Eocenochelus lacombianus, Pérez-García, Lapparent de Broin & Murelaga, 2017
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publication ID |
https://doi.org/ 10.26879/687 |
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publication LSID |
lsid:zoobank.org:pub:1D985176-5AD4-45FF-8BD7-C4AD17C7DE52 |
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persistent identifier |
https://treatment.plazi.org/id/03814F39-FFA8-4A3D-FEFD-E4E3F57384B5 |
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treatment provided by |
Felipe |
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scientific name |
Eocenochelus lacombianus |
| status |
sp. nov. |
Eocenochelus lacombianus sp. nov.
Figures 6.50-6.57 View FIGURE 6 , 7 View FIGURE 7
zoobank.org/ AB1F3F7C-E722-479D-AE9D-195192927714
Holotype. MNHN.F EBA 534 ( Figure 7 View FIGURE 7 ), a partial shell preserving the relatively complete dorsal carapace ( MNHN.F EBA 534.1), the nearly complete plastron ( MNHN.F EBA 534.2); and fragmentary remains of both hemipelves ( MNHN.F EBA 534.3 and MNHN.F EBA 534.4) ( Figure 6.50-6.57 View FIGURE 6 ).
Etymology. The specific name is in honor of Laurent Lacombe (Ouveilhan, France), who discovered the holotype and donated it to F. de Lapparent de Broin, who deposited it in the MNHN.
Type locality and horizon. Soulane (from the name of an occasional brook), Jonquières, Aude, Languedoc-Roussillon-Midi-Pyrénées, France ( Figure 2 View FIGURE 2 ) ( Vigneaux, 1975). Grey-blueish marls with abundant remains of the gastropods Batillaria spp. , upper part of the Upper sandstone-marly ormation, early Ypresian (from the upper part of the Ilerdian, at contact with the Ypresian continental molasse, toward the middle part of the lower Cuisian), early Eocene ( Plaziat, 1984a, 1984b; Ellenberger et al., 1987).
Diagnosis. Member of Eocenochelus with seven neurals, lacking medial contact of the sixth pair of costals (differing from Eocenochelus farresi but sharing with Eocenochelus eremberti the presence of at least seven neurals); wide pubic scar, its width being approximately half of its length (not shared with Eo. eremberti and not known in Eo. farresi ); presence of a well-developed posterior branch of the ischiatic scar reaching the short dorsal anal scute on the anal notch border, the distance from its posterior tip to the anal notch being about one third of the maximum length of this branch (not shared with Eo. eremberti and Eo. farresi , and not reaching the xiphiplastral point as in Eo. farresi ); relatively long epiplastral symphysis, its length being about half of that of the entoplastron (shared with Eo. eremberti but not with Eo. farresi ); intergular triangular, with well-developed posteriorly convergent lateral margins, and the anterior border being almost as wide as that of each gular (shared with Eo. farresi but not with Eo. eremberti ); relatively short overlap of the latero-posterior region of the humeral scutes on the hyoplastra (shared with Eo. eremberti but not with Eo. farresi ); notably narrow posterior plastral lobe (shared with Eo. farresi but not with Eo. eremberti ) but with a slightly concave border (unique to this species); relatively wide and short anal notch with straight borders, its length being about half of its width (not shared with Eo. farresi ).
Description. MNHN.F EBA 534 has a relatively small shell size. The carapace is relatively wide for its length (maximum length interpreted as close to 29.5 cm, and maximum width of about 25 cm, these dimensions being affected by a postmortem moderate flattening). The maximum length of its plastron is 29.3 cm ( Figure 7 View FIGURE 7 ). It lacks a medial keel on the carapace ( Figure 7.1-7.5 View FIGURE 7 ). There are seven neurals. The second to sixth neurals are hexagonal, almost as wide as long, their latero-anterior margins being shorter than the latero-posterior ones. The seventh neural is pentagonal and as wide as long. Both the seventh and eighth costals are in contact medially. Posterior peripheral points are not present. The axillary processes have a relatively long contact with the first pair of costals, anteriorly reaching the posterior margin of the second pair of peripherals. The inguinal processes slightly contact in a forward direction the lateral region of the fifth costals in a rounded area, and rearwardly they reach to the antero-medial area of the eighth peripherals. The iliac scars are located on the visceral region of both the seventh and the eighth costals. The first vertebral scute is wider than the nuchal plate. The second to fourth vertebrals are hexagonal; the posterior margin of the fourth is significantly shorter than the anterior one and the latero-anterior margins are shorter than the latero-posterior margins. The width of the second to fourth vertebrals is similar. The fifth vertebral is probably heptagonal, being posteriorly wide. The first pair of marginals overlaps less than half of the nuchal. Viscerally, the marginal scutes are very short, except for the posterior ones, which are relatively long and overlap a markedly and thick bordering lip.
The length of the plastron of MNHN.F EBA 534 is close to 30 cm and its bones are thin. The posterior plastral lobe is narrower than the anterior ( Figure 7.6-7.9 View FIGURE 7 ). The anterior is subrounded, its length being greater than half of its width. It lacks well-developed gular protrusions, but the intergular anterior border is rounded. The epiplastral symphysis is long, its length being about half of that of the rhomboidal entoplastron. The hyoplastra are longer than the hypoplastra. The lateral margins of the posterior plastral lobe are strongly convergent posteriorly and slightly concave. Because of the basal narrowness, the inguinal notches are relatively wide and a relatively shallow anal notch is present. Its length is about half of its width. The lateral margins are nearly straight. The gulars are in contact along the midline, posteriorly to the shorter intergular scute. Anteriorly, they are barely wider than the intergular. The intergular overlaps the most anterior region of the entoplastron. The lateral margins of this scute are strongly convergent posteriorly. Only the most lateral region of each humeral scute barely overlaps the anteriormost tips of the hyoplastra. The gular scutes are medially shorter than the humerals. The pectoral scutes do not contact the mesoplastra. The distance of the abdominal scutes to the entoplastron is almost equal to the length of this plate. The anterior half of the femoral scutes overlaps the hypoplastra, and this overlap is longer than that of the abdominals. The anterior margin of the anal scutes is located far behind the hypoplastra. Thus, on the xiphiplastra, the anal lateral borders are slightly longer than those of the femorals, the lateral margins of the anals being 24% longer than those of the femorals. The dorsal expansion of the plastral scute borders is poorlydeveloped. The pubic scars are relatively wide, their width being approximately half of their length. A well-developed posterior branch of each ischiatic scar is present, its posterior tip being close to the anal notch border inside the xiphiplastral point.
The fragmentary ilia are preserved, with the pubic acetabular part of the left side, and the pubic and ischiatic acetabular parts of the right side ( Figure 6.50-6.57 View FIGURE 6 ). The acetabular pubic part is elongated relative to the whole acetabulum width. The iliac shaft is slightly narrrower for its height than in Er. madagascariensis and in Eo. eremberti .
| MNHN |
Museum National d'Histoire Naturelle |
No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.