Letheobia caeca (DUMÉRIL, 1856)
Can you confirm these amateur observations of Letheobia caeca?
|Higher Taxa||Typhlopidae (Afrotyphlopinae), Typhlopoidea, Serpentes, Squamata (snakes)|
|Common Names||Gabon Beaked Snake|
|Synonym||Onychocephalus caecus DUMÉRIL 1856: 462|
Typhlops coecus — JAN 1864
Letheobia caeca — COPE 1868: 322
Typhlops acutirostratus ANDERSSON 1916: 23
Typhlops caecus caecus — WITTE 1961
Rhinotyphlops caecus — ROUX-ESTÈVE 1974: 210
Rhinotyphlops caecus — MCDIARMID, CAMPBELL & TOURÉ 1999: 79
Letheobia caecus — WALLACH 2005
Letheobia acutirostratus — WALLACH 2005
Letheobia acutirostratus — BROADLEY & WALLACH 2007
Letheobia caeca — BROADLEY & WALLACH 2007
Letheobia caeca — HEDGES et al. 2014
|Distribution||Gabon, Ghana, W/C/E Democratic Republic of the Congo (Zaire), Congo (Brazzaville), Cameroon|
Type locality: "Gabon."
|Types||Syntypes: MNHN 1063 and MNHN 1063A.|
|Diagnosis||Diagnosis (genus): Letheobia is comprised of the clade stemming from the most recent common ancestor of Typhlops leucostictus and the Rhinotyphlops newtonispecies group. This includes Roux-Estève’s (1974) Typhlops Groups II and V plus hinotyphlops Groups IV, V, VI and VII, which is equivalent to the Letheobia clade of species examined by Wallach 1998 (PhD thesis, Northeastern University, Boston). For an alternative diagnosis see PYRON & WALLACH 2014: 50.|
Diagnosis (genus). Species of Letheobia have (1) eye, indistinct, (2) snout, beaked or rounded, (3) head scale arrangement, non-circular, (4) frontorostral, absent, (5) nasal, completely or incompletely divided, (6) nasal suture origin, 2nd supralabial (rarely, 1st supralabial, suture (1/2), rostral, or preocular), (7) suboculars or subpreoculars, present (rarely absent), (8) postoculars, 3–4 (rarely 2, 5–7; average, 3.55), (9) preocular-labial contact, supralabials 2 & 3 (sometimes 2nd, 3rd, 2–4, or none), (10) midbody scale rows, 18–30 (average 22.3), (11) scale row reduction, present or absent, (12) total scale rows, 250–737 (average, 484), (13) caudals, 8–15 (average, 11.1), (14) maximum total length, 135–670 (average, 350) mm, (15) total length/midbody diameter, 35–129 (average, 66.6), (16) total length/tail length, 45.5–143 (average, 79.0), (17) dorsal color, usually pale (pink, cream, white, colorless), (18) ven- tral color, usually pale (pink, cream, white, unpigmented), (19) dorsum same color as venter, and (20) overall, a
patternless, unicolor snake (Tables 1–2); molecular phylogenetic support (Fig. 1).
From Afrotyphlops and Rhinotyphlops, Letheobia is distinguished by having an indistinct eye (versus distinct), having subocular scales present (versus absent), and having a pale (versus dark) dorsum. [HEDGES et al. 2014: 30]
Characters: The nomenclature of supralabial imbrication patterns (SIP) follows Wallach (1993), except that “X” indicates no supralabial overlaps a superior head shield, II–P amd II–O indicate second supralabial overlapping preocular and ocular, respectively, and S and PO represent the subocular and postocular, respectively. Scale rows were counted as follows: mid-dorsals (MD) between the rostral shield and the apical spine; longitudinal scale rows (SR) at three points: first (A) at level of 20th midventral scale caudad of mental; second (B) at midbody (MSR) and third (C) at 10th scale craniad of vent. Scale row reductions between points A–B and B–C were then recorded. The ratios of middorsals/vertebrae (MD/V from Roux-Estève 1974) and total length/midbody diameter (L/D) were calculated.
The western population (L. caecus) from Nigeria, Cameroon, Gabon and Congo-Brazzaville has 22 scale rows, a papillate rostral shield, and supranasals extending beyond the rostral. The eastern population (L. acutirostratus Andersson 1916) from the Democratic Republic of the Congo has 24-26 scale rows, a granular rostral, and supranasals not extending beyond the rostral (WALLACH 2005).
Another perplexing specimen (MZUF 32387) from eastern Congo has 26 midbody scale rows, a granular hourglass rostral, a small frontal not in contact with the short supranasals, and the inferior nasal suture contacting the second infralabial. The types of the above species and their synonyms (Typhlops avakubae Schmidt 1923 and Typhlops caecus pitmani Witte 1961) must be examined [...] (WALLACH 2005).
|Comment||In an unpublished PhD thesis, Wallach (1998) revived Rhinotyphlops acutirostratus for the Congo basin populations. SCHMIDT’s description (1923) of Typhlops avakubae is available online at the AMNH (search for name at the URL).|
Distribution: not in Benin fide ULLENBRUCH et al. 2010. Not listed for Togo by Segniagbeto et al. 2012. Has been erroneously listed for Benin but does not occur there (Hughes 2013). Not in Sierra Leone fide TRAPE & BALDÉ 2014: 320.
Type species: Onychocephalus caecus DUMÉRIL 1856 is the type species of the genus Letheobia COPE 1868.
Synonymy: Kaiser et al. 2013 considered the generic names Cottontyphlops Hoser 2012, Gleesontyphlops Hoser 2012, Laidlawtyphlops Hoser 2012, Smythtyphlops Hoser 2012, Trioanotyphlops Hoser 2012, Whybrowtyphlops Hoser 2012, Whybrowtyplops [sic] Hoser 2012 invalid and rejected their use instead of Letheobia.
Species of Letheobia are usually pink in life, becoming cream or yellowish in preservative. The scales are not densely pigmented and often partly transparent and therefore, the arrangement and shape of scales, especially the head shields, are notoriously difficult to assess under a dissecting microscope (Dehling et al. 2018).
|Etymology||Although not stated in the original description, the generic name is a feminine noun formed from the Greek lethe (forgotten) and bios (life), meaning forgotten life, an appropriate reference to blindsnakes. Possibly a reference to the river Lethe in Hades, associated with the Greek spirit of forgetfulness and oblivion|