Alcalus, Brown & Siler & Richards & Diesmos & Cannatella, 2015

Brown, Rafe M., Siler, Cameron D., Richards, Stephen J., Diesmos, Arvin C. & Cannatella, David C., 2015, Multilocus phylogeny and a new classification for Southeast Asian and Melanesian forest frogs (family Ceratobatrachidae), Zoological Journal of the Linnean Society (Zool. J. Linn. Soc.) 174 (1), pp. 130-168 : 142

ALCALUS GEN. NOV.

Type species

Micrixalus mariae Inger 1954 .

Diagnosis

Members of the genus Alcalus can be distinguished from many members of the clade Anurajen (species of the genera Cornufer and Platymantis ) by having (1) an intermediate body size ( Al. baluensis : males 20– 25 mm Snout-Vent Length (SVL), females 26–31; Al. mariae : males 32–37 mm SVL, females 35–43); (2) a broad head (vs. slender to moderately broad); (3) a coarsely textured, shagreened, or ‘wrinkled’ skin appearance in all species (vs. smooth, tuberculate, or with longitudinal dorsolateral dermal ridges); (4) widely expanded, terminally squared, spatulate toe discs (vs. non- or minimally expanded, terminally rounded); (5) semi-aquatic microhabitat preferences (vs. preferences for terrestrial or arboreal microhabitats in most species); and by the (6) presence of nuptial pads in males (vs. absence); (7) absence of vocal sacs (vs. presence of median subgular vocal sacs); (8) absence of supernumerary tubercles on hand (vs. presence in most species); (9) presence of elongate subarticular tubercles (vs. presence, round); (10) absence of outer metatarsal tubercles on plantar surface of feet (vs. presence in most species); and (11) presence of extensive, usually full, interdigital webbing of the feet (vs. absence).

Phylogenetic definition

Alcalus (NCN) is a maximum crown-clade name that refers to the crown clade (C) originating in the last common ancestor of Al. mariae and all extant species that share a more recent common ancestor with Al. mariae than with Cornufer vitiensis or Platymantis corrugatus . It can also be conceived of as the largest crown clade containing Al. mariae , but not Co. vitiensis or Pl. corrugatus .

Content

Southeast Asian (Sunda Shelf and Palawan Island) species formerly placed in Ingerana ( Table 3): Al. mariae , Al. baluensis , Al. rajae , and presumably Al. sariba (Shelford, 1905) , which was not sampled ( Table 3).

Comment

It is not surprising that the montane, semi-aquatic, Southeast Asian island archipelago species formerly referred to Ingerana comprise a monophyletic group, unrelated to the ecologically dissimilar and biogeographically disjunct mainland species of Ingerana (as presently understood, from Andaman Islands, Bhutan, China, north eastern India, Myanmar, and Nepal). Erection of a new genus to accommodate these taxa is undertaken here with reference to the phylogenetic placement of the type species of ‘true’ Ingerana ( I. tenasserimensis ), which in our phylogeny is more closely related (but with weak support) to the Dicroglossidae than to the Ceratobatrachidae ( Fig. 2). The placement of Alcalus as the sister group of the clade Anurajen (containing genera Platymantis and Cornufer ) has been confirmed elsewhere ( Bossuyt et al., 2006; Frost et al., 2006; Wiens et al., 2009; Pyron & Wiens, 2011), although taxon sampling was not as extensive. The phylogenetic relationships and possible additional generic subdivision of the nonceratobatrachid (perhaps dicroglossid) species referred to Ingerana remain unstudied.

Etymology

A masculine noun honouring our long-term collaborator, friend, and mentor Angel C. Alcala for his numerous contributions to the systematics, ecology, conservation, and developmental biology of Southeast Asian amphibians. Suggested common name: Alcala’s dwarf mountain frogs.