New Miocene Icarops material (Microchiroptera: Mystacinidae) from Australia, with a revised diagnosis of the genus SUZANNE HAND, MICHAEL ARCHER & HENK GODTHELP HAND, S.l., ARCHER, M. & GODTHELP, H., 2001:12:20. New Miocene lcarops material (Microchiroptera: Mystacinidae) from Australia, with a revised diagnosis of the genus. Memoirs of the Association of Australasian Palaeontologists 25,139-146. ISSN 0810-8889 New fossil material referable to Icarops paradox Hand et al., 1998 is described from the early Miocene Judith's Horizontalis Site in the Riversleigh World Heritage Property of northwestern Queensland. Fused dentaries contain the partial lower dentition of I. paradox. The diagnosis of the genus Icarops is revised. The new material confirms the identity of Icarops species as mystacinids and enablesre-examination of interrelationships between extinct and extant members of this Gondwanan bat family. S.J: Hand, M. Archer* & H. Godthelp, School of Biological Science, University of New South Wales,New South Wales, 2052; * also Australian Museum, 6-8 College St, Sydney, New South Wales,2000. Received ]4 December 2000 Keywords: Mystacinidae, Icarops, Mystacina, bat, lower dentition, Miocene, Riversleigh THE FIRST pre-Pleistocene record for the QMF refers to specimens held in the fossil Mystacinidae and first record of this bat family collections of the QueenslandMuseum, Brisbane. from outside New Zealand were reported by Hand et al. ( 1998) from Miocene sedimentsin Australia. SYSTEMAllC PALAEONTOLOGY Three species of the new mystacinid genus Icarops were described: Icarops breviceps from OrderCIllROPTERAB1wnenbach, 1779 the middle Miocene Bullock Creek deposit of the SuborderMICROCIllROPTERA Dobson, 1875 Northern Territory; I. aenae from the early SuperfamilyNocmIoNoIDEA Van Va1en, Miocene Wayne's Wok deposit, D Site Plateau, 1979 Riversleigh, northwestern Queensland; and I. Family MYSTACINIDAE (Gray, 1843) paradox from the early Miocene Neville's Garden Site, D Site Plateau, Riversleigh. The Australian Icarops Hand et al., 1998 mystacinids were described mainly on the basis of dentaries; only I. breviceps was represented Type species. Icarops breviceps Hand, Murray, also by teeth: an M2 and MJ preserved in the Megirian, Archer & Godthelp, 1998 holotype. Additional mystacinid material has since been Revised diagnosis. Speciesof Icarops differ from collected from another early Miocene deposit on Mystacina species in the following combination Riversleigh 's D Site Plateau,Judith 's Horizontalis of features:It width and length approximately equal Site. This material includes a mandible with fused (i.e. not especially wide); p 4 less than half MI dentaries containing the partial lower dentition length, with two roots oriented longitudinally or for a small species of Icarops. Based on only slightly obliquely with respect to the comparisonsof size and alveolar patterns,the new toothrow; all cusps of lower molars including material is referableto I. paradox. Icarops paradox entoconids taller and more distinct, with MI-2 is one of 44 species of fossil microchiropterans talonid wider than trigonid. recorded from Riversleigh's Oligo-Miocene and Pliocene limestone deposits (Archer et al. 1994, Other species. Icarops aenae Hand et al., 1998; Hand 1999). Icarops paradox Hand et al., 1998 In this paper, the new Icarops material is described and the diagnosis of the genus revised. Icarops paradox (Fig. lA-D) Taxonomy and dental terminology follows Miller (1907) and Hand et al. (1998). Stratigraphic Holotype. QMF20808, partial mandible preserving nomenclature for the Riversleigh region follows fragments of left and right dentaries with alveoli Archer et al. (1994) and Creaser(1997). The prefix forLI"C, andP.,andRC1,P,4andM,. Type localitY~ Neville's Garden Site, D Site evidence of crowding of teeth with overlapping Plateau, Riversleigh World Heritage Property, of the alveoli. Most of the crown ofP 4is broken Lawn Hill National Park, northwestern offbut it has two roots oriented slightly obliquely Queensland (Archer et al. 1994). with respect to the toothrow; the anterior alveolus is significantly smaller than the posterior one and New material. QMF31561, a partial, fused displaced towards the buccal margin of the mandible with left dentary preserving C1 and MI-3 toothrow. The anterior alveolus for MI is also and alveoli for I1 and p 24' and right dentary with slightly buccally displaced. broken p 4' MI-3 and associated RIl. The lower dental formula is 11'CI' P2.4' M123. The alveoli for the canines (but not the mciso"rs; Locality, age and lithology. Judith's Horizontalis contra Hand et at. 1998) are ventrally displaced Site, D Site Plateau,Riversleigh (seeCreaser 1997), with respect to the toothrow. The margins of the a freshwater limestone deposit interpreted as early canine alveoli are smooth and complete. The Miocene, based on stratigraphy and contained posterior alveolus of P4 is compressed by the local fauna {Archer et al. 1994: Creaser 1997). anteriorly inclined alveolus for the anterior root ofMI. The posterior alveolus for MI is larger than Associatedfauna. Other vertebrates recovered so the anterior one. far from the Judith 's Horizontalis Site include: RI1 was found within the jaw but was removed frogs, lizards, turtles, passerinebirds, bandicoots, during preparation of the mandible. It is relatively a marsupial mole, yalkaparidontid, burramyid large, and deeply and evenly trifid. The crown is possum, balbarid kangaroo, carnivorous not markedly extended backwards; its width and kangaroo, and a megadermatid bat (A. Gillespie, length are approximately equal. pers. comm.). Cl is simple in form; its posterior base has a small, rounded median cusp, marked by a small Revised diagnosis. Smaller than I. breviceps and notch for the anterior edge of P2. The basal I. aenae, and with P 2 larger and P 4 more cingulum is almost complete except at its most transversely oriented than in I. aenae (Hand et al. anterolingual point; its anterolingual edge has a 1998). Additionally, it differs from I. breviceps in distinct convexity just above the level of the MJ being less reduced (with trigonid and talonid incisors; here the cingulum is broken and of subequal width). connected to a short crest on the lower part of the crown. Description. The left and right dentaries of Most of the crown ofRP 4 is missing; the roots QMF31561 are completely fused, with no sign of remain. Judging from its alveoli and remaining the symphysis, and meet at an angle of crown, P4 was longer than P2 and less than half approximately 45°. The mandible's anterior the length ofMJ .Its two roots are oriented slightly margin, in lateral profile, is receding ventrally, obliquely with respect to the toothrow; the rounded and without a chin process. A ventral anterior alveolus is smaller than the posterior one mandibular shelf extends posteriorly to the and is close to the buccal margin of the dentary. alveolus for the anterior root of P4. A small but MI has two roots and five distinct cusps, the deep invagination in the shelf's posteroventral hypoconulid being a small cingular cusp. face marks the attachment point for the digastric Although individualised, the cusps appear muscle/s (in the holotype of I. paradox, relatively low and inclined rather than tall and QMF20808, the site for attachmentof the digastric upright. The trigonid is conspicuously narrower, muscles was not clear). The deI!tary decreasesin but approximately the same length as the talonid. depth only slightly from P2 to below the posterior The protoconid and hypoconid are the dominant root of MJ. The ascending ramus, condyle and cusps in height and volume, but they are not angular process are not preserved. massive. The protoconid is only just taller than Unlike other Icarops specimens(including the the hypoconid which is taller than the metaconid; holotype of I. paradox), there is no mental foramen the entoconid and paraconid are subequal in beneath P2 nor further posteriorly. There is, height; all are much taller than the hypoconulid. however, a small, dorsally directed foramen below The protoconid shows conspicuously more wear and betweenthe alveoli forC1 and 11.This foramen than the other cusps. The paracristid is just longer appearsto be homologous with that found in this than the metacristid; the protoconid contributions region in other Icarops specimens. The incisor to the paracristid and metacristid are longer than alveolar region is well preserved and contained a the paraconid and metaconid contributions; the single pair of incisors. The canine alveolus is large metaconid and protoconid contributions of the and oval. The single alveolus for Pis smaller than metacristid aremore equal and meet at a more acute the canine alveolus. As in the holotype, there is angle. The cristid obliqua, in occlusal view, is AAP Memoir 2 Fig. l.lcaropsparadox Hand, Murray, Megirian, Archer & Godthelp, 1998. QMF31561, from the early Miocene Judith's Horizontalis Site, Riversleigh World Heritage Property, Lawn Hill National Park, northwestern Queensland. A, lateral view; B, oblique occlusal view; C, stereopair, occlusal view. Scale bar indicates 2 mrn. v= ventral mandibular shelf. uncurved and contacts the trigonid at a point between the hypoconid and entoconid. A pre- directly below the junction of the components of entocristid, straight and steeply dipping, links the the metacristid. In lateral view there is an inflexion entoconid to the trigonid at the base of the along the cristid obliqua close to the trigonid. The metaconid