Otostigmus (Parotostigmus) Pocock, 1896

Schileyko, Arkady A., Vahtera, Varpu & Edgecombe, Gregory D., 2020, An overview of the extant genera and subgenera of the order Scolopendromorpha (Chilopoda): a new identification key and updated diagnoses, Zootaxa 4825 (1), pp. 1-64 : 44

(!) Otostigmus (Parotostigmus) Pocock, 1896

Figs 97–100

Synonyms. Androtostigmus Verhoeff, 1937, Ecuadopleurus Verhoeff, 1937, Congobius Dobroruka, 1968 .

Type species. Branchiostoma scabricauda Humbert & Saussure, 1870 (by subsequent designation of Attems 1928).

Diagnosis. Median tooth of labrum well developed. Second article of telopodite of maxilla 2 with or without dorsal distal spur; pretarsus with ( Fig. 100 ) or without accessory spines (see Remarks below). Forcipular tooth-plates present ( Fig. 100 ), trochantero-prefemur with well-developed process (as in nominate subgenus; figs 55, 58 in Schileyko 2014). Tergites with longitudinal keels in some species (figs 49–51 in Schileyko 2014). Sternites without (in some species with poorly-developed incomplete) paramedian sutures, in most species with median and lateral depressions (fig. 55 in Schileyko 2014) developed to varying degrees. LBS 7 lacking spiracles, the latter with a deep atrium. In the overwhelming majority of species legs with tarsal spur(s). Posterior margin of ultimate tergite ( Fig. 98 ) of the male without elongated projection. Coxopleural process very short and rounded apically, oriented caudad (with or without apical spines) or virtually lacking ( Figs 97, 99 ), if so a few apical spines may be situated at its place. Prefemur of the ultimate leg ( Figs 97–99 ) without both spines and corner spine. In a dozen of the known Parotostigmus species the interior surface of the male’s prefemur bears a digitiform process ( Figs 97–99 )—a cylindrical (in some species clavate) projection attached to the base of the prefemur (see also Schileyko 2014: 177). Ultimate pretarsus well-developed.

Number of species. “More than 50 species” sensu Edgecombe & Bonato (2011: 400), 53 ( Bonato et al. 2016).

Sexual dimorphism. Present in ca 20 species.

Remarks. Treated as a subgenus in Edgecombe & Bonato (2011: 402), Chagas-Jr (2012: 1, 2016: 36), Vahtera (2012a: 13, 2013: 594), Schileyko (2014: 177).

The presence of both spurs on the telopodite and/or accessory spine(s) of maxillae 2 ( Fig. 100 ) may be subject to individual and/or intraspecific variability in Parotostigmus. For example an adult male of O. (P.) diringshofeni Bücherl, 1969 (Rc 7870 in ZMMU from Peru) has the right pretarsus with one accessory spine (the left one has none) and the left telopodite with usual dorso-distal spur on the second article (the right telopodite has no such spur). At the same time, an adult female of O. (P.) pococki Kraepelin, 1903 (Rc 7563 in ZMMU from Peru) has maxillae 2 with both a pretarsal accessory spine and a telopodite spur. An adult male of O. (P.) scabricauda (Humbert & Saussure, 1870) (Rc 6346 in ZMMU from Peru) has both these appendages with a well-developed telopodite spur but only one pretarsus is equipped with a recognizable accessory spine. We should note that accessory spine(s) are quite slim in many species, delicate and closely attached to the pretarsus, sometimes being so hardly visible that an inexperienced person may easily overlook them (see also Lewis 2004). Summing up, we do not consider these structures reliable for the taxonomy of Parotostigmus.

The presence of both tergal keels and tergal spinules may vary intraspecifically in this subgenus; Schileyko (2014: 177) wrote: “For example, in O. (P.) scabricauda (Humbert & Saussure, 1870) , the spinules may be arranged along the keel (“spinulated keels”) but it is sometimes difficult to decide whether a specimen has tergal keels or just rows of spinules”.

Figures

FIGURES 97–101. Otostigmus (Parotostigmus) scabricauda (Humbert et Saussure, 1870); Ad. male Rc 6730 97 LBS 21 and prefemora + femora of ultimate legs ventrally; Otostigmus (P.) salticus Schileyko, Iorio & Coulis, 2018; Ad. holotype male MNHN 460 98 posterior margin of ultimate tergite + prefemora of ultimate legs dorsally; Otostigmus (P.) diringshofeni Bücherl, 1969; Ad. male Rc 7981 99 LBS 21 + prefemora of ultimate legs ventrally; Otostigmus (P.) salticus Schileyko, Iorio & Coulis, 2018; Ad. holotype male MNHN 460 100 anterior margin of forcipular coxosternite + maxillae 2 ventrally; Ethmostigmus rubripes spinosus (Newport, 1845); Juv. Rc 7174 101 left side of ultimate LBS + ultimate legs laterally; (as)—accessory spine, (bs)—basal suture of forcipular tooth-plate, (cp)— practically reduced spineless coxopleural process, (csp)—corner spine of ultimate prefemur, (cx)—coxopleuron, (dg)—digitiform process of ultimate prefemur, (p2)—pretarsus of maxilla 2, (pf)—ultimate prefemur, (pr)—trochantero-prefemoral process, (pst)—penultimate sternite, (pts)—ultimate pretarsus, (su)—ventral spines of ultimate prefemur, (tp)—forcipular tooth-plate, (ut)—ultimate tergite.