Calophrynus calcaratus Mocquard, 1895

Scherz, Mark D., Schmidt, Luca, Crottini, Angelica, Miralles, Aurélien, Rakotoarison, Andolalao, Raselimanana, Achille P., Köhler, Jörn, Glaw, Frank & Vences, Miguel, 2021, Into the Chamber of Horrors: A proposal for the resolution of nomenclatural chaos in the Scaphiophryne calcarata complex (Anura: Microhylidae), with a new species-level phylogenetic hypothesis for Scaphiophryninae, Zootaxa 4938 (1), pp. 392-420 : 408

Calophrynus calcaratus Mocquard, 1895

Name-bearing type: Lectotype by present designation, MNHN 1895.294 , from “ Madagascar ” according to the original description.

Originally, there were four syntype specimens under the number 95.294 (= MNHN 1895.294 ), of which three were re-catalogued as MNHN 1991.2862 , MNHN 1991.2863 and MNHN 1991.2864 (now paralectotypes) .

Historically, this is the second described species assignable to the subgenus Pseudohemisus , and unfortunately only has the imprecise type locality “ Madagascar ”. The original syntypes are in an extremely poor state of preservation and probably juveniles. Due to the lack of clear morphological distinctions between the lineages within the S. calcarata complex, it is not possible to unambiguously define to which of these the name calcarata should apply on the basis of morphology or biogeography.

The largest of the original syntypes is the one that originally bore the number “95.294”. SVL of the four specimens is as follows: MNHN 1895.294 : 13.7 mm ( Table 1) ; MNHN 1991.2862 : 11.8 mm ; MNHN 1991.2863 : 9.8 mm ; MNHN 1991.2864 : 8.7 mm. We here designate the largest specimen , MNHN 1895.294 , as lectotype to stabilize this nomen because a few more taxonomically relevant morphological characters are visible in this specimen than in the others .

Morphology. Despite its small size and extremely poor state of preservation, the lectotype can easily be recognized as belonging to Scaphiophryne by the presence of an enlarged inner metatarsal tubercle and a distinct tarsal tubercle ( Fig. 9 ). No traces of vomerine or maxillary teeth are recognizable, but the anterior region of the head is largely destroyed, so this remains inconclusive. The subarticular tubercle on the first finger is slightly longer and higher than those on the other fingers. There are no enlarged terminal disks on fingers or toes.

Determining osteological characters of this specimen proved exceptionally difficult because its skeleton is largely destroyed and fragmented, especially the skull, which is highly disarticulated and has several elements missing altogether ( Fig. 10 ). Nevertheless, there is some osteological support for its identification as a scaphiophrynine microhylid, such as the T-shaped squamosal, diplasiocoelous vertebral column, terminal phalanges of fingers and toes robust and knobbed and not T-shaped, and pectoral girdle without ossified sternum and omosternum but with ossified clavicles (Supplementary Figs S2–S 3 ).

Assignment. Due to the lack of precise information on the geographical provenance of these specimens, assigning them to a particular lineage of the subgenus Pseudohemisus is not straightforward. First of all, we considered whether the types of Calophrynus calcaratus could be conspecific with the lineage usually named Scaphiophryne brevis . Blommers-Schl̂sser & Blanc (1991) noted that the subarticular tubercles in S. brevis are flat whereas in S. calcarata they are protruding. In the calcaratus lectotype they are rather protruding, as already stated in the original description. Furthermore, and more importantly, on the left side of the lectotype the boundary between the dorsal and lateral skin is folded in a way that may correspond to the dorsolateral fold typical for those specimens usually assigned to S. calcarata , but not for most of those assigned to S. brevis . We therefore conclude that the lectotype of Calophrynus calcaratus belongs to one of the evolutionary lineages herein subsumed in the S. calcarata complex ( Fig. 1 ).

To decide to which of these lineages the lectotype belongs, we can only apply a combination of arguments of historical plausibility and nomenclatural stability. We have already assigned the older nomen obscurus to the lineage occurring in north-western and western Madagascar. The range of the second lineage occurring in southern Madagascar includes several well-sampled sites such as Tolagnaro and Toliara. The original type series of Calophrynus calcaratus was collected by Grandidier who is known to have collected in the area (Betsileo) where the southern lineage is known to occur (e.g., Ambalavao, Anja, Isalo). In addition, the publication by Mocquard (1895), which includes the description of Calophrynus calcaratus , also features descriptions of several other species originating from Betsileo. Therefore, we propose to apply the name Scaphiophryne calcarata ( Mocquard, 1895) to the southern lineage in the S. calcarata complex, i.e., to the form called Scaphiophryne calcarata B in Glaw & Vences (2007) and Scaphiophryne sp. 1 in Vieites et al. (2009). Besides being plausible based on what is known of Grandidier’s collections, this taxonomic proposal also has the advantage of largely preserving the prevalent use of this name.

Figures

FIGURE 1. Majority-rule consensus tree from a partitioned Bayesian Inference analysis of species of Scaphiophryne, based on concatenated DNA sequences of five mitochondrial and two nuclear genes (3574 bp). Numbers at nodes are Bayesian posterior probabilities (removed from most terminal nodes for better visualization). The root was set at the branch connecting Paradoxophyla and Scaphiophryne, which are well-defined monophyletic units, and sister genera based on previous analyses (e.g., van der Meijden et al. 2007; Tu et al. 2018; Streicher et al. 2020).

FIGURE 2. Haplotype networks based on DNA sequences of two nuclear genes, POMC (310 bp) and RAG-1 (788 bp) for species of Scaphiophryne and Paradoxophyla. Small black circles represent additional mutational steps between identified haplotypes. Colors of taxa correspond to those in Fig. 1.

FIGURE 3. Individuals in life of the three species of Scaphiophryne in the subgenus Pseudohemisus according to the classification proposed in the present paper: Scaphiophryne brevis from Ifaty (A–E), Kirindy (F–G) and Isalo (H); S. calcarata from Pic St. Louis near Tolagnaro (I–K), Ambalavao (L), Isalo (Ilakaka) (M–N), Sakaviro (O) and near Anja (P); S. obscura from Isalo (Q), Kirindy (R–V), Ankarafantsika (W), and Bongolava Plateau (X). Photos by F. Glaw, J. Lobon-Rovira, A. Miralles, G. M. Rosa, and M. Vences.

FIGURE 9. Photographs of the details of morphology of type specimens of the nomina in the genus Scaphiophryne (subgenus Pseudohemisus) except the holotype of S. brevis, showing feet (left column) and hands (middle column) in ventral view, and the head (right column) in lateral view.

FIGURE 10. Micro-CT scans of the name-bearing type specimens of nomina in the subgenus Scaphiophryne (Pseudohemisus) except the holotype of S. brevis: skulls in dorsal, ventral and lateral views.