Otostigmus seychellarum Attems, 1900

Lewis, John G. E., 2014, A review of the orientalis group of the Otostigmus subgenus Otostigmus Porat, 1876 (Chilopoda: Scolopendromorpha: Scolopendridae), Zootaxa 3889 (3), pp. 388-413 : 406-407

Otostigmus seychellarum Attems, 1900 (reinstated)

(Fig. 54)

Otostigma seychellarum Attems, 1900 , 136. Seychelles.

Nec Otostigma carinatum var. insulare, Haase, 1887: 69 . Java, Ceylon [ Sri Lanka] Nec Otostigma insularis Haase, 1887 : Kraepelin, 1903, 112.

O. (O.) insularis: Attems, 1930 , 154. Ceylon [ Sri Lanka], Seychelles (In part). O. (O). orientalis : Lewis, 2007, 12, Fig. 5–10. Seychelles.

O. (O). orientalis : Lewis, 2010b, 389, Figs 7, 8.

Diagnosis. (Lewis’s (2007) material of Seychelles ‘ O. orientalis’). Length 14–35 mm. Antennal articles 17, the basal 2.1–2.5 (atypically 3) glabrous dorsally. Forcipular coxosternal teeth 4+4. Tergites with complete paramedian sutures beginning between 6 and 9, margination beginning from between 3 and 7. Mostly with seven keels with fine spinules from T5, 6 or 7. The keels may be sharp or rounded and, atypically, absent. Sternites with very short anterior paramedian sutures, with up to five weak depressions. Sternite of ultimate leg-bearing segment, with rounded sides converging posteriorly, the posterior margin usually rounded (Fig. 54) or sometimes slightly concave. Ratio of length to width 0.7:1 to 1:1. Coxopleural process with two apical and one lateral spine. Leg 1 with one or two tarsal spurs, 2–19 or 20 with a single tarsal spur, 21 without. Ultimate leg prefemoral spines: VL 2–3, VM 2, M 0, DM 0, CS 0, i.e. only two spine rows.

Remarks. Kraepelin (1903) synonymised O. seychellarum under O. insularis Haase, 1887 . Subsequently Chao & Chang (2003) synonymised O. insularis under O. scaber Porat, 1876 . However, Lewis (2007) noted that Attems’ O. seychellarum was clearly not O. scaber . He stated that it was a junior synonym of O. orientalis but later ( Lewis 2010b) suggested that the differences between the Indian and Seychelles populations may be a case of geographical variation within the species, or it may be that there are two closely related species, the larger in India and the smaller in the Seychelles.

The Indian and Seychelles populations hitherto assigned to O. orientalis show a number of striking similarities, namely: 17 antennal articles, forcipular coxosternal teeth 4+4, sternites with very short anterior paramedian sutures, coxopleural process with two apical and one lateral spine only, ultimate leg prefemur typically with VL 3, VL 2, DM 0 or 1 spines.

The populations differ in that the Indian specimens appear to be larger, having a size range 36–65 mm as opposed to 14–39 mm in Seychelles material, and tergites with keels and fine spinules in the majority of the Seychelles specimens. The sternite of the ultimate leg-bearing segment is generally more elongated in Indian specimens with a concave posterior margin, generally rounded in the Seychelles material. Indian specimens have two tarsal spurs on the first 3, 4 or 5 pairs of legs as opposed to only on leg 1 or none in the Seychelles specimens.

Other possible differences are earlier commencement of tergite paramedian sutures in Indian specimens (5, 6 or 7 as opposed to 6 to 9) and the later commencement of margination (commencing on 6–8 as opposed to 3–7). Further sampling is required to confirm these differences.

I now consider that these differences are sufficient to merit specific status and here reinstate Attems’ O. seychellarum .

Pocock (1891) recorded similar variation to that seen in O. seychellarum in O. carinatum Porat, 1876 (= O. scaber ) from many localities in Burma. He described it as having tergites “either slightly wrinkled and sparsely spicular, or strongly carinate and subserially spicular.” Those specimens of O. seychellarum with sharp tergite keels run down to the scaber group in Lewis (2010a).