Platypelis tetra

Abstract

Comparative osteology of Platypelis tetra Based on micro-CT scan of paratype ZSM 42/2011 (originally MRSN A2172) and holotype MRSN A2174 (Fig. 7). Despite scanning artefacts and broken bones (MRSN A2174 has major post-mortem fractures to the ilia, the left femur, the left tibiofibula, the left radioulna, and the proximal phalange of the third toe of the left foot; it also has a developmental error in its presacral vertebra VIII, with the left transverse process developed as a broadened sacrum-like diapophysis), the following features are noted to differ from the specimen of P. efatra sp. nov. described above (they may constitute further diagnostic differences between the species, but this requires confirmation from analysis of more individuals per species): the zygomatic ramus of the squamosal is shorter than the otic (vs. longer in P. efatra) and less curved. Palatal bones are much less ossified and comparison of their anatomy is challenging. Coracoids much less flared medially, being only 1.5 times broader than at the glenoid socket. Presacral vertebrae VII and VIII with transverse processes oriented more laterally. Anterior edge of sacrum almost perpendicular to body axis (vs. angled anteriorly). Urostyle with dorsal crest <50% of its length (vs ≥50%). Dorsal prominence on iliac shafts and oblique groove indistinct (vs. well developed and distinct; although both ilia of the holotype MRSN A2174 are broken at this point). Advertisement calls of Platypelis tetra Although we were unable to record advertisement calls of the new species for comparison, we here provide an updated description of the advertisement calls assigned to P. tetra which we think will be useful for future taxonomic studies of the P. tetra complex. The advertisement call recorded on 3 April 2010 at Ambodivoangy (estimated air temperature 26°C) constists of a very short tonal note repeated in long call series (duration of call series up to>30 s) at somewhat irregular intervals (Fig. 8). Each call shows some very slight amplitude modulation with maximum call energy present in the first third of the call’s duration. Frequency is distributed in a rather narrow band. Numerical parameters of 53 calls of two males analyzed are as follows: call duration (= note duration) 8–13 ms (10.3 ± 1.3 ms); inter-call interval within call series 227–460 ms (311.7 ± 54.9 ms); dominant frequency 5071–5201 Hz (5149 ± 53 Hz); prevalent bandwidth 4500–5600 Hz. Within regular call series, calls were repeated at an approximate rate of 190–200 calls/minute. Calls recorded on 5 February 1996 at the type locality in Anjanaharibe Sud Special Reserve (air temperature 18.0‒18.5°C) in general character, are in agreement with those reported from Ambodivoangy, but differ by slightly longer call duration and lower dominant frequency (Fig. 8). Numerical parameters of 50 calls of one male analyzed are as follows: call duration (= note duration) 14–20 ms (16.5 ± 1.7 ms); inter-call interval within call series 241– 281 ms (261.7 ± 11.1 ms); dominant frequency 3953–4083 Hz (4029 ± 45 Hz); prevalent bandwidth 3500–5000 Hz. Within regular call series, calls were repeated at an approximate rate of 215 calls/minute. Conservation status of Platypelis tetra and P. efatra Platypelis tetra is currently considered as Endangered according to the Red List of the International Union for Conservation of Nature (IUCN SSC Amphibian Specialist Group 2016), based on the assumption that its extent of occurrence (EOO) is 4,759 km 2, spanning a severely fragmented habitat, occurrence in two threat-defined locations, and the ongoing decline in the extent and quality of its habitat in northeastern Madagascar. We here have added a few additional records which, however, did not result in a substantial range extension for the species. Furthermore, our genetic evidence indicates that several of the populations currently assigned to the species may in fact represent other, yet undescribed taxa. Therefore, the current status as Endangered appears to be reasonable. For P. efatra, a similar rationale as for P. tetra can be applied. The species is currently known from only three threat-defined locations, its EOO is comparable if not smaller than that of P. tetra, and there is ongoing decline in the extent and quality of its habitat which in part is outside of effectively protected areas. For a future Red List assessment of this species, a status as Endangered may therefore be appropriate.