Gobiulus Dzik, 1975

Shelley, Rowland M. & Floyd, Samuel D., 2014, Expanded concept of the milliped family Spirobolidae Diplopoda: Spirobolida: Spirobolidea): Proposals of Aztecolini n. tribe and Floridobolinae / ini and Tylobolini n. stats.; (re) descriptions of Floridobolus and F. penneri, both Causey, 1957, and F. orini n. sp.; hypotheses on origins and affinities, Insecta Mundi 2014 (357), pp. 1-50 : 24

Genus Gobiulus Dzik, 1975

Gobiulus Dzik, 1975:17 .

Type- and only component species. G. sabulosus Dzik, 1975 , by original designation.

Diagnosis. Body with 40 rings including collum and epiproct. Hypostome and gula large, covering part of mentum. Ocellaria widely separated, containing around 30 ocelli. 2 nd pleurotergite extending below level of collum. Striae ventrolateral only. Paraprocts slightly re-entrant, without rims.

Distribution. Mongolia, Ömnögovi Prov., Gobi Desert.

Origin. The strata harboring these fossils derive from the late-Cretaceous Period, Mesozoic Era. They are thought to be from the Middle Campanian Stage, dating to 77 mya ( Shear et al. 2009).

Remarks. Thirteen specimens of G. sabulosus were retrieved plus one with a less deeply incised and more rounded frontoclypeal region that Dzik (1975) thought might represent a second species but did not name. The head of the holotype ( Dzik 1975, fig. 1b) clearly shows the frontal groove that is indistinct in the unnamed specimen, so we agree that Spirobolida is the correct order ( Shear et al. 2009, Shear and Edgecombe 2010). Primarily from the shape of the mentum and sterna, Dzik allied Gobiulus with Rhinocricidae and Atopetholidae but then excluded the former because of the absence of protergal scobinae. However, scobinae, if present, would normally be overhung by the caudal edges of the preceding metaterga, probably fossilize poorly if at all, and some rhinocricids lack them, so this perceived absence in a juliformian fossil is not diagnostic. Dzik also thought that the indistinct tergal divisions eliminated Gobiulus from Atopetholidae , and he excluded Spirobolidae because of the shape of the mentum and the triangular mandibular stipes. He tentatively assigned Gobiulus to the exclusively North American/ Mexican Atopetholidae , whose distribution he incorrectly reported as including Asia and North and South Africa ( Chamberlin and Hoffman 1958; Hoffman and Orcutt 1960; Loomis 1968a; Hoffman 1980a, 1998b, 1999; Bueno-Villegas et al. 2004; Shear et al. 2009; Shear and Edgecombe 2010; Shelley and Golovatch 2011). From the published illustrations of Gobiulus , we note the slightly re-entrant paraprocts that lack rims ( Dzik 1975, fig. 5a-c), which are consistent with both Atopetholidae and Tylobolini ( Table 2, row 5; Keeton 1960a, pl. 3, fig. 21; Hoffman and Orcutt 1960); spiroboline paraprocts clearly possess rims and are not re-entrant. Additionally, the widely separated ocellaria, which lie dorsal to the antennal sockets and do not extend mediad, are also consistent with Tylobolini ( Dzik 1975, fig. 1b, 6b; Keeton 1960a, pl. 1, fig. 6, pl. 2, fig. 11, 13); spiroboline ocellaria always extend mediad toward the epicranial suture and are closer together. With these anatomical similarities, we believe that Gobiulus is assignable to Spirobolidae / Floridobolinae / Tylobolini ; Dzik’s illustrations lack scale lines, but the individuals appear juvenile to us. We would never base a formal nomenclatural change of fossils solely on illustrations because rarely can associations of impression fossils with modern genera be certain, but we nevertheless think Gobiulus may be a synonym of Tylobolus , which the fossils resemble more closely than Hiltonius . Admittedly, our statements contain a degree of conjecture, but we do confirm Dzik’s perception of affinity to North American rather than Asian spirobolidans, and the fossils are consistent with our concept of Spirobolidae . For the aforementioned reasons, we do not see Spirobolinae in Dzik’s figures; Gobiulus seems to represent a rare tylobolinine that dispersed onto the Asian part of “Asiamerica” in the Cretaceous, became fossilized, and was transported to Mongolia. Gobiulus seems to support our spirobolid, “Asiamerica” hypothesis, which also applies to other North American taxa.