Myron richardsonii Gray, 1849

Murphy, John C., 2011, The Nomenclature And Systematics Of Some Australasian Homalopsid Snakes (Squamata: Serpentes: Homalopsidae), Raffles Bulletin of Zoology 59 (2), pp. 229-236 : 232-233

Myron richardsonii Gray, 1849

Type Locality: North Western Australia. Restricted here to Buffalo Creek, Northern Territory, Australia (about 12º40'S and 131º29'E) .

Holotype: QM J52861 . Type locality: Broome , Western Australia (about 17º58'S and 122º14'E).

1970 Myron richardsonii — Gyi, pages 172–174, Fig. 28.

Diagnosis. – A Myron with 19 scale rows on the neck and at mid body; one preocular scale; large, plate like occipital scales that are posterior and lateral to the parietals. M. resetari can be distinguished from M. richardsonii by its lower scale row count on the neck and at mid body (19 vs. 21); one preocular (two in M. richardsonii and M. karnsi ); and its largest upper labial is the 5 th compared with the largest upper labial of 6 or 7 in M. richardsonii . It can be distinguished from M. karnsi by the lower number of scale rows at mid body (19 vs. 21) and the blotched pattern on a gray ground color (as opposed to the black ground color and thin yellow crossbands of M. karnsi ).

Description of the holotype: On the head: rostral as broad as tall with the dorsal edge extending between the nasal scales; nasals are smaller than the diameter of the eye, separated by the internasal from the posterior edge and the rostral from Diagnosis. – A Myron with 21 scale rows on the neck and at mid body that are reduced to 17 or 19 rows near the vent; the posterior dorsal scale rows above row 6 are weakly keeled; two preocular scales; upper labials usually number 8 or 9; plate-like occipital scales located on the posterior edge of the parietals; 8 to 10 upper labials; and a dorsal pattern of blotches that number 35 to 48. The presence of 21 scale rows and two preoculars will distinguish it from M. resetari . The 8 to 10 upper labials and blotched pattern will separate it from M. karnsi which is melanistic with narrow yellow crossbands.

Eight males had 131–137 ventrals (x=133.8, sd=1.80) and 33–39 subcaudals (x=35.6, sd=1.76). Six females had 131–139 ventrals (x=135.5, sd=3.62) and five females had 30–34 subcaudals (x= 31.6, sd=1.82). While the ventral counts show no sexual dimorphism, the subcaudal counts based on this limited sample size most likely do.

Distribution. – Coastal northern Australia from the Gulf of Carpentaria to Western Australia and northward to the south coast of New Guinea.

A comparison of the three species of Myron can be found in Table 1.

Reassignment of Cantoria annulata . – Cantoria Girard, 1858 , was described on the basis of a specimen from Singapore. The type species is the morphologically distinctive Cantoria violacea Girard , the type species for the genus by monotypy. C. violacea has a long, slender body, dorsal scales in 19 rows at mid body; the ventral count ranges from 234–284, other scale characters are given in Table 2. C. violacea appears to prey exclusively on Alpheus shrimp in mangrove forests and their associated mud flats (Voris & Murphy, 2002). Molecular analysis found that Cantoria violacea is the sister to Gerarda and Fordonia ( Alfaro et al., 2008) , both crustacean–eating species with widespread coastal distributions.

Cantoria annulata Jong, 1926 was described from a specimen from Prins Hendrik-eiland, New Guinea which had 21 scale rows at mid body and ventral counts that range from 168–182. While C. annulata has its nasal scales separated by the internasal (as does C. violacea ), it also has the internasal in contact with the frontal scale, a character state unknown in other homalopsids. Given these differences and the others noted in Table 2, removing annulata from Cantoria is warranted, and here placed in a new genus.