Stenotaenia sorrentina, (ATTEMS, 1903)

Bonato, Lucio & Minelli, Alessandro, 2008, Stenotaenia Koch, 1847: a hitherto unrecognized lineage of western Palaearctic centipedes with unusual diversity in body size and segment number (Chilopoda: Geophilidae), Zoological Journal of the Linnean Society 153 (2), pp. 253-286 : 273-276

STENOTAENIA SORRENTINA ( ATTEMS, 1903)

Geophilus sorrentinus Attems, 1903: 228 (original description); 1929a: 161 (in key), 175 (redescription); 1947: 111 (in key). Verhoeff, 1943b: 78 (redescription). Lewis, 1994: 39 (redescription; as synonym of G. linearis ), figs 1–9.

Geophilus forficularius Fanzago, 1881b: 378 (original description); 1881a: 13 (redescription). Syn. nov.

Geophilus linearis abbreviatus Verhoeff, 1925: 74 (original description); 1943a: 70 (redescription). Clinopodes linearis abbreviatus: Attems, 1929a: 203 (in key), 205 (redescription); 1947: 120 (in key). Clinopodes abbreviatus: Matic, 1972: 65 (in key), 95 (redescription). Syn. nov.

Type locality: ‘Mte. Faito’ = Monte Faito , in the Sorrento Peninsula ( Italy) .

Type material: Holotype, female, 22-mm long; held in the Naturhistorisches Museum, Vienna, NHMW6101 ( V. Stagl, pers. comm.).

Diagnosis: A Stenotaenia species of intermediate body size (total length reaching at least 3.5 cm); c. 53–67 leg-bearing segments; labrum either with or without a single tubercle; first maxillae with distinct lappets on the coxosternum, and with small lappets on the telopodites; chitin lines of the forcipular coxosternum reaching the anterior condyles; anterior margin of the forcipular coxosternum angulated; forcipular intermediate articles distinct; sternal pore areas in the anterior part of the trunk oval, longer than wide, and placed on the posterior half of each sternum; each coxopleuron with one anterior and one posterior pouch with pores (see also Table 3).

Taxonomic history: The original description of this species was quite incomplete, so its true identity remained uncertain and no other specimens were referred to it. The holotype was redescribed and illustrated in detail by Lewis (1994), who, however, regarded it as a juvenile of G. linearis .

Assignment to Stenotaenia: It is assigned confidently to Stenotaenia (comb. nov.), based on the redescription of the holotype by Lewis (1994) (Table 2), as well as on our own examination of other representative specimens from most of the known range of the species ( Fig. 6 ). Stenotaenia sorrentina shares all major diagnostic characters of the genus, including the shape of the labrum, the features of the maxillary complex and the mandibles, the general structure of the forcipular segment, the pattern of the sternal pore areas and of the coxal pores, and features of the legs of the last pair.

Validity: It is considered here a distinct species, as it can be distinguished from other species occurring in the same region, at least in body size and in the range of variation of trunk segment number ( Table 3). Actually, many authors identified representative specimens of S. sorrentina as S. linearis , based on a larger concept of this latter species, and Lewis (1994) indeed synonymized it explicitly under S. linearis (Lewis, 1994) . However, our comparative observation of representative material revealed differences in body size and in the range of variation of segment number, correlated with geographical distribution, even though further investigations are required to assess the specific identity of most populations from the Liguria region, which are morphologically somehow intermediate in the putative diagnostic traits. Furthermore, the distinction between S. sorrentina and other nominal species in the Balkan Peninsula, namely S. antecribellata and S. cribelliger , have to be considered provisional, pending critical evaluation of the putative diagnostic traits.

Remarks on synonyms

Geophilus forficularius Fanzago, 1881 . Geophilus forficularius was described by Fanzago (1881b) from a series of specimens of both sexes from near Sassari, in Sardinia ( Fanzago, 1881a), but it was largely ignored by subsequent authors (e.g. Attems, 1929a). Berlese (1903) listed it as a synonym of Henia vesuviana ( Newport, 1845) , without any comment, whereas Minelli (1983b) suggested it could be a synonym of Geophilus carpophagus . The original description does not contain many of the most useful diagnostic characters, but the combination of the given characters (mainly, quite short antennae and legs of the last pair, presence of a claw on the last legs, and sexual difference in the width of the last telopodites) suggests that G. forficularius most probably represents a Stenotaenia species. It is worth noting that Fanzago (1881b) explicitly recognized that G. forficularius resembled S. linearis , stressing that the two species were different in the shape of the antennae and the relative elongation of the legs of the last pair, but these putative differences are not obvious from the descriptions provided by the author ( Fanzago, 1881a, b). Conversely, the characters described do not agree with any other geophilomorph species known to occur in Sardinia. In particular, the legs of the last pair in male H. vesuviana are not provided with an evident claw, and are so swollen that they cannot be curved, evidently, as described in male G. forficularius . The antennae of G. carpophagus are significantly more elongated than those observed in specimens of G. forficularius representative of both sexes and different in size. A revision of published faunistic records ( Minelli, 1983b) and our direct examination of specimens from Sardinia together suggest that S. romana and S. sorrentina are the only known species of Stenotaenia occurring on the island. We are confident in recognizing G. forficularius as a synonym of S. sorrentina , as S. sorrentina is the only species compatible with the few characters described for G. forficularius , including the limited elongation of the antennae, the lack of tubercles on the forcipules, the dimorphic shape of the last pair of legs, and the presence of an evident claw in the last legs of both sexes. It is worth noting that S. sorrentina is also known to occur in the area from which G. forficularius was described. Even though G. forficularius is the senior name, we do not think that it would be advisable to resurrect this almost neglected name as the valid name for this taxon, especially because of the residual uncertainty arising from both the lack of the original material and the poor quality of the original description. As the conditions for the reversal of precedence (ICZN: art. 23.9) are not met, the matter has been referred to the International Commission on Zoological Nomenclature for a ruling under the plenary power ( Bonato & Minelli, 2007).

Geophilus linearis abbreviatus Verhoeff, 1925 . Geophilus linearis abbreviatus was described by Verhoeff (1925) from two specimens, one from the locality ‘Corpo di Cava’ in the Sorrento Peninsula, and the other from Ferrania in Liguria. Some authors did not accept this taxon as distinct from G. linearis (e.g. Lewis, 1994), but most of them accepted it as either a subspecies or a distinct species, and even identified other representative specimens mainly from the Italian Peninsula, the Dinarids, and the Carpathians (e.g. Verhoeff, 1937b, 1943a; Matic, 1972; Minelli & Zapparoli, 1985, 1992; Kos, 1995, 1996; Kos & Praprotnik, 2000). Through direct examination of the holotype of G. sorrentinus, Lewis (1994) demonstrated the morphological identity between G. sorrentinus and G. linearis abbreviatus , but he considered both names as junior synonyms of G. linearis . As G. sorrentinus is recognized here as the distinct species S. sorrentina , G. linearis abbreviatus has to be synonymized under S. sorrentina . Apart from the morphological consistency among the type specimens, it is worth noting the geographical closeness between one of the localities of the syntypes of G. linearis abbreviatus and the type locality of G. sorrentinus in the Sorrento Peninsula.

Distribution: Populations reliably referred to S. sorrentina occur through most of the Italian Peninsula, from the Maritime and Ligurian Alps to Gargano and Calabria, and also from Elba and some minor islands such as Ponza, Palmarola, Zannone, Ventotene, Capri, and Ischia ( Verhoeff, 1931, 1940, 1942, 1943a; Matic & Darabantu, 1969), as well as Sardinia. Records of specimens with 59–63 leg-bearing segments from the eastern part of Sicily ( Silvestri, 1897; under G. linearis ) should most probably be referred to S. sorrentina . Conversely, published records for G. abbreviatus from other regions, mainly in the Balkan Peninsula ( Verhoeff, 1937b; Matic, 1972; Kos, 1995; Kos & Praprotnik, 2000), need to be reassessed, given the uncertain taxonomic relations between S. sorrentina and other nominal Stenotaenia species from the same general area, namely S. antecribellata and S. cribelliger . Specimens from Corsica with 63–69 legbearing segments ( Léger & Duboscq, 1903; new locality, see Appendix) may belong to S. sorrentina , but further investigation is needed.

Figures

Figure 6. Microscopic images of a female specimen of Stenotaenia sorrentina (Attems, 1903) from Palmarola Island (Italy: Tyrrhenian Sea) (23-mm long, with 61 leg-bearing segments; 3-IV-1966 Consiglio lg, collection A. Minelli): (a) head, ventral; (b) clypeus and maxillary complex, ventral; (c) sternum of leg-bearing segment X; (d) forcipular segment, ventral.