Hatzegobatrachus grigorescui, Venczel & Csiki, 2003

Venczel, Márton & Csiki, andZOLTÁN, 2003, New frogs from the latest Cretaceous of Hateg Basin, Romania., Acta Palaeontologica Polonica 48 (4), pp. 609-616 : 610-611

publication ID	https://doi.org/ 10.5281/zenodo.13394058
persistent identifier	https://treatment.plazi.org/id/436E87E6-BB0E-FFFA-FFE2-0AD6FC4FF8B5
treatment provided by	Felipe
scientific name	Hatzegobatrachus grigorescui
status	sp. nov.

Treatment

Hatzegobatrachus grigorescui sp. nov.

Etymology: After Prof. Dan Grigorescu, University of Bucharest, whose collecting efforts in the Late Cretaceous of Haţeg Basin, Romania, resultedin discoveries of the microvertebrate localities andfrog fossils re − ported in this paper.

Holotype: FGGUB v. 433, a partial left ilium missing the distal part of iliac shaft andposterior margin of supraacetabular andsubacetabular re − gions ( Figs. 1A View Fig , 2A View Fig ).

Holotype locality, horizon, and age: Vălioara−Fântânele microvertebrate locality, about 5 km west of the village Vălioara , Haţeg Basin , Romania; middle member of the Densuş−Ciula Formation ( Grigorescu et al. 1999). The sedimentological development indicates the presence of a braided−meandering river system with large and small channels; the microvertebrate bearing sediments are grey−greenish, massive, compact, slightly variegatedmudstones of Maastrichtian age (Grigorescu and Csiki 2002).

Referred specimens: FGGUB v. 451, a partial right prearticular ( Fig. 4A View Fig ); FGGUB v. 437, a partial left prearticular ( Fig. 4B View Fig ).

Distribution.—Known only from the holotype locality.

Diagnosis.—A small−sizedanuran having an inferredsnoutvent length of about 30 mm. Differs from Ascaphus , Leiopelma , Mesophryne , Notobatrachus , Prosalirus , pelobatoids, andsome pipoids ( Rhadinosteus ), in having a well−developed dorsal protuberance of ilium. Differs from discoglossids (including Alytes , Callobatrachus , Discoglossus , Enneabatrachus , Eodiscoglossus , Latoglossus , Latonia , Paradiscoglossus , and Wealdenbatrachus ), palaeobatrachids, and most pipids in the absence of an individualised dorsal iliac crest. Resembles Bombinatorinae in having a well−developed and undivided dorsal prominence, but differs from them in having its dorsolateral margin more thickened. Differs from Bombinatorinae andGobiatinae in the absence of any waisting between the acetabular region andthe iliac shaft, resembling in this respect some leiopelmatid−grade anurans ( Notobatrachus ). Differs from rhinophrynids (including Chelomophrynus , Eorhinophrynus , and Rhinophrynus ) in having comparatively smaller pre− andsupraacetabular regions.

Description.—The holotype specimen preserves the acetabular region andproximal part of the iliac shaft ( Figs. 1A View Fig , 2A View Fig ). The supraacetabular andsubacetabular regions (some − what damaged posteriorly) are slightly expanded and are positionednearly symmetrically in relation to the centrally placed acetabular fossa. In lateral view, the acetabular fossa has the shape of an inverted, rounded, triangle, with a prominent acetabular rim dorsally and anteroventrally. Medially, the posteroventral part of the acetabular region is damaged, but there was a well−developed interiliac tubercle. In posterior view the ilioischiadic jonction is thickened. The dorsal protuberance is indistinguishable from the dorsal prominence lying entirely above the acetabular fossa. The upper margin of the dorsal prominence is thickened (especially its anterior section) andprojects slightly laterally. The preacetabular fossa is rather shallow. Ventrally to the preacetabular fossa there is a low crest for the iliacus internus muscle insertion. The iliac shaft has a rounded cross−section and lacks a dorsal crest; there is no waisting above the acetabular fossa.

Prearticular ( Fig. 4 View Fig ).—Specimen FGGUB v. 451 represents a partial right prearticular with the anterior portion of the bone andposteromedial section of spatulate extremity broken off.

The bone is slender with its anterior part bent lingually, while its posterior section is slightly curvedlabially. The coronoid process is weakly projecting with a smooth convex surface, directed dorsolingually. In its posterior section a rather shallow groove is observed. There is no obvious constriction at the level of coronoidprocess in the course of Meckel’s groove. The spatulate extremity is moderately deep and is delimitedlaterally by a sharp crest. Above the external mandib − ular crest, the lateral surface is slightly concave with a small tubercle near the ventrolabial margin. Specimen FGGUB v. 437 ( Fig. 4B View Fig ) belonged to a slightly larger individual. Its anterior andposterior part is lacking, andpreserves a convex and somewhat wider coronoid process. However, these morphological differences, compared to FGGUB v. 451, may be interpreted as intraspecific variation.

Remarks.—The ilium of Hatzegobatrachus shows a number of primitive features (little expansion of preacetabular and supraacetabular processes, lack of dorsal crest, dorsal prominence of low height, no waisting between the acetabular region andiliac shaft) in combination with few derivedones (dorsal protuberance projects laterally, well developed interiliac tubercle). The combination of the above features is often present in the extinct Gobiatinae (Roček andNessov 1993; Roček 2000), andin living Bombinatorinae. The posterior margin of the supraacetabular region in the holotype is somewhat damaged, but the outline of the dorsal margin is suggestive of a relatively small supraacetabular expansion, resembling Barbourula , Bombina , andGobiatinae. The preacetabular process is lacking in Barbourula ( Clarke 1987; Evans andManabe 1998) but is present at least in some members of Bombina ( Fig. 2B 2 View Fig ). Contrary to Hatzegobatrachus , in bombinatorine andgobiatine a little waisting is present between the acetabular region andthe iliac shaft ( Fig. 2B 2 View Fig , Roček 2000: fig. 16), while the dorsal tuberosity (also projecting laterally) is weakly developed. However, in gobiatine frogs the latter structure displays a wide range of intra− or interspecific variation (see Roček andNessov 1993: text−fig. 25A–E, pl. 9: 5, pl. 10: 4). The interiliac tubercle of the ilium is relatively small in Bombina ( Fig. 2B View Fig 1 View Fig ), versus more strongly developed in Barbourula ( Clarke 1987: figs. 6, 7) and Gobiates (Roček 2000: fig. 16). Other distinctive features of Hatzegobatrachus include the laterally oriented acetabular fossa (oriented slightly dorsolaterally in discoglossids) and the dorsally prominent acetabular rim (undeveloped in discoglossids). The undivided and laterally projecting dorsal prominence may be reminiscent of some leiopelmatid−grade anurans (e.g., Notobatrachus ) (Báez andBasso 1996). Another anuran with the ilium somewhat resembling Hatzegobatrachus is Scotiophrynepustulosa. But it lacks a dorsal protuberance of the ilium. A morphological resemblance between Scotiophryne and Zaphrissa was pointedout by Estes (1969), the latter taxon actually being a synonym of Pelobates ( Böhme et al. 1982; Sanchíz 1998). Within extinct pipids, the ilium of some members (e.g., Shelania laurenti , Xenopus romeri ) lacks a dorsal crest, but the morphology of the acetabular region andthe size and orientation of the dorsal protuberance is different (Báez andPugener 1998; Sanchíz 1998).

The prearticular assignedto Hatzegobatrachus has a small, elongatedanddorsally convex coronoidprocess. In Eodiscoglossus , Barbourula , andto a lesser degree Alytes and Bombina ( Fig. 4C View Fig ), the dorsomedial surface of the coronoid process is smooth andconvex, but much wider than in Hatzegobatrachus . In prearticular, assignedwith some doubts to Gobiatoides (Roček andNessov 1993: text−fig. 24A; pl. 14:10, andtext−fig.

24B; pl. 14: 9), the morphology of the coronoidprocess ap − proaches the condition seen in FGGUB v. 437 ( Fig. 4B View Fig ). The spatulate extremity in Hatzegobatrachus is not widened posteriorly with sharp lateral margins. In Bombina the lateral crest delimiting the pars spatulata is similarly sharp with its lateral surface concave andsomewhat crinkly; it bears a tubercle near the posterolateral margin. In Hatzegobatrachus a tubercle is present on the ventrolateral surface, but in a more anterior position.

In order to ascertain the closer relationships of Hatzegobatrachus , further skeletal material is needed from the type locality.