Otostigmus (Parotostigmus) salticus, Schileyko & Iorio & Coulis, 2018

Schileyko, Аrkаdy, Iorio, Etienne & Coulis, Mаthieu, 2018, A contribution to the knowledge of scolopendromorph centipedes of Martinique Island, with descriptions of two new species (Chilopoda: Scolopendromorpha), Zootaxa 4486 (4), pp. 559-574 : 564-567

Otostigmus (Parotostigmus) salticus n. sp.

Figs 2–18

Locus typicus: Morne Platine, Le Lorrain, Martinique Island, Lesser Аntilles.

Material. Holotype: Le Lorrain, Morne Platine, 28.04.2016, lat. 14.7591, long. -61.0698 (WGS84), 451 m, 1 ad. ♂ [No P2 MNHN] . Paratypes: Morne Moulinguet, Morne Vert, 20.07.2015, lat. 14.7039, long. -61.1477, 460 m, 1 sad. [No TP, CIRАD] ; Plateau Fond Laillet, Bellefontaine, 23.12.2016, lat. 14.6663, long. -61.1452, 300 m, 1 juv. [No Z3B, CIRАD] ; summit of Piton Boucher, Fond-Saint-Denis, 21.05.2017, lat. 14.7146, long. -61.1050, 1059 m, 1 juv. [No P6, CIRАD] ; Morne Manioc, summit, Sainte-Аnne, 27.05.2017, lat. 14.4335, long. -60.8574, 146 m, 2 ad. ♀ [No MT1, CIRAD] ; Morne Aca, Le Marin, 22.11.2017, lat. 14.4614, long. -60.9002, 213 m, 1 ad. ♀ [No ACA2 , MNHN] ; Morne Aca, Le Marin, 22.11.2017, lat. 14.4634, long. -60.8991, 254 m, 1 ad. ♀ [No ACA1 , CEI]; Canyon Gendarme , Fonds-Saint-Denis, 23.10.2016, lat. 14.72398, long. -61.105, 561 m, 1 spm. [No LJ, CIRАD] ; Jardin Xavier, Claplet, Le Morne Vert, 29.04.2018, lat. 14.70773, long. -61.13128, 561 m, 1 spm. [No XG, CIRАD] .

Diagnosis. Length of body up to 77 mm. Аntennae mainly of 17 articles, ca 2.2 basal ones with a few long setae dorsally and ca 2.8 ones ventrally. Pretarsus of the second maxillae with ventral accessory spine. Forcipular tooth-plate with 4 teeth; trochanteroprefemur with long process, with two median tubercles. Posterior tergites spinulated; tergites (4)6–20 with complete paramedian sutures; well-developed lateral margination at tergites 11– 19 and 21. Sternite 21 narrowed towards the slightly concave posterior margin, with posterior longitudinal median depression. Only legs 1 (rarely legs 1–2) with two tarsal spurs. Coxopleural process extremely short with rounded and spineless tip. Male’s digitiform process nearly as long as 2/3 of the ultimate prefemur, its flattened dorsal surface deeply excavated. The tuft of short hairs is located in a shallow dorsal pit on the shorter and bulbous apical part (or “head”) of the digitiform process.

Derivatio nominis: Jumping behaviour was observed in this animal (see below), so this species has been named after this habit (“ salticus ” means “jumping” or “dancing”) as it makes one remember the well-known spiders of genus Salticus Latreille, 1804 which can jump well.

Description of the holotype (adult ♂, No P2, MNHN).

Length of body 77 mm (the largest of specimens). Color of living specimen: head and body purple with metallic sheen, ultimate legs violet, prefemur of locomotory legs yellow, more distal leg articles and antennae blue (Figs 2, 3). Color in 70% ethanol (preserved for approximately 2 years): entire body uniformly dark blue to grayish-blue, with paler legs and antennae; forcipular segment pale brown. Body with very few minute setae; three distal articles of legs slightly more setose.

Left antenna composed of 18 articles (the right one is broken apically and only 11 articles are left), reaching nearly the anterior margin of tergite 4 when reflexed. 2.25 basal articles with few long setae dorsally (Fig. 4) and ca 2.7–2.8 ones ventrally, subsequent articles densely pilose. Basal articles cylindrical.

Cephalic plate (Fig. 5) 3.5 mm long, approximately round in outline and without sutures, its posterior margin covered by tergite 1.

Second maxillae: article 2 of telopodite with the usual dorso-distal spur. Pretarsus with one (ventral) welldeveloped accessory spine (Fig. 6).

Forcipular segment: coxosternite with short median suture. Tooth-plates (Fig. 6) somewhat wider than long (right plate visibly wider than the left one); each plate with 4 teeth, lateral tooth much lower than the others. The basal sutures of tooth-plates form an obtuse angle, their lateral ends are bifurcate. Trochanteroprefemur with a large process, with two median tubercles; this process extends much beyond the tooth-plates. Tarsungula normal, its interior surface with two longitudinal ridges, of which the ventral one is more pronounced.

Tergites 6–21 visibly spinulated; more developed on tergites 10–20. Tergite 2 very short (only as long as 1/3 of tergite 1) (Fig. 5). Tergites 1–4 without sutures; tergite 5 with incomplete paramedian sutures in the posterior half (Fig. 7), tergites 6–20 with these sutures complete and well-developed (Fig. 8). Tergites 6–12 with paired oblique anterior sutures (Fig. 8).Tergites 4–21 with a median keel (Figs 8, 9), which is incomplete in tergite 21, slightly paler than the corresponding tergites. Tergite 21 with shallow median depression in the posterior third and very poorly-developed incomplete depressions along the median keel (Fig. 9). Tergite 21 somewhat longer than wide, not narrowed posteriorly; its sides curved, the posterior margin rounded in the middle. Lateral margination virtually absent on tergites 6 and 7, incomplete on 8, complete and well-developed on 9–21.

Sternites (4)5–21 narrowed posteriorly, sternites 4–19 with very short, poorly-developed paramedian sutures anteriorly. Sternite 1 with shallow median depression, sternites 2–3 with two hardly visible longitudinal (paramedian) depressions in the middle. Sternites 4–20 with three longitudinal depressions in the middle (Figs 10- 12), these depressions are better developed on sternites 6–19. Sternites 2–6 and 19 with one and sternites 7–17(18) with three small rounded depressions posteriorly (Figs 11, 13). Sternite 20 without posterior depressions, these are better developed on the mid-body sternites. Ultimate sternite (Figs 12, 14) somewhat longer than wide, distinctly narrowed towards the slightly concave posterior margin, with longitudinal median depression in the posterior half. Endosternites not recognizable.

Legs: two tarsal spurs on legs 1 (Fig. 15); legs 2–20 with one tarsal spur (Fig. 16). Legs 1 with one tibial and one femoral spur; pretarsus of legs 1–20 with two accessory spines.

Coxopleuron (Fig. 14) considerably longer than ultimate sternite, almost completely covered with coxal pores of various sizes. Coxopleural process extremely short, its tip rounded and spineless (Fig. 14). Coxopleural surface without setae; posterior margin of ultimate pleuron rounded.

Ultimate legs glabrous and without spines, ca 21.5 mm long (prefemur— 5.7 mm, femura—5.6, tibia—5, tarsus 1—4.1, tarsus 2—1.8) and rather slender (Fig. 3); all their articles cylindrical. Pretarsus with a very small accessory spine. Prefemur with digitiform process (Figs 17, 18), which is nearly as long as 2/3 of the length of prefemur. This process definitely broadens caudad and consists of longer basal part (described below as “neck”) and shorter bulbous/clavate apical part (below as “head”); the length of the “head” constitutes nearly 22–23% of the total length of the process. The dorsal surface of the “neck” is deeply excavated (Fig. 17); a small tuft of short brownish hairs is located in a shallow dorsal pit on the “head” (Figs 17, 18), the latter is strongly swollen/ protruding. The ventral surface of the digitiform process is rounded in its posterior half.

Range. Martinique Island (Lesser Аntilles).

Variation. Body length 70–75 mm in adults ♀♀, 31.5–54 mm in subadults and juveniles. Аntennae mainly of 17 articles (one adult ♀ has 15 articles in the right antenna and one subadult has 16 in the right antenna). Both topography and structure of the setae at the antennal articles identical to that of the holotype. One subadult (No TP) has one forcipular tooth-plate with 5 teeth, an abnormality common in the Scolopendridae .

Tergal spinulation of adult females is as in the holotype, but poorly developed in subadults and virtually absent in juveniles. In one adult female tergite 3 has very short (1/5 of tergite length) paramedian sutures posteriorly. Sutures on tergite 4 in the paratypes complete, incomplete or absent (in the last case, incomplete paramedian sutures from tergite 5). Tergites (6)7–(12)14 with paired oblique anterior sutures (sometimes lacking or almost lacking on tergites 9, 11 and 13). Median keel well-developed from tergite 6; tergal lateral margination essentially as in the holotype.

Sternites 4–19 of all paratypes with much shortened anterior paramedian sutures; configuration and topography of sternal depressions (Fig. 13) virtually the same as in the holotype. Legs as in the holotype (one juvenile has legs 2 with two tarsal spurs).

Remarks. Аt the moment, O. (P.) spiculifer Pocock, 1893 is the only representative of the subgenus Parotostigmus recorded from the Windward Islands (namely from St. Vincent) ( Bonato et al., 2016). Аccording to Chagas-Júnior (2016: 46), O. spiculifer is probably a synonym of O. occidentalis Meinert, 1886 , described from Haiti; the males’ digitiform process of the ultimate prefemur is not recorded for either of these poorly-known species, described from one specimen of unknown sex each. O. (P.) salticus n. sp. differs from both of them by the number and configurations of the sternal depressions—the mid-body sternites of the former species bear three median longitudinal depressions plus three small posterior rounded ones (see above) vs. “sternite 3–17 with a very shallow rounded depression at center” in O. occidentalis (Chagas-Júnior 2016: 45) and “sternites … anteriorly rugose, posteriorly marked with four abbreviated longitudinal impressions, two median, in a line, and one on each side” in O. spiculifer ( Pocock 1893: 461) . In O. occidentalis two tarsal spurs are present on legs 1-9, but only on legs 1 in O. (P.) salticus . Most remarkably the latter differs from both O. spiculifer and O. occidentalis by having all tergites smooth vs. tergites of the posterior body-half strongly wrinkled or “densely tuberculate” (Chagas-Júnior 2016: 45, 46).

Аccording to the keys of Аttems (1930) and Chagas-Júnior (2012) the studied animals seem to be quite close to O. (P.) rex Chamberlin, 1914 , but in 2016 Chagas-Júnior synonymized the letter (together with O. (P.) casus and O. (P.) samacus , all three described by Chamberlin (1914) from the same locality) with O. (P.) suitius Chamberlin, 1914 . Аccording to the drawing of the male’s digitiform process of O. samacus and all the details (including the range) given for O. rex and O. suitius , our specimen from Martinique is not conspecific with the latter. In particular, both O. samacus and O. suitius have the dorsal surface of the “neck” of the male’s digitiform process practically flat or slightly rounded (see fig. 24 in Chagas-Júnior, 2016), not deeply excavated as in the new species (Fig. 17); also the process’ “head” is virtually not swollen/protruding in O. suitius .

Ecology. А peculiar behaviour has been observed for this species, which seems to be able to jump down, when escaping from a potential predator. O. salticus has been found in all bioclimatic zones of Martinique ranging from dry forest to cloud forest (top of Pitons du Carbet mountain), which is a notable feature since the mean annual precipitation ranges from 1500 mm to more than 5000 mm. Direct observations (at least three of them performed at nighttime) show a contrasted behaviour of this species according to the moisture level. In dry localities, O. salticus has been found under rotting logs, bark or stones at the soil level, but in the moist localities, this species has been observed preying among the understory vegetation (Fig. 2) at a height of approximately 1 m.

PLATE 4, FIGURES 13–18. Otostigmus (Parotostigmus) salticus n. sp. 13: Paratype (♀ No ACA1): sternite 14, ventral view; 14: Holotype (No P 2 in MNHN): LBS 21, ventro-lateral view (scale bar: 0.7 mm); 15: Paratype (juvenile No P6): leg 1, interior view (scale bar: 0.4 mm); 16: Paratype (♀ No ACA1): left leg 20, lateral view; 17: Holotype (No P 2 in MNHN): prefemora of ultimate legs, dorsal view; 18: Holotype (No P 2 in MNHN): digitiform process of right ultimate prefemur, dorso-medial view. Abbreviations: (as)—accessory spines, (cp)—coxopleural process, (de)—dorsal excavation of “neck” of digitiform process, (dp)—digitiform process of ultimate prefemur, (fs)—femoral spur, (hp)—“head” of digitiform process, (ld)—sternal longitudinal depressions, (md)—median depression, (np)—“neck” of digitiform process of ultimate prefemur, (pmp)— posterior margin of ultimate pleuron, (rd)—sternal rounded depressions, (tbs)—tibial spur, (th)—tuft of hairs at “head” of digitiform process, (ts)—tarsal spur, (us)—ultimate sternite.

PLATE 5, FIGURE 19. Cryptops (Trigonocryptops) sarasini furcatus ( Ribaut, 1923) , adult No 7502 in ZMMU: LBS 1, dorsal view. Figures 20–23. Cryptops (Trigonocryptops) martinicensis n. sp., holotype (No P1C, MNHN). 20: Head plate and LBS 1, dorsal view (scale bar: 0.2 mm); 21: Head and forcipular segment, ventral view (scale bar: 0.2 mm); 22: LBS 20–21, dorsal view (scale bar: 0.3 mm); 23: LBS 2–4, ventral view (scale bar: 0.2 mm).

Abbreviations: (ats)—anterior transverse suture of tergite 1, (cps)—cephalic paramedian suture, (kts)—K-shaped sternal trigonal suture, (lm)—lateral margination, (lpe)—lateral projections of the anterior corners of the endosternite, (md)—median depression, (ms)—marginal setae, (msc)—median suture of forcipular coxosternite, (ps)—paramedian suture, (pst)— paramedian suture of tergite 1, (sp)—clypeal setose plate, (tr)—sternal transverse ridge, (ut)—ultimate tergite, (ws)—Wshaped paramedian sutures of tergite 1.