Propolydesmus cretaceus, Su & Cai & Huang, 2023

Su, Yi-Tong, Cai, Chen-Yang & Huang, Di-Ying, 2023, A new species of Polydesmidae (Myriapoda, Diplopoda, Polydesmida) from the mid-Cretaceous Burmese amber, Zootaxa 5396 (1), pp. 112-123 : 113-121

publication ID	https://doi.org/ 10.11646/zootaxa.5396.1.16
publication LSID	lsid:zoobank.org:pub:A614B0EF-D584-4055-B119-978CFAD08024
DOI	https://doi.org/10.5281/zenodo.10456324
persistent identifier	https://treatment.plazi.org/id/6E2887CD-8036-FFF7-9BA4-F99296D3C0FB
treatment provided by	Plazi
scientific name	Propolydesmus cretaceus
status	sp. nov.

Treatment

Propolydesmus cretaceus sp. nov.

Material. Holotype: NIGP175097 View Materials , a well-preserved adult male ( Figs 1–3 View FIGURE 1 View FIGURE 2 View FIGURE 3 ) . Paratypes: NIGP175098 View Materials – NIGP175103 View Materials , one well-preserved adult male ( Figs 4–5 View FIGURE 4 View FIGURE 5 ), one well-preserved adult female ( Figs 6–7 View FIGURE 6 View FIGURE 7 ), one moderately preserved adult females, two moderately preserved sub-adult females. Additionally, 14 female or sex-undetermined specimens are studied.

Etymology. Name after the age of the fossils, as the species is the first formally described Polydesmidae from the Cretaceous.

Diagnosis. Differs from other Propolydesmus species by: prefemoral part of gonopod telopodite large, slightly elongate; acropodite strongly developed and falcate; exomerite relatively short, smooth, with a twisted bipartite branch.

Locality and horizon. Noije Bum near Tanai, Hukawng Valley, Kachin State of northern Myanmar; upper Albian to lower Cenomanian (mid-Cretaceous).

Description. Body length 6.0– 7.8 mm, maximum width of mid-body metazonites 0.9–1.1 mm, 20 body rings in adult (18+1+T). No distinct body size difference between male and female ( Figs 1A, B View FIGURE 1 , 4A, B View FIGURE 4 , 6A, B View FIGURE 6 ).

Head moderately to densely setose, fron wide and flatten ( Figs 1D View FIGURE 1 , 2A View FIGURE 2 , 4C, D View FIGURE 4 , 5A, B View FIGURE 5 , 6 D, E View FIGURE 6 , 7A View FIGURE 7 ). Ommatidia absent. Antennae slender and slightly clavate, moderately to densely setose, in situ reaching the posterior part of metatergite 3 if stretched dorsally; length of antennomeres 2≈3>6≈5≈4>1>7, antennomere 5, 6 wider than others ( Figs 1D View FIGURE 1 , 2A, C View FIGURE 2 , 4C, D View FIGURE 4 , 5B View FIGURE 5 , 6 D, E View FIGURE 6 , 7A View FIGURE 7 ); antennomeres 5 and 6 each with a distodorsal group of bacilliform sensilla, numbers and details of the sensilla unclear. Gnathochilarium of typical polydesmid form, detailed structures not acquirable.

Collum small, slightly convex, suboval shaped, narrower than head and following metaterga, without obvious sculpture; with 3 rows of elongate acicular seta: 5+5 along anterior margin, 3+3 on medial area, 3+3 along posterior margin; lateral corners weakly angular, each side with one laterally pointed setae ( Figs 1G View FIGURE 1 , 5F View FIGURE 5 ). Body parallelsided from ring 3 to 14. Metaterga broad, with shallow polygonal texture ( Figs 2B View FIGURE 2 , 7C, D View FIGURE 7 ); metatergal sculpture typical and moderately developed: setiferous polygonal bosses arranged in 3 transverse rows, with 3+3 on each row; metatergal seta elongate and acicular, similar to seta on collum ( Figs 2D View FIGURE 2 , 5F View FIGURE 5 , 7B View FIGURE 7 ). Paraterga well-developed, slightly wing-shaped, with 3 (metaterga without ozopore) or 4 (with ozopore) setiferous notches ( Fig. 7B View FIGURE 7 ). Ozopores located much closer to lateral than to caudal margin of paraterga, pore formula normal. Pleurites and sterna with dense small projections ( Fig. 5C View FIGURE 5 ). Legs elongate, moderately setose; tarsus long and slender, sphaerotrichomes absent or not visible; claw simple, slightly curved.

Epiproct short, conical, directed caudoventrally, with a group of 4 setiform spinnerets on tip; paraprocts suboval and slightly elongate ( Figs 2F View FIGURE 2 , 4E, F View FIGURE 4 , 5D View FIGURE 5 , 6F, G View FIGURE 6 , 7E View FIGURE 7 ); hypoproct large, subtrapeziform to sub-oval, caudal 1+1 setiferous papillae well-developed and moderately separated ( Fig. 7F View FIGURE 7 ).

Gonopods modified from leg pair 7 only ( Figs 1F View FIGURE 1 , 5E View FIGURE 5 ). Coxae of typical polydesmoid form: large, medial fused, deeply excavated ( Fig. 3A, B View FIGURE 3 ). Telopodites well exposed, suberect; prefemoral part large, moderately in length, sparsely to moderately setose ( Fig. 2E View FIGURE 2 ); femoral part short, stout, depressed along main body axis on distal part ( Figs 2E View FIGURE 2 , 3C, D View FIGURE 3 ); acropodite strongly developed, falcate in shape ( Fig. 3E, F View FIGURE 3 ); exomerite relatively short, smooth, subfalcate, set off from femorite by a sulcus and bend dorsal-caudally, with a twisted bipartite branch on basalmedial part, without other seta, spines or projections ( Figs 2E View FIGURE 2 , 3C–F View FIGURE 3 ). The groove or strip on inner side of telopodite might refer to seminal groove ( Fig. 3C, D View FIGURE 3 ), however its accurate features are not available, the opening near the base of acropodite ( Fig. 3E, F View FIGURE 3 ) might be orifice of seminal groove or accessory seminal chamber.