Discoglossus Otth, 1837
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publication ID |
https://doi.org/ 10.5252/g2014n4a4 |
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DOI |
https://doi.org/10.5281/zenodo.4837336 |
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persistent identifier |
https://treatment.plazi.org/id/03D6987B-4475-B128-FF54-119AFBF9E3AC |
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treatment provided by |
Felipe |
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scientific name |
Discoglossus Otth, 1837 |
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Genus Discoglossus Otth, 1837 View in CoL or Latonia Meyer, 1843
( Fig. 1 View FIG A-C)
TYPE SPECIES. — Discoglossus pictus Otth, 1837 (by monotypy) or Latonia seyfriedi von Meyer, 1843 (by monotypy).
MATERIAL EXAMINED. — Four incomplete maxillae ( SPV 714), one angular ( SPV 715), two urostyles ( SPV 716), one scapula ( SPV 702), one humerus ( SPV 703), nine ilia ( SPV 701 and SVP 717).
DESCRIPTION
Ŋe ilium bears a dorsal crest and its pars ascendens ends as an elongate ischiatic process. Ŋe posterior border of the crest is thickened; the thickened part forms the tuber superius. Ŋe angle formed by the pars ascendens and the tuber superius is widely obtuse. Ŋe urostyle is provided with two cotyles and a pair of transverse processes. Ŋe scapula is short dorsoventrally, more specifically the pars suprascapularis is not elongate dorsoventrally. Ŋe incomplete humerus had likely a paraventral crest; the humeral condyle is shifted laterally, whereas the diaphysis was likely comparatively straight. Ŋe maxillae are not ornamented and their infraorbital areas are relatively deep. Ŋe coronoid process of the angular is short and it is tilted medially; the medial border of the process forms some dorsal tubercles and pits. Ŋe bone lacks a paracoronoid process.
DISCUSSION
Assignment to the Alytidae (formerly Discoglossidae ) is supported by the combination of the following features: ischiatic process of the ilium elongated posteriorly, presence of two transverse processes on the urostyle, scapula short dorsoventrally, presence of a paraventral crest on the humerus, infraorbital area of maxillae comparatively deep, and coronoid process of the angular inclined medially.
Within alytids, the presence of a dorsal crest on the ilium and the tuber superius formed by a thickening of the posterior border of this crest are characteristic of the “ Discoglossus group”. Ŋis referral is consistent with the presence of two cotyles on the urostyle and the absence of a clear curvature of the humeral diaphysis.
Ŋe “ Discoglossus group” includes two extant genera ( Discoglossus and Latonia ) that are known also in the European Cenozoic. It is generally difficult to discriminate between these two genera, as shown by the fact that the living Latonia nigriventer (Mendelssohn & Steinitz, 1943) was long assigned to Discoglossus ( Biton et al. 2013) . Among fossils, the size was often used as one of the main “diagnostic” features. Extinct Latonia are larger than Discoglossus , but the recent referral of D. nigriventer to Latonia has shown that the size cannot be significant. Reliable osteological features were listed by Biton et al. (2013); unfortunately, none of these characters is preserved on the specimens from Saint-Privat-des-Vieux. In addition, a peculiar character occurs on the angular of the fossil: the medial part of the coronoid process forms a border bearing some pits and tubercles that face dorsally. Such a feature is observed for the first time. Consequently, the fossil from Saint- Privat-des-Vieux cannot be confidently referred to either Discoglossus or Latonia . Whatever the genus, this frog likely required the permanent presence of fresh water.
Ŋe earliest probable Latonia was reported from the earliest Oligocene (MP 21; Rage & Roček 2003), the referral at genus level of older alytids being questionable. Latonia was frequently reported from the late Cenozoic of Europe ( Roček 1994; Roček & Rage 2000). Ŋe earliest confirmed Discoglossus is known from the latest Oligocene (MP 30), although a form close to the genus was recovered from MP 21 ( Rage & Roček 2003). Ŋese two genera have never been reported together from the same locality.
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