Pseudorhinolophus schlosseri ( Revilliod, 1917 )

Harrison, David L. & Hooker, Jeremy J., 2010, Late Middle Eocene bats from the Creechbarrow Limestone Formation, Dorset, southern England with description of a new species of Archaeonycteris (Chiroptera: Archaeonycteridae), Acta Chiropterologica 12 (1), pp. 1-18 : 8-10

Pseudorhinolophus schlosseri ( Revilliod, 1917)

* v 1917. Hipposideros schlosseri Revilliod : 15, fig. 7. Phos- phorites du Quercy, France.

v. 1986. Microchiroptera gen. et sp. indet. 3 Hooker: 245, fig. 17e–g.

Lectotype

NMB QP 875 right maxilla with C 1 –M 3, selected by Sigé (1978: 253) from the Phosphorites du Quercy.

Material

HZM 1.31792 left M 2. CL 1.79 ; CW 2.11 (Figs. 4A–B, 7A–B). HZM 3.38170 left M 1 /2. CL 1.82 ; TRI L 0.96; TRI W 1.25; TAL L 0.83 ; TAL W 1.28 (Figs. 4C–F, 7C–E). Doubtfully BMNH M36790 basal part left C 1 . CL 1.77 ; CW 1.53 (Fig. 9A–C).

Description

The left M 2 (HZM 1.31792) conforms in size with the assemblage from Ste-Néboule described by Sigé (1978: table 2) in which 40 examples of isolat- ed M 2 measured 1.6–1.87 mm in crown length and 1.94–2.21 mm in crown width. The morphology of the Creechbarrow specimen closely resembles the M 2 in a maxilla (BRE 1-775) from Le Bretou ( Sigé, 1988: 91, fig. 27). Although the postcingulum of the Creechbarrow tooth has been eroded the shape of the protocone lobe is more comformable with M 2 than M 1. Other important morphological points are the mesially curved parastyle and shorter straight metastyle; the ectoflexus is very shallow; the postprotocrista stops at the lingual base of the metacone as a result of which the protofossa is enclosed, narrow and deep as described by Sigé (1988: 90). This tooth has been compared with a cast of the lectotype ( Sigé, 1978). The M 2 from Creechbarrow has identical dimensions to the lectotype M 2 and differs only in having a less pointed mesostyle.

Pseudorhinolophus morloti ( Pictet, 1857) is smaller (M 1 CL 1.42–1.56; M 2 CL 1.32–1.55, M 1/2

CL 1.39–1.62 ( Hooker and Weidmann 2000: table 11); M 1/2 have prominent lingually projecting hypocones ( Hooker and Weidmann, 2000: fig. 37d).

Pseudorhinolophus weithoferi Revilliod, 1917 , is larger. The M 2 in a cast of the syntype (NMB QH192 ) measures CL 2.43; CW 2.56.

M36790 is the basal part of an upper left canine, described and figured by Hooker (1986: 245, fig. 17e–g). Its dimensions are very slightly larger than the series of eight C 1 from Le Bretou listed by Sigé (1988: table 4): CL 1.55–1.72; CW 1.18–1.36. It is very tentatively placed here because its morphology resembles that of Pseudorhinolophus .

HZM 3.38170 (Figs. 4C–F, 7C–E) is a well preserved left M 1 /2 with moderate wear of the cusp tips and crests, especially the paracristid, postmetacristid and metaconid, with exposure of dentine. The crown outline is subrectangular with its width greater in relation to its length than in HZM 1.31222 described below as Rhinolophidae gen. et sp. indet. The paracristid is slightly convex mesially, the metacristid almost straight. Both crests lack the pronounced angulation present in HZM 1.31222, possibly due to the more advanced wear in this specimen. The blunt paraconid projects much more lingually than in HZM 1.31222, producing the distinctly rectangular outline. The pattern of wear on the lingual aspect of the trigonid and talonid resembles that seen in the modern Hipposideros larvatus (HZM 23.35012: Kyway Chai Village, Rakhine State, Myanmar) and it is noteworthy that the small cingular ledge beneath the lingual opening of the trigonid basin seen in HZM 1.31222 is absent in this specimen as well as in the modern hipposiderid. The cristid obliqua, also worn with exposure of dentine, is attached low down on the distal trigonid wall and more distinctly lingual to the midline than in HZM 1.31222. The hypoconulid is situated buccally of the entoconid, both cusps exhibiting slight wear. The pre-entocristid is also worn, forming a narrow marginal gutter on the lingual border of the talonid, which is distinctly wider than the trigonid. The talonid is low with the hypoconid about two-thirds of the protoconid height. A well preserved narrow cingulum extends from its origin close to the paraconid around the buccal and distal crown margins to the hypoconulid. It is not robust as in Archaeonycteris and in Stehlinia and lacks the marginal crenulations present in the latter. There were two transverse roots, the distal one preserved and direct- ed slightly distally.

Good occlusion can be demonstrated with HZM 1.31792, considered to be an M 2 of this species. The

F

measurements of this specimen fall within the range of the series of 10 M 1/2 from Le Bretou listed by Sigé (1988: table 4). CL 1.62–1.82 (m = 1.70); CW 1.2–1.49 (m = 1.33, n = 10) and of 60 M 1/2 from Ste- Néboule; CL 1.76–1.95 (m = 1.84); CW 1.25–1.59 (m = 1.43) ( Sigé, 1978: table 2).

Figures

Left M1/2 in G — distal, H — lingual, I — buccal and J — occlusal views. Scale = 1 mm