CTENOCHELIDAE INCERTAE SEDIS

Tshudy, Dale M., Hyžný, Matúš, Veselská, Martina Kočová & Jagt, John W. M., 2022, Taxonomic revision of the extinct clawed lobster genus Oncopareia Bosquet, 1854 (Decapoda, Astacidea, Nephropidae), Palaeontologia Electronica (a 20) 25 (2), pp. 1-31 : 27-28

CTENOCHELIDAE INCERTAE SEDIS “ Ischnodactylus” texanus Rathbun, 1935

1935 Ischnodactylus texanus Rathbun , p.

27, pl. 3, figs. 4–6.

1941 Oncopareia texanus (Rathbun) ;

Mertin, p. 179.

2010 Oncopareia texanus (Rathbun) ;

Schweitzer et al., p. 32.

Material studied. Tshudy (1993, p. 365) examined several non-type specimens, all claw fragments, contained in collections of the Texas Memorial Museum.

Remarks. Tshudy (1993, p. 365) concluded that the studied material very likely did not belong to a nephropid, and that the palm was too rectangular to fit into Ctenocheles . The material as figured by Rathbun (1935) exhibits a morphology that is typical of the minor chelae of Ctenocheles (for details see Hyžný and Dulai, 2014) and major chelae of Gourretia and Dawsonius . Confident generic assignment is pending discovery of better material. Range and occurrence. Lower Cretaceous (Albian) at several localities in the Duck Creek Limestone, Denton Clay and Paw Paw Clay of northeast Texas ( Rathbun, 1935, pp. 27‒28).

BRACHYURA Latreille, 1802 PODOTREMATA INCERTAE SEDIS “ Oncopareia” heterodon Bosquet, 1854

1854 Oncopareia? heterodon Bosquet , p. 131, pl. 10, fig. 9a, b.

1886 Oncopareia heterodon Bosquet ; Pelseneer, p. 173.

1929 Hoploparia? heterodon (Bosquet) ; Glaessner, p. 219.

2010 Hoploparia heterodon (Bosquet) ; Schweitzer et al., p. 30.

2014 Oncopareia heterodon Bosquet ; Jagt et al., p. 100, pl. 5, figs. 1, 2.

Material studied. One of us ( JWMJ) has recognized several isolated fingers in the Bosquet Collection (IRScNB), embedded in matrix, which might be Bosquet’s originals (see Jagt et al., 2014, pl. 5, figs. 1, 2). There is a lot of additional material, from various levels within the upper Gulpen (Lanaye Member) and lower/middle Maastricht Formation (Valkenburg to Emael members) in the Liège-Limburg Basin ( Belgium, the Netherlands). The bestpreserved specimen to date is the one illustrated by Jagt et al. (2014, pl. 5, figs. 3, 4).

Remarks. Bosquet (1854) referred this form “avec doute” to Oncopareia . Known mostly by claw fingers, with only a single partial cheliped known to date; these probably belong to a brachyuran, a podotreme crab of uncertain affinities, as indicated by Jagt et al. (2014). We follow their opinion here.

Range and occurrence. Upper Gulpen (Lanaye Member) and lower/middle Maastricht Formation (Valkenburg to Emael members), all upper Maastrichtian, of southern Limburg ( the Netherlands) and adjacent Belgian provinces of Liège and Limburg .

DECAPODA INCERTAE SEDIS “ Ischnodactylus” dentatus Rathbun, 1935

Figure 14G

1935 Ischnodactylus (?) dentatus Rathbun , p. 65, pl. 14, figs. 19–22.

1941 Oncopareia dentatus (Rathbun) ; Mertin, p. 179.

2010 Oncopareia dentatus (Rathbun) ; Schweitzer et al., p. 31.

2010 Ctenocheles dentatus (Rathbun) ; Schweitzer et al., p. 40.

2014 Ctenocheles dentatus (Rathbun) ; Hyžný and Dulai, table 2.

2015 Ctenocheles dentatus (Rathbun) ; Hyžný and Klompmaker, supplement 1.

Material examined. A single isolated finger,

USNM MO495109 (holotype).

Remarks. According to Rathbun (1935, p. 65),

each of the fingers studied by her was equipped with “low, triangular, thick” (i.e., not acicular) dentition, unlike that of Oncopareia or Ctenocheles . Although Hyžný and Dulai (2014) and Hyžný and Klompmaker (2015) treated Ischnodactylus dentatus as a representative of Ctenocheles , they did not discuss the species in detail. In the present taxonomic re-evaluation, we propose to remove this taxon from Ctenocheles , based on the lack of acicular dentition, typical of the genus. Unfortunately, the isolated fingers are difficult to assign to any particular group of decapod crustacean. Similar fingers can be present equally in some brachyuran crabs or axiidean ghost shrimp.

Range and occurrence. Middle Eocene of Mississippi, USA ( Rathbun, 1935).

Figures

FIGURE 14. Non-astacidean decapod species with pectinate claws. A–B, Ctenocheles cookei (Rathbun, 1935), left propodus in inner (A) and outer (B) lateral views (holotype, USNM 371511). C–D, Ctenocheles cultellus (Rathbun, 1935), incomplete dactylus (A) and fixed finger (B) in upper, lower and lateral views (from Rathbun, 1935, pl. 14, figs. 7–12). E, Ctenocheles inaequidens (Pelseneer, 1886), right major claw (holotype, from Pelseneer, 1886, text-fig. 1). F,?Ctenocheles pectiniformis (Böhm, 1891), isolated claw (from Böhm, 1891, pl. 1, fig. 2, 2a). G, “Ischnodactylus” dentatus Rathbun, 1935, isolated finger (USNM MO 495109).