102 in woodwardi). The other sympatric species on Samoa (Ponera incerta, Ponera swezeyi and Ponera tenuis) are all considerably smaller.

Key to Micronesian Ants

Distribution
Known only from the Samoan island of Upolu.

Distribution based on Regional Taxon Lists
Indo-Australian Region: Guam, Marshall Islands, Northern Mariana Islands, Samoa.

Biology
Little is known about the biology of Ponera loi.

Nomenclature

 *  loi. Ponera loi Taylor, 1967a: 60, figs. 52-55 (w.q.) SAMOA.

Worker
(Based on the holotype and 8 paratypes collected at Afiamalu by Zimmerman in 1940 and by Ettershank and me in 1962). Dimensions (holotype cited first): HL 0.66 mm, 0.62-0.70 mm; HW 0.53 mm, 0.51-0.58 mm; SL 0.46 mm, 0.44-0.52 mm; CI 80, 79-83; SI 87, 84-91, PW 0.40 mm, 0.37-0.42 mm; PNL 0.21 mm, 0.20-0.23 mm; PH 0.41 mm, 0.39-0.44 mm; DPW 0.33 mm, 0.30-0.34 mm; PNI 82, 78-81. With the characters of the japonica species group. Close to Ponera syscena in the details of mandibular, clypeal, and antennal structure, and in color, sculpturation, pubescence and pilosity. The loi types differ from the available syscena material in the following characters:

1. Head length 0.62-0.70 mm as opposed to 0.60-0.62 mm in syscena. The frequency distribution of HL measurements in loi is strongly skewed toward the high values. The mean HL values of the 2 species are: loi 0.66 mm (N=9); syscena 0.61 mm (N=7).

2. Head width 0.51-0.58 mm, opposed to 0.48-0.51 mm in syscena. The mean values again give more conclusive separation-in loi the mean HW is 0.54 mm (N=9); in syscena it is 0.49 mm (N=7).

3. The head of P. loi is proportionately larger relative to the body than that of syscena. In the former the head width ranges from 1.31 to 1.38 x the pronotal width, while in the latter, values of 1.23-1.28 X are yielded.

4. Median clypeal denticle distinctly developed in loi, vestigial in syscena.

5. The outline of the mesosomal dorsum in loi (fig. 53) is slightly indented at the mesometanotal suture, where it is straight and uninterrupted in syscena. The mesometanotal suture of loi, unlike that of syscena, is represented by a fairly marked transverse impression, which is accompanied by a fine and indistinct incised sutural trace in some specimens.

Queen
3 dealate paratypes collected by Swezey and Zimmerman in 1940 have the following dimensions: HL 0.71-0.73 mm; HW 0.60-0.63 mm; SL 0.50-0.55 mm; CI 85-86; SI 83-87; PW 0.50-0.53 mm; PNL 0.21-0.23 mm; PH 0.46-0.50 mm; DPW 0.38-0.40 mm; PNI 75-76; maximum diameter of eye 0.20; ocular index 32-33. Conforming to the general plan of queen structure for the genus, and differing from the workers in the usual characters of full sexuality. Medium clypeal denticle distinctly developed, as in the worker, and the apices of the scapes are almost exactly contiguous with the median occipital border.

Females of loi are distinguished from related species by the same characters differentiating the workers. The unique known Ponera colaensis queen is smaller, with a proportionately wide petiolar node (HW 0.54 mm; PNI 82), and woodwardi queens have narrower heads and longer scapes (CI 80-84; SI 99-102).

Type Material
Holotype and paratypes (worker and queen) in collection. Paratypes in, , , Forel Coll. and.