Hipposideros Grey, 1831

Nishioka, Yuichiro, Nakagawa, Ryohei, Nunami, Shin & Hirasawa, Satoshi, 2016, Small Mammalian Remains from the Late Holocene Deposits on Ishigaki and Yonaguni Islands, Southwestern Japan, Zoological Studies 55 (5), pp. 1-21 : 8-11

Genus Hipposideros Grey, 1831

Material examined: A right maxilla with C,

P 3, P 4, M 1,M 2, and M 3 (MPM-Fo 2805); two left P 4 (MPM-Fo 2812-2813); a right P 4 (MPM-Fo 2814); two left M 1 (MPM-Fo 2815-2816); three right M 1 (MPM-Fo 2817-2819); three left M 2 (MPM-Fo 2820-2822); four right M 2 (MPM-Fo 2823-2826); a right M 1 or M 2 (MPM-Fo 2827); three left M 3 (MPM- Fo 2828-2830); a right M 3 (MPM-Fo 2831); a left mandible with P 2, P 4, M 1, and M 2 (MPM-Fo 2832); a left mandible with M 2 and M 3 (MPM-Fo 2833); two left mandibles with M 2 (MPM-Fo 2834-2835); a left mandible with M 1 and M 2 (MPM-Fo 2836); a right mandible with P 4, M 1, and M 2 (MPM-Fo 2837); a right mandible with M 1, M 2, and M 3 (MPM- Fo 3838); a right mandible with M 2 and M 3 (MPM- Fo2839); a left P 4 (MPM-Fo 2845); five left M 1 or M 2 (MPM-Fo 2846-2850); three right M 1 or M 2 (MPM-Fo 2851-2853); two left M 3 (MPM-Fo 2854- 2855); two right M 3 (MPM-Fo 2856-2857).

Locality: Sabichi Fissure and Sabichi-do Cave, Ishigaki Island.

Measurements: See Tables 2 and 3.

Description: The maxilla (MPM-Fo 2805) preserves a canine, two premolars, and three molars ( Fig. 8A). The root socket of the canine concaves dorso-ventrally. The canine is large, robust, and with a weak ridge on the buccal side and sharp keels on the anterior and posterior sides. The base of the canine is elongated antero-posteriorly, and has a distinct cingulum. The cingulum at the buccal side shows a chevron line bending almost at a right angle.

There are two upper premolars. The smaller one (usually called as P 3) is situated on the buccal side behind the canine. The larger one, or P 4, is composed of a single cusp (paracone) and has a triangular occlusal outline. The buccal surface of P 4 also shows an equilateral triangle due to the crown height almost as long as the crown length. The basal cingulum is strong. P 4 is in contact with the canine at the antero-lingual side.

Upper molars have a W-shaped pattern with a trapezoidal occlusal outline. The crown of M 1 is composed of four main cusps (paracone, metacone, protocone, and hypocone) and three styles (parastyle, mesostyle, and metastyle). The parastyle is as large as the mesostyle in the buccal view, and the metastyle is slightly weaker than the other styles. The cristas connect main cusps and styles on the buccal side, comprising a W-shaped line. The ectocingulum is smaller than the precingulum and the postcingulum. The metacone is slightly larger than the paracone. The metaconule is absent or indistinct. The hypocone is vestigially present at the postero-lingual corner. The entocingulum and the distocrista are strong, connecting with the precingulum and the postcingulum, respectively.

The occlusal pattern of M 2 is basically the same as that of M 1, although the posterior wall of M1 bends inward strongly. The crown size of M 2 is slightly smaller than that of M 1. M 3 is much reduced in the posterior part composed of the metacone and the hypocone. Thus, the occlusal surface of M 3 shows a triangular shape. The parastyle of M 3 projects more buccally than the other styles.

The mandibles (MPM-Fo 2832 and 3838) preserve cheek teeth, P 4 to M 2 and M 1 to M 3, respectively ( Figs. 8 B-C). The mandibular body is robust, with a large mental foramen below the anterior of P 2, and curves downward at the mental protuberance between the canine and P 2.

P 2 is relatively large, and has a diamond occlusal outline. The basal cingulum is prominent on both lingual and buccal sides, and shows a sharp V-letter in the buccal view. P 2 has a single root. P 3 is absent (no alveolus). P 4 develops sharply as a canine, and has a triangular occlusal outline. The basal cingulum of P 4 bends at a right angle along the cervical line. P 4 has two roots.

The lower molars have the W-shaped occlusal pattern: each trigonid and talonid basin shows an isosceles triangle outline. The trigonid is almost as wide as the talonid. The entoconid is isolated from the hypoconulid by a gap between the postcristid and the entocristid. The oblique cristid, extending from the hypoconid, runs onto the half point between the protoconid and the metaconid. The hypoflexid is very deep. The basal cingulums are strong on the anterior, posterior and buccal sides, and it is unbroken by the hypoflexid. A lingual cingulum (or entocingulid) is indistinct or absent. There are two roots on each molar.

The tooth pattern of M 2 is basically the same as that of M 1. M 2 has an interfacet at the anterior of the pricingulid for connecting with the hypoconulid of M 1. The crown size of M 2 is larger than that of M 1. M 3 reduces its posterior part, or lacks its postero-lingual region. The hypoconid of M 3 is considerably smaller than that of M 1 or M 2.

Remarks: Hipposideros turpis is a relatively large microchiropteran species with the dental formula, 1.1.2.3/2.1.2.3. This species is characterized by the upper canine overhanging anteriorly, tiny P 3, strongly reduced M 3 and M 3, no P 3, and large P 4 with two roots ( Abe 2000). Hirasawa et al. (2008) described a Hipposideros remain found from Miyako Island, with a detailed comparison with the other chiropterans. They mentioned some minor differences in lower cheek teeth between the Miyako form ( Hipposideros sp. ) and H. turpis living on Ishigaki Island: e.g., P 2 of the former expands more buccally than that of the latter. This difference supports the finding that the specimen, MPM-Fo 2832 ( Fig. 8B), from Sabichi-do Cave is similar to H. turpis living on Ishigaki Island rather than the Miyako form described by Hirasawa et al. (2008).

Distribution: Ishigaki, Iriomote, Hateruma, and Yonaguni Islands ( Sano 2009a).