Otostigmus ( O .) trisulcatus Verhoeff, 1937

Lewis, John G. E., 2015, On Verhoeff’s Otostigmus subgenus Malaccopleurus, the nudus group of Otostigmus subgenus Otostigmus Porat, 1876, and Digitipes Attems, 1930, with a description of the foetus stadium larva in O. sulcipes Verhoeff, 1937, (Chilopoda: Scolopendromorpha: Scolopendridae), Zootaxa 4039 (2), pp. 225-248 : 229-232

Otostigmus ( O.) trisulcatus Verhoeff, 1937

( Figs 17–22)

Otostigmus (Malaccopleurus) trisulcatus Verhoeff, 1937 , 204 (key), 207, Pl. 12, Fig. 7 . Kuala Legap, Plus Valley, Perak and Kuala Terla, Telom Valley, Pahang, 1500 m. Malacca [ Melaka, Peninsular Malaysia].

Type material examined. ZMB 13365 syntype. O. trisulcatus Malacca (one vial and 2 slides, 4002 & 4003). In vial: Otostigmus trisulcatus Malacca Verh. 2015. Slides: Perak, Malacca Syntypus ZMB 13365 , 4002 (segments 18–21) & 4003 (head, antennae, mandibles and segments 1–5).

Description of syntype in ethanol. (Verhoeff’s data in parentheses where relevant). (A slender species similar in most characters with sulcipes ). Length approximately 36 mm (46–47 mm). Colour greyish orange (yellow with green stripes). (Distinguished by its thinness from all other Otostigminae).

Antennal articles 18+18, the basal three glabrous dorsally. Forcipular coxosternal tooth-plates atypically with two on the right, three teeth with a trace of a median fourth on the left ( Fig. 17). Other specimens have 4+4 teeth, see below. Forcipular trochanteroprefemoral process without or with one medial denticle ( Fig. 18).

Tergites with compete paramedian sutures from 5, marginate from 9, (21 only!) weak lateral corrugations also from 9, a very weak median keel on posterior tergites. Tergite of ultimate leg-bearing segment with weak longitudinal posterior median depression.

Sternites with complete paramedian sutures in deep sulci and a median longitudinal depression but without small round posterior median depression ( Fig. 19). Sternite of ultimate leg-bearing segment with sides converging posteriorly and posterior margin very slightly curved ( Fig. 20). Coxopleural process digitiform with two apical spines, the pore-field narrow.

Legs without tarsal spurs. Ultimate legs slender, the prefemoral spines small, VL 3, VM 2, M 2 or 3, DM 2, CS 1, the prefemur, femur and tibia with a low median longitudinal dorsal ridge demarcated by shallow grooves, the prefemur with faint pitting ( Fig. 22) (the prefemur has only very weak pits and traces of grooves).

Description of syntype on slides 4402 & 4003. Antennal articles 18+18, the basal three glabrous dorsally, the first sparsely, the second moderately and the third densely setose ventrally. Forcipular coxosternal tooth-plates with 4+4 teeth, trochanteroprefemoral process without a median denticle.

Sternite of ultimate leg-bearing segment with sides converging posteriorly, the posterior margin rounded. Coxopleural process digitiform with two apical spines, pore-field narrow, not expanded anteriorly ( Fig. 21). Leg 1 with one tarsal spur, 2–5 and 18–21 without spurs. Ultimate leg prefemora with 15 and 16 spines in irregular rows, presumably regenerated.

Other material examined. ZSM. Two slides labelled Malaccopleurus trisulcatus Verh. Adol. 1, 2, Malacca and Malaccopleurus trisulcatus Verh. Adol. 19–21. Malacca. (The numbers 1, 2 and 19–21 refer to the segments on the slides).The invoice gives: Malaccopleurus trisulcatus Verhoeff types? (non reg.). The specimen is an early post-larval (adolescens) stadium.

Description. Length not recorded by Verhoeff. Antennal articles 18+18, the basal 2.5 glabrous dorsally and two ventrally. Second maxillary pretarsus with one (possibly two) accessory spines. Article 2 of telopodite with a spur on the right but not on the left. Forcipular coxosternal tooth-plates with 4 +4 teeth, each with a post dental seta and five or six other prominent setae. Forcipular trochanteroprefemoral process with one medial denticle.

Only the tergite of the ultimate leg-bearing segment marginate. Sternite of ultimate leg-bearing segment with posterior margin slightly concave. Coxopleural process of moderate length, with two apical spines, pore-field narrow, about three pores wide.

Legs 1 and 2 with a tarsal spur, 19–21 without. Ultimate leg prefemoral spines VL 3, VM 2, M3 or 4, DM 2, CS 1.

Remarks. Verhoeff (1937: 204) distinguished the two species in his key as follows:

Sternite of ultimate leg-bearing segment with concave posterior margin. Ultimate legs robust, with dorsal longitudinal grooves (Längsfurchen). Prefemur a little more than twice as long as wide. Trochanteroprefemoral process of forcipule extending beyond the trochanteroprefemur............................................................... sulcipes n. sp. Sternite of ultimate leg-bearing segment with rounded posterior margin, Ultimate legs slender, without longitudinal grooves, (but on p. 207 he stated that the prefemur had only very weak pits and only traces of grooves), prefemur more than three times as long as wide. Trochanteroprefemoral process of forcipule not extending beyond the trochanteroprefemur.. trisulcatus n.sp.

The proportions of the ultimate legs in O. sulcipes are based on the distorted material on a slide. They are, in fact, slender in the specimens in ethanol in both species. The statement that the trochanteroprefemoral process in O. trisulcatus does not extend beyond the trochanteroprefemur is also based on a distorted slide preparation. Verhoeff noted that O. trisulcatus could be distinguished from all other Otostigmus species by its thinness but O. sulcipes is of a similar shape. The differences in the shape of the sternite of the ultimate leg-bearing segment may not be significant: the posterior margin is curved in the larger specimens but concave in adolescens of O. trisulcatus .

The differences between these two putative species in respect to the development of the grooves and ridge on the prefemur, femur and tibia of the ultimate legs are a matter of degree and may be a sexual character, or subject to individual variation or developmental stadium. I regard O. trisulcatus as a junior subjective synonym of O. sulcipes , O. sulcipes having page priority. The two are compared in Table 1 .

Figures

FIGURES 1 – 8. Otostigmus sulcipes. 1. Forcipular coxopleural tooth-plates and left forcipular trochanteroprefemoral process, syntype ZMB 13364 Malacca, spm. in ethanol. 2. Sternite 11, the same. 3. Coxopleuron and sternite of ultimate leg-bearing segment, the same, ventral view. 4. Left ultimate leg prefemur and femur dorsal, the same. 5. Antennal article 3, syntype ZMB 13364, slide 3614, dorsal view. 6. Antennal articles 1 to 3, the same, ventral view. 7. Coxopleuron and sternite of ultimate legbearing segment syntype ZMB 13364, slide 3613, ventral view. 8. Ultimate leg prefemur, the same, ventral view. Scale bars = 1 mm except Figs 1, 3, 5 & 6 = 0.5 mm.

Tables

TABLE 1. Comparison of morphological characters of the putative species of Verhoeff’s subgenus Malaccopleurus and Otostigmus geophilinus. Significant differentiating characters in bold.

	O. sulcipes	O. trisulcatus	O. sutteri	O. geophilinus
	Peninsular Malaysia	Peninsular Malaysia	East Sumba	Myanmar, Java, Timor
Maximum length (mm)	43	47	30	45
Antennal articles	18	18	18	18
Basal articles glabrous	3	3	3	3 or 4 (5)
Forcipular coxosternal tooth plates	Longer than wide	Longer than wide	Longer than wide	Longer than wide
Teeth on coxosternal tooth- plates	4+4	4+4	3+4	4+4
Complete tergite paramedian sutures from	5	5	3	4 or 5
Tergites marginate from	7 or 8	9	13 or 14	Between 7 and 16
Sternite paramedian sutures/sulci	More or less complete	More or less complete	More or less complete	More or less complete
Sternite longitudinal depressions	One median	One median	One median	One median
Sternite posterior round depressions	One median	None	One median	One median or none
Coxopleural process spines	2 apical	2 apical	2 apical	2 apical
Coxopleural pore-field widened anteriorly	No	No	No	No
Legs with tarsal spurs	leg 1	leg 1 or 1 & 2	3–20	1–19
Ultimate leg dorsal grooves	On prefemur, femur and tibia	On prefemur, femur and tibia. Weak	On femur and tibia. Very weak	Present on prefemur, femur and tibia or absent
Ultimate leg prefemoral spine rows	4	4	4	4
Number of spines	11	10–12	11	9–11(14)