Cerberus schneiderii (Schlegel) Schlegel, 2012

Murphy, John C., Voris, Harold K. & Karns, Daryl R., 2012, The dog-faced water snakes, a revision of the genus Cerberus Cuvier, (Squamata, Serpentes, Homalopsidae), with the description of a new species, Zootaxa 3484, pp. 1-34 : 17-21

Cerberus schneiderii (Schlegel) new combination

Figure 8

Elaps boaeformis Schneider 1801 , 2:301. Type Locality: unknown. Collector: unknown. Holotype: unknown, presumed lost. Schlegel (1837:341) considered the name invalid and placed it the synonym of Homalopsis schneiderii . We consider this name nomen dubium.

Hurria Schneideriana — Daudin 1803b, 5: 281. Type Locality: None. Based upon Schneider's (1801) Elaps boaeformis , this name was considered invalid by Schlegel (1837: 341) and synonymized with Homalopsis schneiderii .

Homalopsis molurus — Boie 1826:213.

Python boaeformis — Merrem 1820:89. The specimen had 144+5 ventrals and 50 subcaudals. Merrem placed Schneider’s Elaps boaeformis and Daudin’s Hurria schneideriana in the synonymy of this name.

Cerberus Russelii Cuvier 1828 [fide Duméril, Bibron, Duméril 1854 7(ii): 979].

Homalopsis schneiderii Schlegel, 1837:341 . Lectotype: RMNH 1173. The lectotype designation is made here on the basis of the similarity of the scale patterns on the top of the head to the specimen illustrated in Schlegel’s Plate 13, Figures 6 and 7 (our Figure 9 ). Type Locality: Timor. Collector: Reinhardt.

Homalopsis rhinchops — Cantor, 1847:91.

Cerberus acutus Gray, 1849:65 . Type Locality: Borneo. Holotype: BMNH 1946.1.2.34. Cerberus unicolor Gray, 1849:65 . Holotype BMNH 1946.1.2.45. Type Locality: Philippines.

Cerberus rynchops – Bleeker 1857a:233; 1857c:242; Jan 1857:4; Gray 1858:273; Bleeker 1860:287; Giebel 1861:109; Günther 1863:58; 1864:279; Bocourt 1866:5; Steindachner 1867:67; Theobald 1868:57; Gervais 1869:79; West-Castelnau 1870:41; Günther 1872:590; Higgins 1873:34; Morice 1875:58;Theabold 1876:185; Müller 1878:605; Peters & Doria 1878:389; Müller 1880:149; Blanford 1881:215; Sales 1884:33; Tirant 1885:40; Boettger 1886:110; Cope 1886:494; Lidth de Jeude 1890:20; Sclater 1891:54; Boettger; 1892a:86; 1892b:124; 1893:3; Boulenger 1894a: 85; 1894b: 616; Müller 1894: 825; Boettger 1895: 132; 1898:88; Casto de Elera 1895:431; Bartlett 1896:101; Cope 1895:209; Boulenger 1896, 3:16; Flower 1896:888; Boulenger 1897a:201; 1897b:507; Bethencourt-Ferreira 1897:229; Boettger 1898:88; Flower 1899:679; Peracca 1899:327; Ridley 1899:208; Cope 1900:1115; Werner 1900:501; Boettger 1901:326; Grijs 1901:33; Laidlaw 1901:578; Schenkel 1901:166; Shelford 1901:64; Alcock & Rogers 1902:449; Lampe & Lindholm 1902:31; Boulenger 1903:175; Mocquard 1904:482; Annandale 1905:176; Rosén 1905:175; Wall 1905:307; Mocquard 1907:51; Stejneger 1907:305; Bedot 1909:147; Griffin 1909:599; 1910:213; Roux 1911:502; Boulenger 1912:163; Smith 1914:102; 1915:246; Gyldenstolpe 1916:19; Holtzinger-Tenever 1917:440; Rooij 1917:187; Phisalix & Caius 1918:939; Wall 1918:89; Robinson & Kloss 1920:303; Phisalix 1922, 2:285; Rooij 1922:218; Taylor 1922:111; Fejérváry 1923:167; Sarkar 1923:302; Sworder 1923:66; Werner 1923:162; Roux 1925:319; Dammerman 1926:323; Jong 1926:87; Kopstein 1926:109; Bourret 1927:241; Jong 1927:302; Kopstein 1927:443; Werner 1927:2; Jong 1928:151; Werner 1928:185; Gee 1929:73; Scortecci 1929:74; Brongersma 1929:67; Kopstein 1930:131; Mertens 1930a:152; Haas 1931:401; Kopstein 1931:1; Maki 1931:68; Smedley 1931:104; Brongersma 1933:15; Lloyd et al. 1933:19; Prater 1933:393; Bourret 1934:12; Brongersma 1934:200; Bourret 1936:295; Kopstein 1937:240; Bourrett 1939:23; Kopstein 1941:138; Smith 1943:393; Smith & Bellairs 1947:pl. 5; Laurent 1948:8; Haas 1950:578; Forcart, 1953:361; Liong 1953:127; Smith et al. 1953:260; Bergman 1955:113; Lim Boo Liat 1955:124; Wang & Wang 1955:1; Lim Boo Liat 1956:142; Tweedie & Reid 1956:1; Batchelor 1958:109; Hoesel 1958:32; 1959:92; Pfeffer 1959:195; Berry 1963:93; Taylor 1965:923; Dutt 1966:15; Hendrickson 1966:67; Macnae 1968:156; Campden-Main 1970:69; Gyi 1970:159; Singh et al. 1970:94; Gorman 1973:349; Mertens 1974:37; Saint Girons 1972a:125; 1972b:7; Heatwole 1975:147; Frith 1977:296; Minton 1975:22; Heatwole 1977:155; Dunson & Minton 1978:211; Heatwole & Seymour 1978:481; Dunson & Dunson 1979:661; Heatwole & Dunson 1987:289; Auffenberg 1980:120, fig. 39; Gorman et al. 1981:337; Supriatna 1982: 72; Tweedie 1983:102; Bosch 1985:17; Krishnan et al. 1985:119; Lillywhite 1985:307; Jayne 1986:915; Jayne et al. 1988:1; Welch 1988:49; Lim & Lee 1989:71; Price & Kelly 1989:247; Gaulke 1990:18; Cox 1991:186; Stuebing 1991:331; Giesen 1993:265; Lilley 1993:13; Weinstein & Kardong 1994:1161; Voris & Jefferies 1995:569; Brown et al. 1996:12; David &Vogel 1996:114; Iskandar & Nio 1996:46; Whittin et al. 1996:406; Manthey & Grossmann 1997:331; Cox 1998:39; Das 1998:46; Erdelen 1998:70; Gaulke 1998:140; Mori 1998:40; David & Ineich 1999:31; Stuebing & Inger 1999:90; Lim & Lim 1999:150; Karns et al. 2000:391; Pauwels et al. 2000:140; Chanhome et al. 2001:54; Ferner et al. 2001:42; Iskandar & Colijn 2001:219; Porej 2001:27; Karns et al. 2002:487; Auliya 2003:220; Fuchs & Fuchs 2003:232; Grismer et al. 2004:247; Alfaro et al. 2004:1277; Murphy 2007:72; Alfaro et al. 2008:578; Chim 2009:1.

Cerberus boaeformis — Bleeker 1857b:238, 1857c:473, 1858:262, 1860:287.

Hurria rynchops— Stejneger 1907:302; 1910:105; Taylor 1922:111; Barbour 1912:123; Prater 1923:159; Sworder 1923:66; Wall 1923:37; Sworder 1924:20; Wall 1924:867; 1925:817; Smith 1925:5; Raj 1927:183; Cochran 1930:30; Mertens 1930:210; 1957:30; 1959:9; Alcala 1986:143.

Comment. There are three names that could possibly become senior synonyms of Cerberus schneiderii : Elaps boaeformis Schneider 1801 , Boa moluroides Schneider 1801 and Coluber obtusatus Reinwardt 1823 . The first two names have published descriptions, with no collector or type locality given, the holotype of Elaps boaeformis is said to be in the University of Halle Museum (now the Central Magazine Naturwissenschaftlicher collection or CNS). And, the specimen of Boa moluroides was reportedly in the collection of the University of Jena’s museum (now the Phyletic Museum). The original description of this snake suggests it has 25 scale rows at mid-body, increasing the chances that it may in fact be C. rynchops . We have been unable to locate these specimens. Coluber obtusatus Reinwardt has apparently only been listed as a species in checklists, there appears to be no published description currently known and the name first appears in Schlegel (1837) but he apparently saw or had in his possession drawings made of live specimens by Reinwardt and placed it in the synonymy of Homalopsis schneiderii . Given the lack of artifacts and further knowledge of these three names, Schlegel’s Homalopsis schneiderii is the oldest available name for the Southeast Asian clade of Cerberus . Schneider’s two names and Reinwardt’s name become nomen dubia.

Schlegel examined specimens from Java eastward and considered Elaps boaeformis Schneider and Boa moluroides Schneider , Hurria schneideriana Daudin , Coluber obtusatus Reinwardt conspecific. At the same time he considered Coluber russelii Cuvier (= Hydrus rynchops Schneider ) a valid species. Thus, we are following Schlegel, pending evidence to the contrary.

Diagnosis. Cerberus schneiderii can be distinguished from all other members of the genus by its 23 (rarely 25) scale rows at midbody; the imbricate plate-like scales on the crown have a flat, thin appearance and lack keels anterior to angle of jaw; the last upper labial is horizontally divided; the venter is mottled. Cerberus australis has 23 scale rows at mid-body but the first upper labial does not contact the loreal (it usually does so in all other Cerberus species). Cerberus dunsoni has 23 scale rows at mid-body, but it has rounded juxtaposed scales on the crown, and a uniform black venter. Cerberus microlepis has 27–31 scale rows at mid-body. Cerberus rynchops usually has 25 scale rows at mid-body (rarely 23); the last two upper labials are horizontally divided (as opposed to one in C. schneiderii ).

A lectotype for Cerberus schneiderii ( Schlegel, 1837) . An examination of all RMNH specimens that were likely to have been examined by Schlegel when writing the Homalopsis schneiderii account based on collection date and collector were compared to his illustrations (Plate 13, Figures 6 and 7 ). They appear to illustrate RMNH 1173. Determination was made possible by the unique arrangement of the fragments of the frontal scale that are present in the drawing and the specimen ( Figure 9 ). Following article 74.4 of the International Code of Zoological Nomenclature 4th Edition (1999), thus, RMNH 1173 is designated as the lectotype of Homalopsis schneiderii Schlegel 1837 .

Description of the lectotype of Cerberus schneiderii . RMNH 1173, a female 867 mm TL with a 147 mm tail. Nasal scales in contact; internasal divided; frontal fragmented into small scales with two in the anterior row and three in the secondary row; ocular ring contains a single supraocular, a single preocular, two suboculars, and one postocular; upper labials 10/10, 1–4 contact the single loreal; eighth (last large) upper labial divided on both sides; lower labials 15/15; 1–4 contact first pair of chin shields on both sides; three pairs of chin shields; temporal formula 2+2/2+2. Dorsal scale rows 26/25/19; ventrals 148; subcaudals 51/51; anal plate divided. In alcohol, dorsal pattern faded but 18 cross bands are present on the anterior body; the ventral pattern is yellow with some dark mottling.

Variation. Largest male 839 mm TL, with a 156 mm tail; largest female 1075 mm TL with a 174 mm tail. Frontal scale fragmented; the largest remaining fragment is usually shorter than the supraocular [only two (2.6%) of 77 specimens examined for this trait had a frontal scale that was equal or longer than the supraocular scale – FMNH 202770, SM 0403]. Upper labials 1–3 or 1–4 in contact with the single loreal; last large upper labial horizontally divided. The first horizontally divided upper labial posterior to the eye is usually the ninth (83%), but can be the eighth (15%), tenth (1.3%) or seventh (0.6%). Of the 143 sides, 137 (96%) had one upper labial horizontally divided, and seven (4%) had two upper labials divided (only two specimens, FMNH 202780, FMNH 180289, have the last two upper labials divided on both sides, the character state found in rynchops ). Upper labials under the orbit (but separated by the subocular scales) 4+5, 5, 5+6, or 6; tallest upper labial (the largest) usually the eighth. Dorsal scales at midbody range from 20–27, but are usually 23–25 (73% of 123 specimens), occasionally they range from 20–22 (26.2% of 123 specimens), and rarely are they 27 (0.8%). Dorsal scales rows on anterior body 22–27, and at posterior body 17–20; scales keeled and striated, with the exception of the first row which usually shows no trace of keels; scales in the first row are usually slightly larger and more ovate than the rows tοwarđ the vertebral line• ventral scales are rοunđeđ anđ wiđe﹔ males I4 O—I7 O (n=58, x = I5 I•2), οnly 4 specimens (7%) have cοunts abοve I6 O ﹔ females I44 — I67 (n=65, x = I52 •5), but οnly 3 (4•6%) specimens have cοunts abοve I6 O ﹔ subcauđal 53—75 (n= 57, x =6 O) in males, 5O—62 (n=64, x = 55•8) in females• Τhe cοmpοsite data suggest little or no sexual dimorphism in this species; however when the data are broken down by specific locality most populations show sexual dimorphism in subcaudal counts (see Table 1).

In alcohol, dorsal surface of the head is uniform brown or gray with light upper and lower labials; a darker postocular stripe is often present; body dorsum is gray or brown with dark cross bands that extend onto the tail; Philippine population tends to have a uniform dorsum as do some specimens form elsewhere in the range; belly yellow or cream, sometimes extending onto the first two or three dorsal rows; venter may be uniform in color, or more often with dark blotches on the anterior margins of the ventrals and yellow or cream on the posterior margins of the ventrals, or it is mottled.

Figures

FIGURE 6. Lake Buhi Bockadam, Cerberus microlepis. USNM 197854. JCM.

FIGURE 7. The Karoo Bockadam, Cerberus rynchops. Photos by Aaron Lobo.

FIGURE 8. Schneider’s Bockadam, Cerberus schneiderii. Top: near Trang, Thailand; Bottom is from Pak Phanang, Thailand. Photos JCM.

FIGURE 9. The lectotype of Cerberus schneiderii (RMNH 1173) with the locality data – Timor. A and B compares the head scales of the lectotype to those in Schlegel’s drawing. The arrangement of the fragments of the frontal plate made it possible to identify this snake. C. Shows the lectotype in profile.