Rhinatrema bivittatum (Guérin-Méneville, 1838), Guerin-Meneville, 1838

Maciel, Adriano O. & Hoogmoed, Marinus S., 2011, Taxonomy and distribution of caecilian amphibians (Gymnophiona) of Brazilian Amazonia, with a key to their identification, Zootaxa 2984, pp. 1-53 : 42-44

Rhinatrema bivittatum (Guérin-Méneville, 1838)

Caecilia bivittatum Guérin-Méneville,1838:16 .

Rhinatrema bivittatum: Duméril & Bibron, 1841: 288 ; Taylor, 1968: 159; Hoogmoed, 1979: 273; Frost, 1985: 637; Lescure & Marty, 2000: 294; Gaucher et al., 2004; Frost, 2008; Stuart et al., 2008: 95.

Diagnosis. Maximum known TL 246 mm. Rhinatrema with a large yellow cephalic spot; total body annuli 315– 384. Males may have granules on ventral surface of tail, posterior of vent. Ventrally complete annular grooves posterior of vent only in females. Longitudinal grooves may be present on the tongue or not. First and second nuchal grooves distinct, third nuchal groove not readily distinct from annular and collar grooves.

Description. TL 22.2–31.4 times (26.6 ± 2.6; n = 10) BW. Nostrils subcircular, visible from above, near tip of snout. Eyes visible in open orbit; positioned midway between nostrils and corner of mouth, slightly closer to nostrils than corner of mouth in most specimens. Eyes at same level as or slightly above nostrils. First nuchal groove distinct dorsally; second complete dorsally and ventrally; third groove indistinct; no dorsal transverse groove on first collar. Body subcylindrical, slightly wider than deep. Most annular grooves complete, except some anterior grooves which are ventrally incomplete (e.g. six in MPEG 23548), and grooves interrupted by vent (e.g. five in MPEG 23549). Small terminal shield. Tail small and slender. Sexual dimorphism in structure of tail: all tail annular grooves are incomplete in males, due to presence of tubercles on ventral surface of tail; females without ventral tubercles but with complete and some (e.g. four in MPEG 23548) incomplete annuli. Dermal scales from first body annulus to last annulus on tail; one row of dermal scales per body fold, rows completely encircling body, except in first incomplete body annulus and in incomplete tail annuli. Vent transverse or T-shaped ( Fig. 22 ); AD 10–12 (11 ± 5; n = 7). Paired anal papillae present or not; found in one of five males and absent in five analyzed females. According to Taylor (1968), tongue strongly marked by grooves but in specimens studied here longitudinal grooves are absent or only slightly distinct on surface of tongue. PMT maximally 28 with variation in size, maxillary teeth slightly larger, they may extend posteriorly of level of choanae as PPT. PPT maximally 28, with hardly any variation in size; smaller than maxillary teeth. DT maximally 25, approximately same size as PMT. ST at most 28, approximately same size as PPT.

Color. Tip of snout yellow; irregular, large yellow spot on anterior region of head, generally not reaching tip of snout, posteriorly surpassing level of eyes, but not reaching occipital region. Irregular yellow stripe connecting eyes and nostrils. Upper and lower border of mouth same yellow as cephalic spot, and those two stripes may fuse into one stripe on side of head behind corner of mouth. Gular region same color as venter; yellow stripe with irregular upper and lower border on sides of body from level of collars to level of vent; can be fused to mouth stripes. Dorsum of body brown with small yellow spots randomly distributed; underside slightly paler than dorsum and with more dispersed yellow spots. A yellow spot may be present on dorsal part of tail (e.g. MPEG26941 and IEPA/ TQ287) or be absent (e.g. MPEG 23549, IEPA/TQ306, IEPA/TQ348, IEPA/TQ272). Females with small paler region close to tip of tail. Tongue dark.

Variation. Males may have a group of tubercles on ventral region of tail ( Fig. 22 ); absent in females. No apparent sexual difference in number of annuli as suggested by Nussbaum & Hoogmoed (1979). Further data on variation in description and in Table 14 .

Rhinatrema ron Rhinatrema bivittatum

Rhinatrema ron Rhinatrema bivittatum

Male Female Male Female Distribution. Guyana, French Guiana, Suriname and Brazil (states of Amapá and Pará north of the Amazon) ( Fig. 23 ).

Remarks. Nussbaum & Hoogmoed (1979) examined only four specimens of R. bivittatum : the holotype from Cayenne, French Guiana, and three specimens collected in Brazil, Guyana and Suriname. Recent collections in French Guiana ( Lescure & Marty, 2000; Wilkinson & Nussbaum, 2006) and in Brazil show that this species is not uncommon.

Taylor (1968) noted that the second collar is distinct and larger than first, but did not mention the third nuchal groove. He considered the first few ventrally incomplete body annuli as the posterior limit of the second collar in both R. bivittatum and Epicrionops spp. ( Taylor 1968). Here we regard the third nuchal groove as indistinct and consequently also the posterior delimitation of the second collar. Gower et al. (2010) and Wilkinson & Gower (2010) identified the third nuchal groove in Rhinattrema as the anteriormost groove behind the second nuchal groove that wraps around beyond the stripe and on to the ventral surface.

Gower et al. (2010) presented data on variation in mostly French Guiana specimens of R. bivittatum . They noted that all specimens they examined had a yellow spot on the dorsal surface of the body terminus. Gower et al. (2010) and Wilkinson & Gower (2010) mentioned that the only Rhinatrema specimen (RMNH 17667) known from Suriname possibly represents a species different from R. bivittatum , R. shiv and R. ron by having a longer tail and a higher number of tail annuli.

Figures

FIGURE 22. Views of vent region of Rhinatrema. From left to right: female of R. bivittatum IEPA TQ 347; male of R. bivittatum IEPA / TQ 287; female of R. ron MPEG 20177.

FIGURE 23. Distribution of the genus Rhinatrema. Square represents R. shiv. Circles represent R. bivittatum and triangles R. ron. 1. Kaieteur National Park, Guyana (Kok & Kalamandeen, 2008; Gower et al., 2010); 2. Winiperu, Guyana (Nussbaum & Hoogmoed, 1979); 3. Brownsberg Natural Reserve, Suriname (Nussbaum & Hoogmoed, 1979); 4 - 10. Localities in French Guiana plotted as an adaptation of map of Lescure & Marty (2000: 295); 11. Parna Montanhas do Tumucumaque, Laranjal do Jari, Amapá, Brazil; 12. Serra do Acaraí, Oriximiná, Pará, Brazil; 13. Floresta Nacional Amapá, Ferreira Gomes, Amapá, Brazil; 14. Reserva de Desenvolvimento Sustentável do rio Iratapuru, Laranjal do Jari, Amapá, Brazil; 15. Almeirim, Pará, Brazil; 16. Laranjal do Jari, BR 156, Amapá, Brazil; 17. Porto Trombetas, Oriximiná, Pará, Brazil; 18. Urucará, Amazonas, Brazil; 19. Reserva INPA-WWF, km 76 BR 174. Amazonas Brazil.

Tables

TABLE 14. Morphometric (in mm) and meristic data (range, mean ± standard deviation and sample size in parenthesis) of Rhinatrema spp. from Brazilian Guiana.

	Male	Female	Male	Female
TL	97–193 171.6±18.6 (23)	167–263 209.8±26.8 (10)	145–188 166.2±16.8 (5)	138–246 199.4±35.2 (5)
HW	3.7–6.1 5.3±0.4 (23)	5.5–7.2 6.2±0.5 (10)	4.7–5.5 5.1±0.3 (5)	4.4–6.4 5.6±0.7 (5)
HL	5–9.2 7.8±0.8 (23)	8–10 9±0.6 (10)	7.5–8.9 8.3±0.6 (5)	7.5–9.4 8.6±0.6 (5)
HH	2.4–4 3.5±0.3 (23)	3.3–5.3 4.2±0.6 (10)	2.9–3.6 3.4±0.3 (5)	2.9–3.9 3.6±0.3 (5)
BW	4.7–7.9 6.9±0.6 (23)	7.1–12.2 8.8±1.5 (10)	5.5–7.4 6.2±0.8 (5)	6.2–8.7 7.6±1 (5)
BH	3.9–7.4 6.1±0.7 (23)	6–12.3 8.2±2 (10)	3.6–5.9 4.9±0.8 (5)	4.4 –7.5 6.4±1.2 (5)
WNC	3.8– 6.6 5.5±0.6 (23)	5.3–8.1 6.7±0.8 (10)	4.5–5.7 5.1±0.4 (5)	4.4 –7 5.8±0.8 (5)
WTR	4–5.9 5.2±0.4 (23)	5.4–9.5 7±1.3 (10)	3.6–4.3 3.9±0.3 (5)	4.2–6.3 4.9±2.1 (5)
WV	2.8–4 3.5±0.7 (22)	3.8–6.3 4.7±0.8 (10)	2.3–3.1 2.7±0.3 (5)	2.4–3.5 3±1.3 (5)
EE	2.2–3.6 3.3±0.3 (23)	3.1–4 3.5±0.3 (10)	3.5–4.2 3.9±0.2 (5)	2.9–4.1 3.7±0.4 (5)
EN	1.9–2.8 2.5±0.2 (23)	2.3–3.4 2.8±0.3 (10)	2.4 –2.9 2.6±0.2 (5)	2.2–2.8 2.6±0.2 (5)
EJA	1.6–3 2.6±0.6 (22)	3–4 3.3±0.3 (10)	2.1–3.1 2.6±0.4 (5)	2.3–3.3 2.9±0.3 (5)
EMM	0.5–0.9 0.7±0.08 (23)	0.7–1.1 0.9±0.1 (10)	0.6–0.8 0.7±0.07 (5)	0.4–0.9 0.6±0.2 (5)
TN	1.9–2.7 2.4±0.5 (22)	2.3–3.3 2.7±0.2 (10)	2.5–2.9 2.7±0.2 (5)	2.4–2.9 2.7±0.2 (5)
NN	0.9–1.6 1.4±0.2 (23)	1.3–1.8 1.5±0.1 (10)	1.3–1.6 1.4±0.1 (5)	1–1.6 1.4±0.2 (5)
NMM	0.3–0.6 0.5±0.08 (23)	0.5–0.8 0.6±0.06 (10)	0.5–0.6 0.5±0.04 (5)	0.4–0.7 0.5±0.1 (5)
NTS	0.4–0.9 0.7±0.1 (23)	0.7–1 0.8±0.1 (10)	0.6–0.8 0.7±0.08 (5)	0.5–0.8 0.7±0.1 (5)
TAW	2.3–3.2 2.7±0.6 (22)	3–4.3 3.4±1.4 (8)	1.9–2.5 2.2±0.2 (5)	1.3–2.8 2.3±1 (5)
TAL	1.4–3.5 2.1±0.4 (23)	1.9–2.6 2.3±0.7 (9)	1.5–2 1.7±0.2 (5)	1.8–2.9 2.4±0.4 (5)
TAA	3–8 4.2±1.3 (22)	3–5 4±0.4 (10)	3–5 4.2±0.7 (5)	3–7 5.4±1.3 (5)
TBA	276–338 298±62 (22)	285–313 295.4±10.2 (10)	329–358 341.2±10.7 (5)	333–360 345.6±9.9 (5)
AD	13–17 14.6±5 (20)	15–20 17±5.5 (9)	10–11 10.3±5.1 (3)	11–12 11.2±4.5 (5) continued next page