Contribution to Zoology, 75 (1/2) – 2006Silvia Vejarano; Meike Thomas; Miguel Vences: Comparative tadpole morphology in three species of frogs of the genus Spinomantis (Amphibia: Mantellidae)

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Descriptions

Spinomantis aglavei (Methuen and Hewitt, 1913)

Based on ZSM 431/2004 (field number 2002.1817; DQ060232), a single specimen (DNA voucher) in stage 28 (Figs. 1A and 1B) from Kidoanafo bridge, Vohiparara, Ranomafana National park in southeastern Madagascar, collected in a small and muddy brook (21°13.50’S 47°22.21’E, 846 m above sea level) in the forest, with many pools but also rapids, diameter between 50 and 100 cm, on 21 January 2003.

For morphometric data see Tables 1 and 2. Coloration in preservative light brown darkening softly towards mid-dorsal body. Four small lines across the middle line of the dorsum. Few small darker spots on the body and intestinal wall. Intestinal spiral visible, densely and regularly rolled. Ventral part of the body lacks pigmentation. Tail (first half) with more or less the same coloration pattern as the body, except the mid lines. The end and a ventral portion of the tail and caudal fin missing because of tissue sampling. Tadpole of type IV (Orton, 1953). Body shape oval. Tail musculature strongly developed. Snout in dorsal view almost rounded. Eyes medium-sized (about 0.1 of body length) dorsally positioned. Nares rounded, positioned closer to snout tip than to center of eye, directed anterolaterally, with their openings directed laterally. Spiracle sinistral, quite anteriorly on body. Oral disc without emarginations but strongly folded mid-ventrally twice (Fig. 1C) and bordered almost entirely with papillae; 54 marginal papillae, those of the ventral part (ca. 25) twice as long and narrower at the base than the lateral ones; dorsal gap of the marginal papillae large (1.5 mm) about half of oral disc width; two submarginal papillae on each side of the upper lip and nine (short and pointed) on the lower lip, right below LTR2 . LTRF 1:2+2/1+1:1 (Dubois, 1995) or 3(2-3)/2(1) (Altig and McDiarmid, 1999); UTR1 and UTR2 subequal in length, UTR3 much shorter; LTR2 shorter than LTR1 ; UTR3 with more teeth per 0.1 millimeter (seven) than the rest of tooth rows (five). UTR2 with a small gap while UTR3 and LTR1 are separated by the jaw sheaths. Jaw sheaths distinct, with a light brown pigmentation and softly serrated edges (ca. 49 in each jaw). Sheath of upper jaw straight and sheath of lower jaw strongly curved in the middle, resembling a wide V.

FIG2

Fig. 1. Drawings of the preserved DNA voucher tadpole of Spinomantis aglavei. Series ZSM 431/2004; (A) Dorsal view. (B) Lateral view. (C) Oral disc.

Spinomantis phantasticus Glaw and Vences, 1997

Based on ZSM 421/2004 (field number 2002.1637; DQ060233), a single specimen (DNA voucher) in stage 25 (Figs. 2A and 2B Andasibe, central-eastern Madagascar, collected on 25 February 2003. Tadpoles were found in a little brook along the railway (18°55.14’S 48°26.24’E, 906 m above sea level), maximum width 1 m, with pools and rapids, and a lot of dead leaves on the bottom. For morphometric data see Tables 1 and 2. Preserved coloration light brown, with a few spots on the snout. Body dorsally with a darker longitudinal stripe and several transverse, shorter stripes. Almost no coloration on the intestinal wall; ventral part of the body lacking pigmentation; tail also with dorsal transverse stripes in the first part, and the rest of the tail with short stripes on the sides. The distal portion of the tail and caudal fin missing because of tissue sampling. Tadpole of type IV (Orton, 1953). Body shape oval. Tail musculature strongly developed. Intestine in a densely and regularly rolled spiral. Snout in dorsal view almost rounded. Eyes medium-sized (about 0.1 of body length) dorsally positioned. Nares rounded, positioned closer to snout tip than to center of eye, directed anterolaterally, with their openings directed laterally. Spiracle sinistral, quite anteriorly on body. Oral disc laterally emarginated with one medial fold in the lower part and bordered by ca. 106 marginal papillae (Fig. 2C); dorsal gap of the marginal papillae short (1.25 mm) about 0.3 of oral disc width. Marginal papillae of the anterior part of the lip are more separated and slightly shorter than the ventral ones (0.13 mm); ventral papillae which are closer to the emargination are few and small, and increase in length and number as they reach the centre (0.23 mm); seven submarginal papillae below the LTR3 . LTRF 3/1+1:2 (Dubois, 1995) or 3/3(1) (Altig and McDiarmid, 1999); all three UTR without very important length differences, UTR1 slightly shorter than UTR2 and UTR3 ; LTR2 shorter than LTR1 , LTR3 much shorter; LTR1 separated by the lower jaw sheath; LTR2 and LTR3 appear to be separated by two gaps each, but the tooth ridges are in both cases continuous, therefore possibly teeth are missing because of fixation or preservation; maybe for the same reason LTR3 has fewer teeth per millimetre (ca. 17) than the rest of teeth rows (21-28). Around 13 buccopharyngeal papillae; jaw sheaths distinct and dark with serrated edges (ca. 56 in each jaw). Both jaws almost straight, lower jaw only gently curved.

FIG2

Table 1: Morphometric measurements (all in mm) of the DNA vouchers of all species. DNA vouchers used for descriptions and drawings are marked with asterisks.

FIG2

Table 2: Number of marginal and submarginal papillae (MP, SMP) and number of teeth per labial tooth row of DNA voucher specimens examined. For rows divided by a gap, the number of teeth presented on the table is the average of the numbers on each side of the tooth row. DNA vouchers used for descriptions and drawings are marked with asterisks. LTRF: 1after Dubois (1995); 2after Altig and McDiarmid (1999).

FIG2

Fig. 2. Drawings of the preserved DNA voucher tadpole of Spinomantis phantasticus. Series ZSM421/2004. (A) Dorsal view. (B) Lateral view. (C) Oral disc

Spinomantis cf. fimbriatus

Material. ZSM 441/2004 (field number 2002.1843; DQ060234), a single specimen (DNA voucher) collected on 19 January 2003 in a small inflow to a brook locally named Mariavarata (21°15.78’S 47°25.16’E, 844 m above sea level), width 50 to 70 cm, a lot of pools with steep regions inbetween. ZSM 443/2004 (field number 2002.1848; DQ060235), series of four specimens collected on 18 January 2003 in an awashed meadow in a clearance locally named ‘Sahar’i Bernard’ (Bernard’s field) in the forest, and ZSM 445/2004 (field number 2002.1873; DQ060236), a single specimen (DNA voucher) collected in a second inflow more downstream of Mariavarata brook, very broad (1-4 m) but shallow with a stony bottom and mostly fast flowing water. This tadpole was found in the stream, in a conglomeration of dead leaves on 17 January 2003. All these localities are within the Ranomafana National Park in southeastern Madagascar. ZSM 417/2004 (field number 2002.1631; DQ060237), a single specimen (DNA voucher) from Andasibe, central-eastern Madagascar, collected in a little brook along the railway (18°55.14’S 48°26.24’E, 906 m above sea level) in 2002. For morphometric data of all DNA voucher specimens, see tables 1 and 2.

Description (based on the DNA voucher of series ZSM 441/2004). Tadpole in stage 28 (Figs. 3A and 3B). Preserved coloration light brown; few small spots between the eyes; one medial longitudinal stripe and five small transversal stripes on dorsum; intestinal wall almost lacking pigmentation and intestinal spiral visible; tail and caudal fin with many small brown spots. Ventral portion of the tail and caudal fin missing because of tissue sampling. Tadpole of type IV (Orton, 1953). Body shape oval. Tail musculature strongly developed. Tail length 32.9 mm, tail making up two thirds of total length. Intestine in a densely and regularly rolled spiral. Snout in dorsal view almost rounded. Eyes medium-sized (about 0.08 of body length) dorsally positioned. Nares rounded, positioned closer to snout tip than to center of eye, directed anterolaterally, with their openings directed laterally. Spiracle sinistral, quite anteriorly on body. Oral disc with three small ventral emarginations that create two flaps and bordered by papillae (Fig. 3C); 85 marginal papillae, small (0.1 mm) and rounded; those between the emarginations appear to be thinner than the rest. Dorsal gap of the marginal papillae short (0.94 mm) about 0.25 of oral disc width; one row of six submarginal papillae on the border of the right (in ventral view) upper part of the oral disc, 11 submarginal papillae around the UTRs and nine around the LTRs. LTRF 1:2+2/1+1:2 (Dubois, 1995) or 3(2-3)/3(1) (Altig and McDiarmid, 1999); UTR1 shorter than UTR2 , UTR3 much shorter than UTR1 and UTR2 ; LTR2 distinctly shorter than LTR1 ; UTR1 and UTR2 with less teeth per 0.1 millimetre (36 and 33 respectively) than the rest (38-53) but apparently some teeth are missing because of fixation or preservation; UTR2 separated by a gap and UTR3 separated by the upper jaw sheath. LTR3 very short. About 13 buccopharyngeal papillae. Jaw sheaths distinct and black, with softly serrated edges (ca. 72 in each jaw). Sheath of upper jaw straight and sheath of lower jaw strongly curved in the middle, resembling a wide V.

FIG2

Fig. 3. Drawings of the preserved DNA voucher tadpole of Spinomantis cf. fimbriatus. Series ZSM 441/2004. (A) Dorsal view. (B) Lateral view. (C) Oral disc.

Variation within series. The series ZSM 443/2004 contains four tadpoles, three in stage 26 and one in stage 25. The right portion of the oral disc of tadpole in stage 25 is poorly preserved and therefore the LTRF [1:2+2/1+1:1 (Dubois, 1995) or 3(2-3)/2(1) (Altig and McDiarmid, 1999), number of marginal and submarginal papillae recorded is not reliable. A further specimen has the LTR3 divided in two portions with five labial teeth on each side. The other two tadpoles have LTRF 1:2+2/1+1:2 (Dubois, 1995) or 3(2-3)/3(1) (Altig and McDiarmid, 1999). Number of marginal papillae is not highly variable 66-73. The submarginal papillae have similar number and arrangement. Coloration varies from one specimen with darker, more uniform coloration to another specimen with also uniform but much lighter coloration. All other tadpoles agree in general and oral morphology with the DNA voucher as shown in Fig. 3.

Variation among the series (Table 2). The series ZSM 445/2004 and 417/2004 contain only the DNA voucher specimen each, both in stage 25. The tadpole from series ZSM 417/2004 has a LTRF of 2+2/1+1:1 (Dubois, 1995) or 2(2)/2(1) (Altig and McDiarmid, 1999), few marginal papillae (48), and in general is smaller (BL=8.6 mm) than the DNA voucher specimens of other series (mean BL=13.44 ± 3.05 mm) and from all other examined specimens (mean BL=13.72 ± 2.09 mm). Coloration is also different, very light with almost no pigmentation at all.

The tadpole from series ZSM 445/2004 appears to have only the UTR3 divided, but the UTR2 spite the gap is not clearly visible, has two separate tooth ridges. Both tadpoles differ from the DNA voucher in not having submarginal papillae. In every other respect this and the DNA voucher of series ZSM 443/2004 agree with the specimen as shown in Fig. 3.

Remark. The DNA sequences of these tadpoles were highly divergent from Spinomantis aglavei . The one sequence from Andasibe also was distinctly divergent from the three Ranomafana sequences that were identical among each other. Most probably, these tadpoles are to be assigned to Spinomantis fimbriatus Glaw and Vences, 1994 which is known to occur in the Andasibe region (Glaw and Vences, 1994), and is so far the only Spinomantis not included in our reference data base of DNA sequences. Because so far no DNA sequence of adults of this species from either Ranomafana or Andasibe are available, and the final identification of these larvae awaits further collection of adult material.