Otostigmus (Parotostigmus) insignis Kraepelin, 1903

Chagas-Jr, Amazonas & Souza, Emerson Marques, 2024, A review of the types of some Otostigmus (Parotostigmus) (Scolopendromorpha, Scolopendridae, Otostigminae) of the Andes mountain range, Zootaxa 5529 (3), pp. 436-460 : 442-444

Otostigmus (Parotostigmus) insignis Kraepelin, 1903

Type material examined: Syntypes ZMH, 3 males, Ecuador, Loja, 9.x.1899, E. Witt. leg.

Additional material examined: Ecuador, NMNH 31472 , 2 males and 6 females ; NMNH 31472 , 1 male , Tungurahua, 20.viii. 1937, Wm. Clarke ; NMNH 31472 , 1 male, Baños , 29.iv.1939, Wm. Clarke ; NMNH 31472 , 1 specimen, Baños , 19.x.1938, Wm. Clarke ; NMNH 31472 , 4 females, Prov. Tungurahua, Rio Blanco , 15.ix.1937, Wm. Clarke ; NMNH 03285 , 1 female, Prov. Tungurahua, Baños , 24.i.1976, P.J. Sparrylr .

Redescription of syntypes. Length: 60 mm from anterior margin of cephalic plate to posterior margin of tergite 21. Antennae with 17 articles, first two and 1/3 of dorsal face of third glabrous; Coxosternal tooth-plates with 4+4 teeth; coxosternite with an angular suture at base of tooth-plates [not described]. Tergites 4–20 with complete paramedian sutures [from 6]; tergites 9(10)–21 margined [only in tergite 21]; tergites 6–20 with (slight) median longitudinal keel [last tergites]; tergite 21 with a slight short median longitudinal keel and a shallow rounded depression in posterior border (in two types) and 1 type only with a slight short median longitudinal keel [in the anterior two-thirds with median keel, then a median longitudinal depression]. Sternites smooth, without sutures, but with depressions; a larger rounded depression in the center with two small weak rounded depressions arranged transversally at posterior border or three small rounded depression arranged as an inverted triangle [ventral plate with a large median pit deepened towards the front, often with shallow side impressions and 3 posterior pits without longitudinal furrow]; sternite 21 shorter than precedent, with a shallow median longitudinal depression; sternite 21 with posterior border slightly concave. Coxopleuron without spines, short and truncate. Legs 1–19 with one tarsal spur, 20 and 21 without [20 with or without]. Coxae 19 in males with a very short appendix [not described]; coxae 20 in males with a larger curved appendix posteriorly that overlies sternite 21. Prefemur of ultimate legs in males with a digitiform appendix, exceeding half length of prefemur; digitiform appendix slightly flattened dorsally and with a tuft of light brown hairs on the distal dorsal part.

Remarks. Otostigmus insignis was the second Otostigmus species reported from Ecuador. It was described by Kraepelin (1903) together with two other Otostigmus also from Ecuador, O. silvestrii and O. silvestrii intermedius . Verhoeff (1937) proposed the subgenus Ecuadopleurus Verhoeff, 1937 to include O. insignis and O. silvestrii . The subgenus was based solely on sexually dimorphic characters, such as a very short appendix on the coxae 19, a very large, curved appendix posteriorly on the coxae 20, and the digitiform appendix in the prefemur of the ultimate legs. However, this subgenus is not available because no type has been designated. The larger curved appendix posterior to coxae 20 is present in males of three species group name, O. insignis , O. silvestrii intermedius , and O. lavanus . The same structure on coxae 20 is also present in the males of O. silvestrii , O. mesethus , and O. parvior , but this structure is shorter than in O. insignis , O. lavanus , and O. silvestrii intermedius . Females of these taxa usually have a short appendix on the coxae of leg 20. Another sexually dimorphic feature present in the males of the five species and one subspecies of Otostigmus mentioned above is the digitiform appendage on the prefemur of leg 21. In these taxa, the digitiform appendix can vary in shape, length, and the presence and position of the tuft of hairs. The function of these dimorphic structures is still unknown in Otostigmus , and the curved appendage on the coxae of leg 20 is exclusive to Ecuadorian species.