Chalarodon madagascariensis Peters, 1854

Miralles, Aurelien, Glaw, Frank, Ratsoavina, Fanomezana M. & Vences, Miguel, 2015, A likely microendemic new species of terrestrial iguana, genus Chalarodon, from Madagascar, Zootaxa 3946 (2), pp. 201-220 : 203-204

Identity of Chalarodon madagascariensis Peters, 1854 and designation of a lectotype

The original description of Chalarodon madagascariensis by Peters (1854: 616) is extremely short, but in a later publication the same author provided further details and a figure ( Peters 1882: 32) and stated that the original collection consisted of ten specimens from the Bay of St. Augustin. All of these were of small size although the species was expected to grow significantly larger. Of the ten syntypes, a minimum of six have been traced by Bauer et al. (1995: 58): “ZMB 4360 (2 specimens), 5617, 9214 (2 specimens), MNHN 270 (fide Brygoo [1989]); BMNH?? (fide Boulenger [1885]).” In the meantime, one of the two specimens with the number ZMB 4360 was renumbered to ZMB 69147, one of the two specimens with the number ZMB 9214 was renumbered to ZMB 69144, and the formerly overlooked skeleton ZMB 13569 was identified as an additional syntype, whereas ZMB 5617 is currently missing from the collection (F. Tillack, pers. comm. 27. Jan. 2015). As indicated by Bauer et al. (1995) one syntype has been exchanged with the Muséum nationale d'Histoire naturelle at Paris and now bears the number MNHN 270 (see Brygoo 1989). According to the VertNet database (accessed on 27 Jan. 2015), MNHN- RA-0.270 was collected by Peters, but the locality of this specimen is given as “Sans localité précise” and its status as syntype is not indicated. It is apparently the only Chalarodon specimen present in the MNHN collected by Peters and therefore should be considered as syntype. One of the syntypes was exchanged with the collection of the Natural History Museum in London ( Boulenger 1885: 128). Altogether, the list of syntypes according to current knowledge includes eight specimens: (1) ZMB 4360; (2) ZMB 5617 (missing from collection); (3) ZMB 9214; (4) ZMB 13569 (skeleton); (5) ZMB 69144 (ex 9214); (6) ZMB 69147 (ex ZMB 4360); (7) MNHN 0.270; (8) one syntype in BMNH (number unknown).

Four of the syntypes (ZMB 4360, ZMB 9214, ZMB 69147, ZMB 69144) were available for our study, and as was expected from the work of Peters (1882) are all juveniles. The following account refers exclusively to these four ZMB syntypes examined by us. All are in relatively poor state of preservation, thus only basic data (not included in table 3) are given. The four specimens are characterized by distinctly keeled ventral and gular scales and in all of them six scales are in contact with the mental, thereby confirming the differences to the new species described below. The four specimens are characterized as follows:

(1) ZMB 4360: SVL 42.9 mm, tail 68.3 mm (almost complete), two strongly enlarged flat scales ventrally on tail base posteriorly to the cloaca, therefore probably a juvenile male.

(2) ZMB 9214: SVL 36.0 mm, tail 18.2 (mutilated), no strongly enlarged flat scales ventrally on tail base posteriorly to the cloaca, therefore probably a juvenile female.

(3) ZMB 69144: SVL 37.0 mm, tail 34.8 (tail tip mutilated and remaining tail broken into two pieces), no strongly enlarged flat scales ventrally on tail base posteriorly to the cloaca, therefore probably a juvenile female.

(4) ZMB 69147: SVL 39.0 mm, tail ca. 68.7 mm (tail complete but almost broken at one point), belly ventrally opened, two strongly enlarged flat scales ventrally on tail base posteriorly to the cloaca, therefore probably a juvenile male.

Although the four syntypes examined are morphologically uniform, and the entire series was reported to originate from the same locality, we cannot exclude that any of the six syntypes not examined by us might turn out to belong to the new species below, or to yet another, still undiscovered taxon. Hence, considering the existence of at least two Chalarodon species and the unknown fate of several syntypes it appears important for taxonomic stability to define a single name-bearing type for C. madagascariensis . Following this rationale, we hereby designate ZMB 4360 as lectotype ( Fig. 1 ). This is the largest of the four studied syntypes, has a nearly complete tail, a darkened throat, and is in the relatively best state of preservation. It therefore is taxonomically the most informative specimen. See Figure 1 for a photograph of the lectotype.

Figures

FIGURE 1. Designated lectotype of Chalarodon madagascariensis (ZMB 4360) in (A) dorsal and (B) ventral view.