Lyrischapa sismondai (d’Archiac & Haime, 1853), d'Archiac & Haime, 1853

Merle, Didier, Pacaud, Jean-Michel, Métais, Grégoire, Bartolini, Annachiara, Lashari, Rafiq A., Brohi, Imdad A., Solangi, Sarfraz H., Marivaux, Laurent & Welcomme, Jean-Loup, 2014, Volutidae (Mollusca: Gastropoda) of the Lakhra Formation (Earliest Eocene, Sindh, Pakistan): systematics, biostratigraphy and paleobiogeography, Zootaxa 3826 (1), pp. 101-138 : 112

Lyrischapa sismondai (d’Archiac & Haime, 1853)

( Fig. 4 M–N)

Voluta sismondai d’Archiac & Haime, 1853: 326 , p1. 31, figs. 25.

Voluta sismondai d’Archiac, 1850: 298 (nomen nudum).

Aulicina pusiola Cossmann & Pissarro, 1909: 26 , pl. 2, fig. 34, pl. 3, figs. 4, 5. Volutoconus corrugatus Cossmann & Pissarro, 1909: 28 , pl. 3, figs. 6, 7.

Aulica sismondai . Vredenburg 1923: 267 [new combination].

Aulica (Aulicina) sismondai . Cotter in Vredenburg 1928: 38.

Eovasum sismondai . Cox 1930: 186 in part (pl. 21, figs 1–4), see Givens (1991) [new combination]. Eovasum haimei (misidentification as Voluta haimei d’Archiac & Haime, 1853 ). Iqbal 1972: 64, pl. 17, fig. 8. Lyrischapa sismondai . Givens 1991: 666, figs 3.9–3.11, 4.1, 4.2, 4.5 (non figs 4.3, 4.6) [new combination].

Material. 1 spm (stn 3: CPAG.RAN. I.9, cast MNHN.F. A50347 ); 1 spm (stn 6: CPAG.RAN. I.10, cast MNHN.F.A50348).

Comments. In order to avoid confusion with Lyrischapa haimei, Givens (1991) gave a supplementary description for L. sismondai . According to this author, L. sismondai exhibits a larger protoconch, a deeper shoulder sinus and its spiral sculpture differs by having threads of uniform size and spacing on the spire, rather than two sizes of threads alternating. The two specimens collected at Jhirak in the Lakhra Formation and at Jamshoro in the Bara Formation are no more than 30–40 mm in height and have a high spire. They are rather similar to specimens from the Hangu Formation (NHMUK PI G49443, G49444, G49445) and from the Lakhra Formation (NHMUK PI G50319) illustrated in the paper by Givens (1991), but they differ from the largest specimen (NHMUK PI G92737) from the Ypresian (cf. Wardlaw et al. 2007) of the Nammal Formation, Salt Range, Pakistan) illustrated by this author ( Givens 1991, figs 4.3, 4.6). Numerous specimens collected in the Lakhra Dome provide a good ontogenetic series linking juveniles with the largest specimens, such as those figured by Givens (1991) and Cossmann & Pissarro (1909, pl. 2, fig. 30, pl. 8, fig. 2). Although they share a large protoconch, these juveniles display many differences from L. sismondai . At the same size (H 40 mm), they exhibit a lower spire and a wider shape, their spiral sculpture is obsolete on the spire and missing on the last whorl, except on the base which bears some fine threads, and their shoulder spines are acute and better developed. Specimens of a larger size and very large specimens of around H 80 mm have the same characters on their early teleoconch whorls, showing that they belong to the same species, which is described here below as Lyrischapa vredenburgi sp. nov. However, they also demonstrate that the specimens attributed to L. sismondai do not correspond to the early stages of growth of the largest specimens often attributed to this species. Thus, the supplementary description by Givens (1991) is still a composite description and the character “9–12 prominent spines on the shoulder” should be replaced by: “9–10 short, rounded spines on the shoulder”. By its biconical shape, by the configuration of the shoulder sinus and by its short, rounded shoulder spines, L sismondai appears closely related to Diconomorpha elegans ( Douvillé, 1929) [type species of Diconomorpha Wenz, 1943 = Diploconus Douvillé, 1929 , non Candèze (1860) by original designation] from the Danian of Sindh (Kadhro Formation). Although these Danian specimens do not display the superficial sculpture observed in L. sismondai , because they are poorly preserved, they are so similar that, according to Givens (1991), generic distinction seems unjustified.

Stratigraphic range. Hangu Formation: Hangu Shales ( Cox 1930); Upper Bara Formation: Jamshoro (this paper); Lakhra Formation: Jhirak ( Cossmann & Pissarro 1909; this paper).

Figures

FIGURE 4. A. Lyria sp., CPAG. RAN. I. 1, stn 5; B – H. Mitreola brohii sp. nov., B – C (holotype, CPAG. RAN. I. 2, ventral (B) and dorsal (C) views, stn 4), D (paratype 1, CPAG RAN. I. 3, ventral view, stn 4), E – F (paratype 2, CPAG. RAN. I. 4, ventral (E) and dorsal (F) views, stn 4), G – H (paratype 3, CPAG. RAN. I. 5, juvenile, ventral view (G) and enlarged view of the spire (H), stn 4); I – K. Lyriopsis cossmanni (Vredenburg, 1923), I – J (CPAG. RAN. I. 6, ventral view (I) and enlarged view of the spire (J), stn 4), K (CPAG. RAN. I. 7, ventral view, stn 4); L. Lyrischapa haimei (d’Archiac & Haime, 1853), CPAG. RAN. I. 8, ventral view, stn 6; M – N. Lyrischapa sismondai (d’Archiac & Haime, 1853), M (CPAG. RAN. I. 10, ventral view, stn 6), N (CPAG. RAN. I. 9, dorsal view, stn 3). Scale bars: B – G, I, K – N = 10 mm; A, H, J = 5 mm.