Stegonotus heterurus Boulenger, 1893 :367

Kaiser, Christine M., Kaiser, Hinrich & O’Shea, Mark, 2018, The taxonomic history of Indo-Papuan groundsnakes, genus Stegonotus Duméril et al., 1854 (Colubridae), with some taxonomic revisions and the designation of a neotype for S. parvus (Meyer, 1874), Zootaxa 4512 (1), pp. 1-73 : 38-40

Stegonotus heterurus Boulenger, 1893:367

Taxonomic status. Valid.

Synonyms. None.

Original name. Stegonotus heterurus Boulenger, 1893:367 . George Albert Boulenger (1858–1937; Fig. 17E ) was a highly prolific Belgian-British naturalist associated for most of his professional life with the British Museum of Natural History. The species name heterurus is a word of Greek origin, combining “heteros” [different] and “oura” [tail] in reference to the fact that the subcaudal scales in this species are not paired, the character state in all species of Stegonotus known at the time of Boulenger’s description. The species description was presented in English. The image of Boulenger ( Fig. 17E ; reproduced under license no. 5449 from the National Portrait Gallery, London, United Kingdom) was taken in 1917 by the British portrait photographer Walter Stoneman (1876–1958).

Syntypes. BMNH 1946.1 .14.91 (formerly BMNH 83.3.17.13), 1946.1.14.95 (formerly BMNH 77.2.24.19), and 1946.1.15.10 (formerly BMNH 79.10.31.7), adult males ( Fig. 22 ) .

Type localities. The localities provided by Boulenger (1893) and in the specimen register at the BMNH for the type series of S. heterurus are, unfortunately, rather vague. Two specimens (BMNH 1946.1.14.95, 1946.1.15.10) are from “Duke of York Id.” [Duke of York Island, East New Britain Province, Papua New Guinea], whereas BMNH 1946.1.14.91 is from ” New Britain ” [the largest island in the Bismarck Archipelago, comprising East New Britain Province and West New Britain Province, Papua New Guinea]. Of these, Duke of York is the largest island of the Duke of York Islands, a group of relatively small islands (total land area 58 km 2), with maximum dimensions of 10 km in a north–south direction and 9 km in an east–west direction, and with a maximum elevation of ca. 110 m. In contrast, New Britain is a large (36,520 km 2) and topographically and ecologically diverse island (with a mountainous topography, especially in the eastern part of the island, featuring a highest elevation of nearly 2500 m), and can hardly be considered a “locality” in the strict sense.

Collection. Boulenger (1893) listed the Duke of York syntypes (BMNH 1946.1.14.95, 1946.1.15.10) as having been collected by “Rev. G. Brown,” who can be identified as the Methodist missionary George Brown (1835–1917; Fig. 17F ), a close friend of the novelist Robert Louis Stevenson of Treasure Island fame ( Anonymous 2018b). After an extended stint in Samoa, Brown spent a little over five years (1875–81) in the Bismarck Archipelago, arriving on Duke of York on 15 August 1875 at Port Hunter on the northern tip of the island ( Anonymous 2018b). Port Hunter provided the base of operations for expanding the territory of the mission to New Ireland and New Britain. The specimens of S. heterurus must have been collected during this 5-year period, but we have not been able to pinpoint a specific locality or date. The photograph of Brown ( Fig. 17F ; public domain) is the frontispiece of his autobiography ( Brown 1908).

The third syntype (BMNH 1946.1.14.91) was listed as having been received from the “Museum Godeffroy,” the collection of the Huguenot trader Johann Cesar VI Godeffroy (1813–1885) in Hamburg, Germany. The collection was established in 1861, and for the next two decades a variety of collectors were employed to expand its holdings. Only one of the known collectors, Franz Hübner (1846–1877), is listed as having specifically collected on New Britain ( Evenhuis 2007) during the years 1875–1877 ( Weidner 1967). During the museum’s operation, its curator Johann Schmeltz (1839–1909) compiled a series of sales catalogs, and it is likely that the specimen appeared in one of these catalogs and was purchased by the British Museum of Natural History.

Key characteristics of the type specimens. (1) BMNH 1946.1.14.91: O (364) mm SVL + O (108) mm TL = O (472) mm TTL. V ♂ = 188 (186), SC ♂ = 82 (83), SCR ♂ = 0.30 (0.31), D = O-17-O (17-17-15), SL E = 3+4 (3+4), SL = 7 (7), IL = O (8L 9R), IL G = 4 (4). (2) BMNH 1946.1.14.95: O (393) mm SVL + O (89) mm TL =O (482) mm TTL. V ♂ = 178 (179), SC ♂ = 81 (80), SCR ♂ = 0.31 (0.31), D = O-17-O (17-17-15), SL E = 3+4 (3+4), SL = 7 (7), IL = O (9), IL G = 4 (4). (3) 1946.1.15.10: 405 (477) mm SVL + 135 (135) mm TL = 540 (612) mm TTL. V ♂ = 182 (181), SC ♂ = 75 (76), SCR ♂ = 0.29 (0.30), D = O-17-O (17-17-15), SL E = 3+4 (3+4), SL = 9 (7), IL = O (O), IL G = 4 (4). It should be noted that the subcaudal counts in this species refer to subcaudal scales that span the entire width of the tail (i.e., unpaired subcaudals).

Key characteristics of the species. We have been able to examine 19 specimens of S. heterurus . Of these, 11 (2 ♀♀, 6 ♂♂, 3 unsexed) were collected on New Britain , six on New Ireland (1 ♀, 5 ♂♂), and two on Duke of York (2 ♂♂). Characteristics include V ♀ = 183–193 (189 ± 5.1), V ♂ = 179–198 (188 ± 5.2); SC ♀ = 83–93 (89 ± 5.5), SC ♂ = 76–88 (82 ± 3.9); SCR ♀ = 0.32, SCR ♂ = 0.30; D = 17-17-15 (100%); SL E = 3+4 (100%); SL = 7 (100%); IL = 8 (83%) or 9 (17%); IL G = 4. Regarding the frequency of IL, it should be noted that the percentages are based on one specimen with IL = 9 on both sides of the head, three specimens with a mix of IL = 8 or 9, and 13 specimens with IL = 8 on both sides of the head.

There does not appear to be any sexual dimorphism with respect to V and SC counts in S. heterurus , with values for SCR only minimally different. It is perhaps noteworthy that, unlike in any other species of Stegonotus , the females examined gave a higher maximum subcaudal count than males (93 in females, 88 in males), but this difference is within the standard deviation of the subcaudal count for either sex. The specimens of the original type series from Duke of York have the smallest values for relative tail length, and these are among the lowest for males in the entire genus. This is the only species in the genus other than S. florensis and S. sutteri that possesses entire subcaudal scales.

Comments. In order to anchor the name S. heterurus to a single specimen and stabilize the species, we hereby designate BMNH 1946.1.14.95 ( Fig. 22 A–E; Table 1) as the lectotype (Code, Article 74.7). It is the largest of the three syntypes , in an excellent state of preservation, and possesses the characteristics we consider diagnostic for the species. This means that the type locality for the species becomes restricted to Duke of York Island, and it renders BMNH 1946.1 .14.91 and 1946.1.15.10 as paralectotypes .

Given the very wide distribution of S. heterurus across New Britain and New Ireland, an archipelago generally known for its reptile diversity and endemism (e.g., Foufopoulos & Richards 2007; Richards 2011; Clegg & Jocque 2016), the presence of a single species of Stegonotus is perhaps surprising. This is especially noteworthy considering the recently unveiled endemism in the Raja Ampat Archipelago (Ruane et al. 2017) and the diversity we recognize for the Moluccas in this paper. Further research in these islands and the collection of new specimens would allow a molecular analysis to discern the genetic structure in this species and would, perhaps, uncover greater diversity.

Figures

FIGURE 17. Selected 19 th and 20 th Century authors and collectors of Stegonotus species. (A) Giacomo Doria (1840–1913), author of the species names aruensis and keyensis. (B) Odoardo Beccari (1843–1920), collector of the Stegonotus aruensis and S. keyensis type specimens. (C) William Macleay (1820–1891), author of the genus name Herbertophis and the species names darnleyensis and plumbeus. (D) John Archibald Boyd (1846–1926), collector of the Herbertophis plumbeus holotype. (E) George Albert Boulenger (1858–1937), author of the species names guentheri, heterurus, and reticulatus. Image licensed for use, © National Portrait Galley, London, United Kingdom. (F) The Reverend George Brown (1835–1917), collector of the Stegonotus heterurus syntypes from Duke of York Island. (G) Albert Stewart Meek (1871–1943), collector of the Stegonotus guentheri and S. reticulatus syntypes. (H) Wilhelm Adolfovich Lindholm (1874–1935), author of the species name diehli. (I) Nelly de Rooij (1883–1964), author of the species name florensis. (J) Franz Werner (1867–1939), author of the species names dorsalis and poechi. (K) Rudolf Pöch (1870–1921), collector of the Stegonotus dorsalis and S. poechi holotypes, and in whose honor the latter was named. (L) Lothar Forcart (1902–1990), author of the species name sutteri.

FIGURE 22. Type specimens of Stegonotus heterurus Boulenger, 1893. Photos include views of the entire body of the lectotype BMNH 1946.1.14.95, an adult male (TTL = 482 mm) in (A) dorsal and (B) ventral views, and of the specimen’s head in (C) dorsal, (D) right lateral, and (E) ventral views. The heads of the paralectotypes BMNH 1946.1.14.91 and 1946.1.15.10 are shown in dorsal (F,I), right lateral (G,J), and ventral (H,K) views, respectively.