Nyssodesmus alboalatus Cook, 1896

Golovatch, Sergei I., Korotayeva, Alyona M. & Martínez-Torres, Daniela, 2024, Three species of the millipede family Platyrhacidae from Costa Rica: a new Barydesmus Cook, 1896 and two oldest Nyssodesmus Cook, 1896 (Diplopoda Polydesmida), Zootaxa 5538 (5), pp. 424-438 : 428

Nyssodesmus alboalatus Cook, 1896

Figs 2–5, 14

Nyssodesmus alboalatus Cook, 1896: 53 (original verbal description).

Nyssodesmus alboalatus — Moritz & Fischer, 1978: 111 (information on type material consisting of three specimens and a rectified type locality); Hoffman, 1999: 395 (provides type locality information and mistakenly refers to a male holotype); Recuero & Sánchez-Vialas, 2018: 272 (information on type material and type locality, erroneously repeating as if a male holotype was involved).

Type material. Lectotype male ( Moritz & Fischer 1978: ZMB 1391 , in alcohol), “(Rio) Puerto Viejo, plaines du Rio Sarapiquí , 150 m, Bassin du Rio San Juan, Costa-Rica, legit P. Biolley, IV 92”, designated herewith.

Paralectotypes: 1 male and 1 female, same data as lectotype ( Fig. 2A) .

Additional material examined. 1 male ( VMNH, DMT 98 , in alcohol), Costa Rica, Limón Province, Farm Hamburg, Waldbodan , 10.2846630°N, - 83.410149°W, 10 m a.s.l., 11.I.1934, F. Nevermann leg. ( Fig. 5) .

Diagnosis. Differs from congeners primarily by the usually completely dark mid-dorsal parts of metaterga with contrasting light paraterga and darker legs, distinct metatergal granulations, coupled with the rounded gonopodal tip lacking a readily discernible solenomere process ( Figs 3–5).

Brief descriptive notes. Length ca 70–93 mm (male) or 80 mm (female) ( Figs 2A, 5), width of midbody pro- and metazona up to 6 and 12 mm, respectively (male). Coloration mostly brown to dark brown, metaterga usually entirely dark mid-dorsally, with contrasting light, yellow to pallid paraterga (type series, Fig. 2A), to apparently faded and uniformly greyish ( Fig. 5). Metatergal granulations distinct ( Fig. 2). Ozopore on paratergum 10 lying ca 1–2 its diameter off lateral margin ( Fig. 3A). Gonopods ( Figs 3B, 4, 5B, C) unusually simple, acropodite ribbon-shaped and rapidly bent mesad, divided into a rudimentary solenomere (sl) and a longer, slightly sigmoid, rounded to subtruncate lateral branch (lb).

Remarks. Of the 13 formal Nyssodesmus species so far known, ten have been described from Costa Rica (Recuero & Sánchez-Viales 2018). Among them, the type species N. alboalatus has hitherto remained neither properly described nor illustrated, nor recorded beyond the type locality. Moreover, the name N. alboalatus has remained jeopardized by the older N. python ( Peters, 1865) , a species that is widespread and locally abundant in Costa Rica ( Hoffman 1999). For this reason, all available samples of N. python have also been revised.

Distribution. Presently known only from two places in Costa Rica: one the type locality in Heredia Province and the other a locality in Limón Province (see above). Originally, mistakenly stated as coming from Nicaragua ( Cook 1896), but the provenance subsequently rectified to Puerto Viejo, Costa Rica ( Moritz & Fischer 1978).