Siagonodon septemstriatus (SCHNEIDER, 1801)
Can you confirm these amateur observations of Siagonodon septemstriatus?
|Higher Taxa||Leptotyphlopidae, Epictinae, Epictini, Typhlopoidea, Serpentes, Squamata (snakes)|
|Common Names||E: Seven-striped Blind Snake|
Portuguese: Cobra-Cega, Fura-Terra
|Synonym||Anguis septem-striatus SCHNEIDER 1801: 341|
Leptotyphlops tatacua BRICENO-ROSSI 1934
Typhlops senptemstriatus WAGLER 1830: 196 (lapsus)
Catodon septem-striatus — DUMÉRIL & BIBRON 1844: 319
Stenostoma (Catodon) septemstriatum — JAN 1860
Siagonodon septemstriatus — PETERS 1881
Glauconia septemstriata — BOULENGER 1893: 71
Leptotyphlops septemstriatus — MERTENS 1925: 78
Leptotyphlops tatacua BRICENO-ROSSI 1934
Leptotyphlops septemstriata — BEEBE 1946: 13
Leptotyphlops septemlineata HOFFSTETTER & GASC 1969 (lapsus)
Leptotyphlops septemstriatus — STARACE 1998: 79
Leptotyphlops septemstriatus — MCDIARMID, CAMPBELL & TOURÉ 1999: 42
Leptotyphlops septemstriatus — GORZULA & SEÑARIS 1999
Siagonodon septemstriatus — ADALSTEINSSON, BRANCH, TRAPE, VITT & HEDGES 2009
Siagonodon septemstriatus — WALLACH et al. 2014: 666
Siagonodon septemstriatus — NOGUEIRA et al. 2019
|Distribution||N Brazil (Para, Amazonas, Roraïma), Guyana, French Guiana, SE Venezuela, Bolivia|
Type locality: unknown (fide KORNACKER 1999).
|Types||Holotype: RMNH (type status and ID uncertain, fide E. Dondorp, pers. comm., 28 Jan 2019; a specimen of Typhlophis squamosus in RMNH has a hand-written note saying that it may be Typhlops septemstriatus or its type).|
|Diagnosis||Diagnosis (genus): Species of Siagonodon have 14 midbody scale rows, 10–14 midtail scale rows, 206–289 middorsal scale rows, 8–20 subcaudals, two supralabials, small or moderate or large anterior supralabials, 202–300 mm maximum adult total length, a body shape of 39–130 (total length/width), a relative tail length of 2.1–6.6%, a tail shape of 1.3–2.6, striped pattern, multiple dorsal colors, and white venter (Table 2). They also lack a supraocular scale. The absence of a supraocular scale distinguishes this genus from the other genus in the subtribe, Epictia (except E. nasalis). Other traits distinguishing the two genera show overlap, but species of Siagonodon tend to have fewer midtail scale rows and a white venter (Table 2). Only one species of this genus was sequenced (from ADALSTEINSSON et al. 2009).|
Diagnosis (genus). Members of the genus Siagonodon can be distin- guished from other genera of Leptotyphlopidae by unique combination of the following characters: supralabial scales two (1þ1); infralabial scales three or four; rostral scale and terminal spine uniformly colored; rostral scale with enlarged base; terminal spine reduced or absent; snout straight in lateral view; belly unpigmented; tail relatively shorter compared to species from other genera with the same total length (TL/TAL: 2.2–4.7); dorsal scales 163–299; ventral scales 160–286; subcaudal scales 9–16; midtail scales 10–14 [Francisco et al. 2018].
Comparisons with other Neotropical genera. Members of the genus Siagonodon differ from those of Rena and Trilepida (character states in parentheses) by having a straight snout in lateral view (vs. round or truncate snout; Fig. 2), enlarged rostral base (vs. narrow rostral base; Fig. 3), and caudal spine conspicuously reduced or absent (vs. caudal spine enlarged; Fig. 4). Species of Siagonodon are distinguished from those of Epictia (character states in parentheses) by having rostral scale and caudal spine with uniform color (vs. several species with yellow or white blotches at the end of the tail, including caudal spine), straight snout in lateral view (vs. rounded snout), unpigmented ventral surface of body (vs. venter with stripes or blotches, usually black), rostral scales in adults of Siagonodon ranging from 36–56% (47,164; n = 50; CL: 45.9– 48.2) of total head width (vs. 14.9–41.6% [2967.16; n = 49; CL: 26.9–31]), constituting a significant statistical difference (U = 17; P , 0.01); ratio TL/TAL in adults of Siagonodon ranging from 2.2 to 4.7 (3.760.53, n = 50; CL: 3.5–3.8; vs. 3.8 to 7.2 (5.860.85, n = 49; CL: 5.5–6), also representing a significant statistical difference (U = 74.5; P , 0.01) [Francisco et al. 2018].
See Francisco et al. 2018: Table 1 for meristic data in the genus.
|Comment||Type species: Anguis septem-striatus SCHNEIDER 1801 is the type species of the genus Siagonodon PETERS 1881.|
Synonymy: Mertens (1925) placed the genus Siagonodon in the synonymy of Leptotyphlops Fitzinger (1843)
Distribution: see Martins et al. 2020: 852 (Fig. 12) for a map of all 4 Siagonodon species, the sister clade of Habrophallos. See map in Nogueira et al. 2019.
|Etymology||Etymology (genus): The generic name is masculine and derived from the Greek nouns siagon (jaw) and odon (tooth), probably in allusion to the presence of teeth only on the lower jaw.|