Philautus maia, Meegaskumbura, Madhava, Manamendra-Arachchi, Kelum, Schneider, Christopher J. & Pethiyagoda, And Rohan, 2007

Meegaskumbura, Madhava, Manamendra-Arachchi, Kelum, Schneider, Christopher J. & Pethiyagoda, And Rohan, 2007, New species amongst Sri Lanka’s extinct shrub frogs (Amphibia: Rhacophoridae: Philautus), Zootaxa 1397, pp. 1-15 : 6-10

Philautus maia new species

Figs 4 , 5

Holotype

Adult female, 44.6 mm SVL, BMNH 76.3.21.18. Paratype: female, 46.1 mm SVL, BMNH 76.3.21.19. Both collected at “Poojagodde” [Poojagoda] Estate, Ramboda, Sri Lanka, by a Mr Perera ( Ferguson 1876).

Etymology

The species­epithet is derived from the Greek term for a ‘good mother’—a reference to the care the female of this species appears to have taken of its clutch of eggs. It is applied here as a substantive in apposition.

Diagnosis

Philautus maia is distinguished from all other Sri Lankan species of Philautus by the following combination of characters: (1) tympanum discernible; (2) angle of snout in dorsal aspect ~100º; (3) supratympanic fold distinct; (4) canthal edges sharp; (5) lingual papilla absent; (6) supernumerary tubercles present on fingers but absent on toes; (7) tarsal tubercle absent; (8) webbing up to or beyond second and third toes ( Fig. 6 D); (9) posterior surface of thigh with a dark­brown reticulated pattern.

Description of the holotype

(See Figs. 4 , 5 .) Mature female 44.6 mm SVL. Body elongate. Head dorsally concave; snout truncate in lateral aspect, angle of snout 102º in dorsal aspect; canthal edges sharp. Loreal region concave; interorbital space concave; internarial space flat; tympanum oval, oblique; pineal ocellus absent. Vomerine ridge present, bearing about 6 small teeth angled at about 45º relative to body axis, the ridges shorter than distance between them. Cephalic ridges, calcar, lingual papilla and co­ossified skin on skull absent. Supratympanic fold distinct. A lateral dermal fringe present on fingers; webbing on fingers rudimentary. Toes webbed (see Fig. 6 D); tarsal folds absent. Snout, interorbital space and side of head smooth; dorsum and both upper and lower flanks with glandular warts. Dorsal part of forelimb, thigh, shank and foot smooth. Throat, chest, belly and underside of thigh granular. Inner vocal slits and nuptial pad absent. Egg depressions present on belly; 15 oval eggs measuring ~4.0 x 4.8 mm, lacking jelly capsules, preserved in jar containing holotype.

Colour in preservative: Dorsum ashy brown. Interorbital area dark brown. Both upper and lower flanks pale yellow with black speckles ( Fig. 4 C). Loreal region, tympanic region and tympanum dark brown. Upper lip ashy brown. Dorsal parts of forelimb, thigh, shank and foot ashy brown with dark­brown spots; posterior surface of thigh with a dark­brown reticulation ( Fig. 5 B); underside of thigh and webbing on foot dark brown. Throat, margin of throat, chest and belly yellow with brown pigments.

Measurements of holotype ( BMNH 76.3.21.18, in mm): DBE, 16.4; DFE, 9.6; DL, 2.1; DW, 2.2, ED, 6.6; EN, 4.5; ES, 7.7; FEL, 27.0; FL I, 4.1; FL II, 5.2; FL III, 7.8; FL IV, 6.7; FOL, 35.1; HL, 18.0; HW 19.0; IML, 1.7; IN, 4.6; IO, 4.7; LAL, 9.8; MBE, 7.0; MFE, 12.1; MN, 15.7; NS, 3.0; PAL, 13.2; SVL, 44.6; TBL, 27.3; TL I, 3.4; TL II, 4.7; TL III, 7.5; TL IV, 11.2, TL V, 8.0; TYD, 2.0; TYE, 2.7; UAW, 8.6; UEW, 4.6.

Remarks

Günther (1876) assigned this species to P. reticulatus , from which it differs, however, by the absence of a lingual papilla and tarsal tubercle. Both these characters are consistently present in P. reticulatus , an extant, Endangered species restricted to the rainforest canopy in the island’s south­western lowlands up to 900 m elevation (Manamendra­Arachchi and Pethiyagoda 2005). The same two characters also serve to distinguish P. maia from P. lunatus , P. papillosus and P. reticulatus , to which the diagnoses and key of Manamendra­Arachchi and Pethiyagoda (2005) refer it.

Günther (1876) observed of the holtype of P. maia , “In a small collection of Ceylonese frogs submitted to my examination by Mr. W. Ferguson, F.L.S., there was a frog which I consider to be Polypedates reticulatus , and which had the ova attached to the abdomen when that gentleman obtained it. The ova are now detached, but still firmly adhere to one another, forming a flat disk.” Remarkably, despite the passage of time, the depressions formed on the belly of this specimen are still clearly visible ( Fig. 4 B).

We have not observed such a brooding behaviour in any of the 17 Sri Lankan Philautus for which reproduction has thus far been investigated ( Bahir et al. 2005). Of these 17, all but one deposit their eggs in nests excavated in the forest floor. A single species in Sri Lanka (P. f e m o r a l i s) and two in India are known, however, to attach their clutch to leaves, in the form of a flat disc, where they are then abandoned to hatch ( Bossuyt et al. 2001; Biju 2003). We feel it unlikely that the gait of a frog would permit a clutch of eggs to be carried adhered to its abdomen over the incubation period of several weeks typical of Sri Lankan Philautus . Further, the disc­shaped clutch and the absence of soil particles on the egg mass suggest that this frog was an arboreal, leaf­nesting species similar to P. femoralis . An examination of the eggs that were originally attached to the specimen also suggests that eggs had been freshly deposited, or perhaps were unfertilized, due the distinct absence of well formed embryos within, further reinforcing the notion that this species did not provide brood care. Although we do not entirely discount the possibility that P. m a i a carried its clutch on its belly (a behaviour unknown in Anura : Thibaudeau and Altig 1999) or remained positioned on it, we think it more likely that it was an arboreal nester captured while still positioning its clutch, or an individual that died while doing so. The collector may have assumed that the eggs, in addition to being adhered to one another to form a disc, were also attached to the female’s abdomen. We observed this to be the case in P. f e m o r a l i s in some instances, when the leaves on which eggs were deposited were not sufficiently damp. There is also no sign that the skin of the abdomen of P. m a i a was in any way adapted to carry adhesive eggs: as is also in the case with P. femoralis , the skin on its venter is granular.

The key of Manamendra­Arachchi and Pethiyagoda (2005) and the diagnoses of Meegaskumbura and Manamendra­Arachchi (2005) show P. m a i a to be closest morphologically to P. lunatus and P. papillosus . Principal components analysis (unadjusted for body size, see Fig. 6A ) shows that P. m a i a separates from these species on both PC axes. However, both sexes of P. m a i a separate from P. reticulatus (to which Günther 1876, referred its type specimens) only on a single PC axis. The PC(1) axis explains 88 % of the variance with all variables showing high, positive loadings (component loadings range from 0.799 to 0.980), suggesting that the variation relates mostly to size. The PC(2) axis explains only 4 % of the total variance and represents mostly the variation in eye diameter, eye­to­snout distance, and femur length. Eye diameter loads positively, while femur length and eye­to­snout distance load negatively. Philautus maia also separates from females of P. lunatus , P. papillosus and P. reticulatus on the PC(1) axis, with P. lunatus being the smallest species and P. reticulatus being the largest. The new species completely overlaps females of P. reticulatus on PC(2) axis.

The size­adjusted discriminant function analysis serves to distinguish P. m a i a from P. lunatus , P. papillosus and P. reticulatus ( Fig. 6 B). The analysis correctly classified 100 % of each of the four species (Wilks’ lambda 0.016, p = 0.7). The first canonical variable best discriminates between the species and accounts for 57 % of total dispersion (eigenvalue 6.24). The second variable accounts for 35 % of dispersion (eigenvalue 4.05). In the canonical variables plot, the centroids are (­0.238, ­6.447) for P. maia , (6.874, 0.243) for P. lunatus , (­4.577, 0.485) for P. papillosus and (­0.172, 0.477) for P. reticulatus . The first variable represents mostly distance between front of eyes (standardized canonical discriminant function, SCDF ­6.410), distance between back of eyes ( SCDF 5.224), foot length ( SCDF ­3.870), eye­to­snout distance ( SCDF 2. 990), eye diameter ( SCDF ­2.520), and third finger length ( SCDF 2.112).The second canonical variable represents mostly foot length ( SCDF ­2.751), eye to snout distance ( SCDF 2.257), distance between front of eyes ( SCDF ­1.691), third finger length ( SCDF 1.593), and internarial distance ( SCDF ­1.335).

Conservation status

Ferguson (1876) stated that the type specimen was sent to him by “Mr Perera, then conductor on the Poojagodde estate in the Ramboda District, and from a high elevation.” Poojagoda is in fact a division of Frotoft Estate, Ramboda (7°04’30”N, 80°42’15”E), a tea plantation ~ 1400 m above sea level. The Pedro Forest Reserve, which extends along a forested ridge bordering Frotoft Estate about 1 km north of Poojagoda, is now the only remaining undisturbed habitat in this area. However, surveys of this forest failed to detect this species. Clearance of the cloud forest adjacent to Frotoft Estate in 1978 also resulted in the extinction of Albizia lankaensis (Mimosaceae) , a tree species formerly endemic to this site ( Kostermans 1980). Given that Philautus maia has not been recorded since 1876 despite surveys that have included forests in the vicinity of the type locality in the period 1993–2003 (see Manamendra­Arachchi and Pethiyagoda 2005), and given the disappearance of its habitat, we consider this species Extinct in terms of the IUCN’s Red List criteria.

Figures

FIGURE 4. Holotype female of Philautus maia, 44.6 mm SVL, BMNH 76.3. 21.18. A. Illustration of eggs carried on venter in Günther (1876). B. Ventral view, showing depressions made by eggs. C. Lateral view, showing speckled pattern.

FIGURE 5. Holotype female of Philautus maia, 44.6 mm SVL, BMNH 76.3. 21.18. A. Lateral aspect of head. B. Thigh, showing reticulated pattern. C. Left hand. D. Left foot. E. Diagrammatic representation of left­foot webbing. Scale bars = 1 mm.

FIGURE 6. A. Factor scores (no rotation) of principal components analysis of mensural data of P. m a i a (square), P. reticulatus (circle), P. lunatus (rhombus) and P. papillosus (star) (females represented by open symbols, males by solid symbols). B. Canonical variables plot of discriminant function analysis of size­adjusted residuals (the 95 % confidence ellipse is centered on the centroid).