Melanophryniscus pachyrhynus

Synonymy of Melanophryniscus pachyrhynus

Atelopus pachyrhynus. — Miranda-Ribeiro (1920). Type locality: "São Lourenço, S. Paulo", Brazil. Corrected to "São Lourenço no Rio Grande do Sul", Brazil, by Bokermann, 1966. Given as " Brazil, Rio Grande do Sul, São Lourenço do Sul (31 22S; 51 59W)" by Caramaschi and Cruz (2002). Syntypes (2 specimens): MZUSP 0752; MZUSP 0 756, designated lectotype by Caramaschi and Cruz (2002).

Atelopus pachyrhinus (unjustified emendation).— Miranda-Ribeiro (1926).

Dendrophryniscus tumifrons. —(nec Boulenger 1905) Müller (1934, partim).

Atelopus tumifrons. —(nec Boulenger 1905). Vellard (1947, partim).

Melanophryniscus tumifrons. —(nec Boulenger 1905) Gallardo (1961, partim). Bokermann (1966). Klappenbach 1968 (partim). McDiarmid (1971, partim). Braun and Braun (1980, partim). Frost (1985, partim). Gallardo (1987, partim). Prigioni and Langone ("1987 " 1986, partim). Garcia and Vinciprova (2003, partim).

Melanophryniscus pachyrhinus (unjustified emendation).— Lutz (1972). Céspedez and Motte (2001).

Melanophryniscus sanmartini. —(nec Klappenbach 1968) Klappenbach (1968, partim). Achaval and Olmos (1997, partim).

Melanophryniscus orejasmirandai. — Prigioni and Langone ("1987 " 1986), type locality: "Cerro de Animas (34°46’ S; 53°19’ W), 500 metros al NO. del Mirador Nacional, Departamento de Maldonado, Uruguay ". Holotype: MNHN 5476, by original designation. Kolenc (1987). Achaval (1989). Prigioni and Langone (1990). Echeverría (1992). Klappenbach and Langone (1992). Prigioni and Arrieta (1992). Langone (“1995” 1994). Duellman (1993). Maneyro et al. (1995). Achaval and Olmos (1997). Lavilla and Vaira (1997). Echeverría (1998). Evia and Gudynas (2000). Lavilla and Cei (2001). Maneyro and Langone (2001). Caramaschi and Cruz (2002). Achaval and Olmos (2003). Cruz and Caramaschi (2003). Haas (2003). Kolenc et al. (2003a). Kolenc et al. (2003b). Langone (2003). Larson et al. (2003). Baldo and Basso (2004). Langone et al. (2004). Manzano et al. (2004). Naya et al. (2004). Núñez et al. (2004). Kwet et al. (2005). Di-Bernardo et al. (2006). Achaval and Olmos (2007). Kolenc et al. (2007). Vera Candioti (2007). Maneyro and Kwet (2008). Langone et al. (2008). Stuart et al. (2008). Vaz-Silva et al. (2008). Ziegler and Maneyro (2008). Baldo et al. (2010). Bernardo-Silva et al. (2010). Canavero et al. (2010). Almeida-Santos et al. (2010). Bidau et al. (2011). Caramaschi and Cruz (2011). Dos Santos et al. (2011). Haad et al. (2011). Langone (2011). Baldo et al. (in press).

Melanophryniscus pachyrhynus. — Caramaschi and Cruz (2002). Cruz and Caramaschi (2003). Manzano et al. (2004). Borteiro et al. (2005). Kwet et al. (2005). Achaval and Olmos (2007). Kolenc et al. (2007). Colombo et al. (2007). Maneyro and Kwet (2008). Vaz-Silva et al. (2008, partim). Almeida-Santos et al. (2010). Canavero et al. (2010). Bidau et al. (2011). Caramaschi and Cruz (2011). Dos Santos et al. (2011). Haad et al. (2011). Lema and Martins (2011). Toledo et al. (2011).

Diagnosis. Melanophryniscus pachyrhynus can be diagnosed as follows: medium sized Melanophryniscus species (males = 22.15–30.36; females = 24.75–35.44); with a glandular swelling on snout; skin of dorsum granular, scattered with blunt, rounded, small to medium-size glandular warts; warts tipped with one to several keratinized spicules; dorsal color of head, body, and upper surfaces of appendages range from different brown tones to gray, with scapular region and swelling on the snout lighter; ventral surface of abdominal, pectoral and gular regions dark grey with an extensive orange reticulated pattern; some specimens with a gland on metatarsus of toes IV and V.

The presence of a glandular swelling on snout (putative synapomorphy of the Melanophryniscus tumifrons group, Baldo & Basso 2004), allows to easily distinguish M. pachyrhynus from all members of the M. stelzneri group: M. atroluteus (Miranda-Ribeiro), M. cupreuscapularis Céspedez & Álvarez, M. dorsalis (Mertens), M. estebani Céspedez, M. fulvoguttatus (Mertens), M. klappenbachi Prigioni & Langone, M. krauczuki Baldo & Basso, M. montevidensis (Philippi), M. paraguayensis Céspedez & Motte, M. rubriventris (Vellard), and M. stelzneri (Weyenbergh); of the M. moreirae group: M. langonei Maneyro et al., M. moreirae (Miranda-Ribeiro), and M. sanmartini Klappenbach; and from those species unassigned to any species group, M. admirabilis Di-Bernardo et al., M. alipioi Langone et al., and M. vilavelhensis Steinbach-Padilha. The glandular dorsal skin, with small to medium-sized glandular warts, tipped with one to several keratinized spicules, allow to distinguish M. pachyrhynus from M. cambaraensis and M. macrogranulosus (dorsal skin smooth, with big rounded glandular warts, warts with very few or without keratinized spines on tip). The general dorsal color pattern ranging from different brown tones to gray with scapular region and swelling on the snout lighter, distinguish M. pachyrhynus from M. cambaraensis and M. macrogranulosus (dorsum light bright to dark green), from M. simplex and M. tumifrons (dorsum homogeneously black to dark brown), and from M. spectabilis (background dark brown to black, with a distinct marbled pattern of sinuous yellow/orange stripes and two yellow/orange spots on scapular region).

The reticulated orange ventral pattern characteristic of Melanophryniscus pachyrhynus readily distinguish this species from M. cambaraensis and M. macrogranulosus (background dark green to gray, with big red spots on abdominal region, which can be extended to cover the entire ventral surface), from M. simplex and M. tumifrons (abdominal region with a large red patch that usually covers the posterior half of abdomen; anterior half of the abdomen and pectoral region dark brown to black, gular surface with three red or yellow blotches, one on the mental and two on subarticular regions), M. devincenzii (abdominal region with a big spot orange/red; pectoral and gular regions uniformly brown to black), and M. spectabilis (background dark brown with a big uniform orange spot on the abdominal region, with some small orange spots on the pectoral region, and with three yellow/orange spots on the gular surface, one on the mental and two on the subarticular regions, usually connected). Melanophryniscus pachyrhynus is most similar to the recently described M. peritus, which also apparently has a reticulated ventral pattern. The single known specimen of M. peritus is a female of 39.3 mm (Caramaschi & Cruz 2011), which is somewhat larger than known females of M. pachyrhynus, being this at present the only apparent difference between these species.

The subgroups of the Melanophryniscus tumifrons group defined by Caramaschi and Cruz (2002) associated M. pachyrhynus (and M. orejasmirandai) with M. spectabilis, and one of the proposed diagnostic characters was related to the ventral pattern. This grouping was not based on a phylogenetic analysis and since the particular orange ventral pattern is to date exclusive of M. pachyrhynus (and quite different from that observed in M. spectabilis), we prefer not to recognize the subgroups for the time being. Besides, we prefer to use the term glandular warts to tubercles (as defined by Lynch & Duellman 1997) based on available histological evidence (Delfino et al. 1998; Naya et al. 2004; Mebs et al. 2005).

Osteological remarks. McDiarmid (1971) indicated that the presence of nasal ornamentation would be characteristic of the genus Melanophryniscus. However, we found ornamentations (exostosis) only in species of the M. tumifrons group, including M. pachyrhynus. These ornamentations consist on small irregular ridges that underlie the frontal skin gland. Associated to this ornamentation, nasals are more convex transversally. We consider that nasal ornamentation most probably distinguishes species in the M. tumifrons group from the rest of the genus.

We noticed that the posterolateral processes of the hyoid plate described by Baldo and Basso (2004), Céspedez and Motte (2007), and Céspedez (2008) for different species of the Melanophryniscus stelzneri group could be the posterior lobe of the anterolateral processes, and that the posterolateral processes would be lacking as was previously described in other species of the genus (Trewavas 1933; Badenhorst 1945; McDiarmid 1971; 1972; present work). The anterolateral processes have a wide base with two lobes distally, one anterior and another posterior, which may be misidentified as being the posterolateral processes. The wide basis of the alary process of the hyoid (as hypobranchial I) was considered as a possible synapomorphy of the genus by Cannatella (1986) and also Graybeal and Cannatella (1995). Developmental studies would help to discern if the posterolateral processes of the hyoid plate are indeed not present or if they are fused with the anterolateral processes.

Geographic distribution. We reported in the present study five new localities for Melanophryniscus pachyrhynus, four of them in Rio Grande do Sul, Brazil (17.5 km northern from a Arroio Grande; Piratini; Viamão, Parque Saint-Hilaire; 22 km south from Encruzilhada do Sul), and one in southern Uruguay (Abra de Castellanos, Maldonado), see Appendix I and Figure 6. The examination of the specimens ZUFSM 3210–2 from Nova Roma (Rio Grande do Sul, Brazil) previously assigned to M. pachyrhynus by Vaz-Silva et al. (2008) showed that they are actually M. simplex. Melanophryniscus pachyrhynus occurs in the Uruguayan Savanna ecoregion, which is composed by extensive characteristic grasslands, palm savannas and gallery forests (Dinerstein et al. 1995). The habitat of this species consists of rocky open areas on top of hilly landscapes (Kolenc et al. 2003a; Vaz-Silva et al. 2008; present study).