Otostigmus (Otostigmus) astenus, (Kohlrausch, 1881), 1903

Lewis, J. G. E., 2000, Variation in three centipede species of the genus Otostigmus and its bearing on species discrimination (Chilopoda; Scolopendromorpha; Scolopendridae), Journal of Natural History 34, pp. 433-448 : 438-441

Otostigmu s (O.) astenus (Kohlrausch, 1881)

(®gures 20±30)

Branchiotrema astenon Kohlrausch, 1881: 72

astenus: Kraepelin, 1903: 114 , ®gure 51

(O.) astenus: Attems, 1930:143 , ®gure 174

iagnosis Tergites marginate at least from 17, without keels, with or without spines; 17±21 antennomeres, the basal 2.5 glabrous dorsally. Sternites with complete paramedian

IGS 20±30. Otostigmus astenus ; (20) dorsal view of head, spm 1; (21) forcipular coxosternal toothplates, spm 1; (22) forcipular prefemoral process, spm 1; (23) posterior tergite, spm 1; (24) sternite 14, spm 1; (25) sternite 21, spm 30; (26) ventral view terminal segments and end leg prefemur, spm 1; (27) lateral view terminal segments, spm 28; (28) forcipular coxosternal toothplates, spm 23; (29) forcipular prefemoral process, spm 23; (30) forcipular coxosternal toothplates, spm 31. Scale line= 1 mm.

sutures and without tubercles. Last sternite narrowed or not. Coxopleural process a dorsal spine.

The specimens described here are conspeci®c and have been assigned to O. astenus

reasons discussed below.

Material examined

Rennell Island Galathea Expedition 1950±52 (ZMC). Spms 2, 3 and 16; 45, 39 16 mm, Stn no. L352, Lavanggu, 11ss39¾S, 160ss14¾E, 13 October 1951. Spm 22; mm, Lanvanggu, 15 October 1951. Spm 17; 32 mm, Stn no. L364, 11ss38¾S ss08¾E, 16 October 1951.

Rennell Island , Torben Wol leg 1965 ( ZMC). Spms 11 and 27±30; 22±55 mm, Hutuna, March 1965 .

Rennell Island , Noona Dan Expedition 1961±62 ( ZMC). Spm 1, 7, 8, 9 and 13; ± 32 mm, Niupani, 20 August 1962 .

New Britain, Noona Dan Expedition 1961±62 ( ZMC). Spms 23±26; 50, 48, 22 19 mm, Yalom , 35 km SE of Cape Lambert, 1000 m, 17 May 1962 . Spm 31; mm, the same, 19 May 1962. Spm 32; 42 mm Yalom , 21 May 1962 . Spm 33; mm, 10 May 1962. Spm 34 and 35; 32 and 37 mm, 8 and 24 May 1962.

Description of Rennell Island material

Maximum length 62 mm. Head capsule with large, widely separated puncti in larger specimens (®gure 20). Antennae with 19±21 antennomeres (17 in spm 16, length 16 mm). Of the 27 antennae examined, seven were damaged and 11 regenerated. The basal 2.25±2.3 glabrous dorsally (mostly 2.3) but two in spm 16.

Forcipular coxosternal teeth 4 +4 or 5 +5, there being three large teeth on each

, an outer separated by a deep incision from an inner two, in addition a small outer tooth in specimens with 4 +4 teeth. Specimens with ®ve teeth have in addition smaller inner tooth as in the right toothplate in ®gure 21, the left has, atypically,

teeth. Forcipular prefemoral process, usually with two lateral teeth (®gure 22) which may be low or absent.

Tergites with paramedian sutures complete from 5, 6, 8 or 9 (normally 5 or 6), marginate from 6, 7 or 8. Lateral longitudinal corrugations very poorly developed except in spm 30. Tergite keels absent but spines present in 10 specimens of

± 55 mm, from between segment 7±15 to 20 or 21 (®gure 23). Absent in ®ve of

± 32 mm. Last tergite with posterior median depression.

Paramedian sutures occupying the anterior quarter to one-third of anterior sternites, the anterior third to a half of the posterior ones (®gure 24), except in specimen 9 where they extend to two-thirds in the middle sternites. Pits present or absent. When present a posterior median pit and two lateral, one at the end of each paramedian suture. Sternite 21 with sides converging posteriorly and concave posterior edge (®gure 25) in small and medium-sized specimens (16±49 mm) but parallel-sided (®gure 26) in the larger (55±62 mm).

Coxopleural process moderately long with two (three) end spines, two to three lateral spines and one or two dorsal spines (®gure 27).

End legs: prefemur with (three) four (®ve) ventrolateral spines, (two) three or

ventromedial, two or three medial, two (three) dorsomedial and a corner spine.

Leg 1 with femoral spine, tibial spines present or absent on ®rst one, two, three

®ve pairs of legs. Two tarsal spines on ®rst 7±10 or 11 pairs of legs (atypically rst three only in specimen 9). One tarsal spine on rest of legs to leg 20 in four, to

21 in eight specimens.

Description of New Britain material

Maximum length 50 mm. Head capsule with large puncti in larger specimens. Antennomeres 20±21; 18 antennae were examined of which three were damaged and

regenerated. Regenerated antennae had up to 23 antennomeres. Basal 2.25±2.3 antennomeres glabrous. Atypically 2.6 in specimen 31.

Forcipular coxosternal teeth 4 +4 or 5 +5, except 7 + 7 in specimen 23 due to

presence of extra subsidiary teeth (®gure 28) but the basic arrangement of 4 +4

still apparent. In specimen 31 the inner teeth are worn down (®gure 30). The forcipular prefemoral process has one, two or three lateral teeth (®gure 29).

Tergites with paramedian sutures complete from 5, marginate from 7, 8 or 9, lateral corrugations poorly developed except in the two smallest specimens (25 and). Spines present on tergites of six of the nine specimens. Present or absent in

small and large specimens: three specimens of 17±46 mm without spines, six specimens of 24±56 mm with them. Tergite 21 with anterior median longitudinal ridge in specimens 24 and 31 in addition to posterior median depression.

Paramedian sutures occupy anterior two-thirds in posterior sternites in specimens

and 26 (21 and 19 mm). Sutures therefore longer in small specimens. Some specimens with single posterior median pit on sternite. Last sternite quadrate in largest specimens (23, 24, 31). Coxopleural process with two end spines, (one) two

three lateral spines, one dorsal spine in seven specimens, zero in one.

End legs: prefemur with (three) four (®ve) ventrolateral spines, two (three) ventromedials, two (three) medials, one or two dorsomedials and a corner spine.

Tibial spines on ®rst two to four or ®ve pairs of legs, two tarsal spines on ®rst

, six or seven, one on subsequent legs to 21 in six specimens, to 20 in one.

Remarks

The type material was redescribed by Kraepelin (1903). The specimens described above are very similar to it. Characters of type material (Rennell Island and New Britain material in parentheses) are: Antennomeres 18±20 (19±21). Coxosternal

3 +3, seldom 4 +4 (4 +4 or 5 +5). Sternite 21 quadrate or widening at end sides converging posteriorly or quadrate). Two tarsal spines on legs 4±12 (17) (two tarsal spines on ®rst (three) 5±10 or 11 pairs of legs). Leg 21 mostly without tarsal spine (with or without).