Scolopendra alternans Leach 1816
Creators: name: Schileyko, Arkady
name: Iorio, Etienne
name: Coulis, Mathieu
Publisher: name: Zenodo
Year: 2024
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Chilopoda
Scolopendromorpha
Scolopendridae
Scolopendra
Scolopendra alternans

description: Scolopendra alternans Leach, 1816
Figs 1–6
Locus typicus: British Virgin Islands, Tortola, Fat Hog’s Bay.
Recent material from Martinique. Absent.
Additional material. Cuba, 2 ad. (ZMMU, Rc 6323, 6324).
Description (of adult ZMMU, Rc 6324).
Species of stout proportions (Fig. 1) with relatively short ultimate legs, body length ca 102 mm.
Antenna of 17–18 articles, of them 5 basal ones with dense delicate and short setae which are transparent (so these articles looking glabrous); the following articles with longitudinal rows of darker setae which are well visible. Cephalic plate (Fig. 2) with complete paramedian sutures, slightly diverging cephalad, and a kind of branching transverse suture crossing the most posterior ends of the paramedian sutures.
Second maxillae: dorsal brush well-developed, pretarsus with 2 accessory spines.
Forcipular segment (Fig. 3): anterior third of the coxosternite with incomplete median suture, which meets complete transverse suture; chitin-lines absent. Tooth-plates slightly longer than wide; tooth-plate with virtually solid tooth-margin (teeth are fused) lacking separate teeth. A single short strong seta in a small rounded depression just below tooth-margin. Basal sutures of the tooth-plates form an obtuse angle (ca 100–110°). Trochanteroprefemur with large process (Fig. 3), which has no well-separated tubercles; process slightly longer than a tooth-plate. Tarsungula of normal length, its interior surface with a single sharp longitudinal ridge.
Tergites: anterior margin of tergite 1 covered by cephalic plate. Anterior third of tergite 1 with a characteristic pattern composed of fine transverse sutures (Fig. 2). These sutures, widely anastomosing, meet the anterior ends of the paramedian sutures and are practically not developed between the latter; paramedian sutures bifurcate widely cephalad (Fig. 2). Tergites 2–20 with complete paramedian sutures (Fig. 2); tergites 5–17 with oblique sutures. Tergites from the 7 th with indefinite and incomplete later margination, from the13th—with complete lateral margination.
Sternites 3–20 with complete paramedian sutures (Fig. 4).
Leg 1 with two and legs 2–(18)19 (Fig. 4) with one tarsal spur; pretarsus of legs 1–21 with two accessory spines. Prefemur of legs 19 with rudimentary and of leg 20 with well-developed corner spine which bear 2 and 4–5 apical spines respectively (Figs 5, 6).
Ultimate LBS: tergite 21 (Fig. 5) lacks sutures, definitely wider than long; sternite 21 (Fig. 4) much narrower than penultimate, longer than wide and distinctly narrowed towards slightly convex posterior margin. Coxopleuron (excluding coxopleural process) approximately 1.5 times as long as sternite 21, it is densely and virtually completely (i.e. with no posterior poreless area) covered with very small pores of various sizes. Short, cylindrical coxopleural process (Fig. 4) is poreless, with 3–4 apical plus 2–4 subapical spines; a single spine present at posterior margin of coxopleuron.
Ultimate legs (Fig. 6) stout (length of prefemur 7, width of prefemur 2 mm). Prefemur definitely and femur slightly flattened dorsally, other articles cylindrical. Prefemur with 10–12 (three rows) ventral, 10–12 (three rows) ventro-medial plus medial and 5–6 (two rows) dorso-medial spines; corner spine (Figs 5, 6) stout, with 8 apical spines. Pretarsus long (somewhat shorter than tarsus 2) with two small but well-developed accessory spines.
Range (after Chamberlin 1950: 135 and Shelley 2002: 36, much corrected). Florida Peninsula; Bahamas; Greater Antilles: Cuba, Hispaniola, Puerto Rico; Lesser Antilles: US Virgin Islands (St Thomas, St John, St Croix), Antigua, Barbuda, St Barts, St Eustatius, St Kitts, Antigua, Montserrat, Guadeloupe, Martinique (?), Dominica, St. Lucia; Northern part of South America: Venezuela, Brazil. Occasional samplings in Canada (Quebec, Montreal) and USA (NY; Pennsylvania; District of Columbia; Georgia).
Remarks. Mercurio (2016) split S. alternans, resurrecting S. longipes Wood, 1862, and S. cubensis Saussure, 1860, from its junior synonyms based on some variability in both length and coloration of the body plus insignificant differences in spination of the basal articles of the ultimate legs and coxopleural process. However, all these points fit well within the borders of intraspecific variability of any such widespread Scolopendra species as S. alternans. Thus, we agree with Chagas-Jr & Galvis Jiménez (2018) who discussed the relationships of S. alternans, S. armata Kraepelin, 1903 and S. arthrorhabdoides Ribaut, 1913 and reject the Mercurio’s (2016) split mentioned above. Summing up we also prefer to keep the traditional concept of S. alternans as a quite widespread but a single species.
We also like to clarify the situation with the “absence of anterior transverse suture of tergite 1” in S. alternans as certain confusion may result from this one of the main diagnostic characters of this species. The original description does not contain information about any tergal sutures, so practically all recent authors repeated the corresponding data of Pocock (1893: 459). This author presented only a short key for the West Indian species of Scolopendra (five species), writing about S. alternans (couplet b.): “The first tergite not marked anteriorly with a sulcus…”, but gave neither descriptions nor drawings for any species. Thus, he seems to be the first who used this character to divide the genus Scolopendra into two corresponding groups. This information was uncritically repeated by Kraepelin (1903), Ribaut (1913), Attems (1930), Lewis (1989), Shelley (2002), Mercurio (2016) etc who state the absence of this structure in S. alternans (and in a few close related species). Chagas-Jr & Galvis Jiménez (2018) were the first to note (page 162, table 1) that tergite 1 of S. alternans has “Anastomosing sutures and paramedian sutures” and showed quite a similar pattern in S. arthrorhabdoides Ribaut, 1913 (compare corresponding figure 16 and Fig. 2).
In fact, tergite 1 of S. alternans bears a characteristic pattern in the form of numerous thin (but well developed) transverse sutures, anastomosing with each other and with the anterior ends of the paramedian sutures (Fig. 2) and not similar to the ordinary “anterior transverse suture” of tergite 1. However, part of this pattern can be interpreted as a kind of (incomplete) transverse suture of tergite 1, so it should not be said that this suture is completely absent in S. alternans (and the closely related S. arthrorhabdoides). We believe that to clarify this issue it is necessary to analyze in detail the nature of the usual transverse suture, as well as these thin anastomosing sutures of tergite 1 (and the so-called “anterior complex”; see data on S. viridicornis and Scolopocryptops miersii below).
Questel (2012) observed Scolopendra alternans only once on îlet Chancel (Martinique), but he is not sure of the species identification. Given that the species is not found in either the historical Father Pinchon collection (FPM) or among numerous new samples, the presence of this native Antillean species in Martinique is under question (see Discussion below).
description: Published as part of Schileyko, Arkady, Iorio, Etienne & Coulis, Mathieu, 2024, A synthesis on the scolopendromorph centipedes (Chilopoda: Scolopendromorpha) of Martinique, with description of Cryptops (Trigonocryptops) amicitia n. sp. and new data on some Neotropical scolopendromorphs, pp. 563-599 in Zootaxa 5486 (4) on pages 565-568, DOI: 10.11646/zootaxa.5486.4.6, http://zenodo.org/record/13210600