Aglyptodactylus australis, Köhler, Jörn, Glaw, Frank, Pabijan, Maciej & Vences, Miguel, 2015

Köhler, Jörn, Glaw, Frank, Pabijan, Maciej & Vences, Miguel, 2015, Integrative taxonomic revision of mantellid frogs of the genus Aglyptodactylus (Anura: Mantellidae), Zootaxa 4006 (3), pp. 401-438 : 427-430

Aglyptodactylus australis sp. nov.

Remarks. This species has been referred to as Aglyptodactylus sp. “South” by Vences et al. (2006), Aglyptodactylus sp. aff. madagascariensis “South” by Glaw & Vences (2007) and Aglyptodactylus sp. 1 by Vieites et al. (2009). Earlier records of Aglyptodactylus madagascariensis from low-altitude sites of Andohahela by Andreone & Randriamahazo (1997) and Nussbaum et al. (1999) might refer to A. australis as well.

Holotype. ZSM 77/2004 (field number FGZC 130), adult male, from a campsite between Isaka and Eminiminy, 24°45’31’’ S, 46°51’15’’ E, 247 m above sea level, Andohahela National Park, southeastern Madagascar, collected between 29‒31 January 2004, by F. Glaw, M. Puente, M. Teschke (Thomas) & R. Randrianiaina.

Paratypes. ZSM 78/2004 ( FGZC 131), ZSM 80/2004 ( FGZC 133), both adult females, UADBA uncatalogued ( FGZC 129), adult male, same data as holotype; ZSM 62/2004 ( FGZC 104), juvenile, UADBA uncatalogued ( FGZC 103), same data as holotype, but from a slightly different, higher locality (350 m a.s.l., no coordinates taken).

Diagnosis and comparison. A species of the genus Aglyptodactylus based on (a) digital terminal expansions not completely grooved, (b) black inguinal spots, (c) second finger shorter than first finger; (d) absence of femoral glands, (e) presence of nuptial pads in males, and (f) strong phenetic similarity to other Aglyptodactylus and molecular phylogenetic relationships.

Externally, the new species is characterized by the presence of a marbled pattern on posterior surfaces of thighs, lack of a vertebral line on dorsum, a robust body, and large female body size. It differs from A. laticeps and A. securifer by more extensive webbing on feet, and a distinctly smaller inner metatarsal tubercle ( Fig. 4 ). From A. madagascariensis , the new species differs by larger female size and the lack of a fine vertebral line on dorsum (present in some specimens of A. madagascariensis ). It differs from A. chorus and A. inguinalis by larger female size, a less slender body, and the presence of a marbled pattern on posterior surfaces of thighs (lacking in A. chorus and A. inguinalis ). Furthermore, A. australis differs from all other species in the genus by substantial genetic differentiation and differences in the advertisement call ( Figs. 1 , 3 ; Tabs. 1 , 2).

Description of the holotype. Adult male ( Fig. 15 a, b), as indicated by brown nuptial pads on the first finger. Intercalary element between ultimate and penultimate phalanges presumably present given the typical bent-down pattern of toe tips. Body slender; head slightly broader than body; snout pointed in dorsal view, nostrils directed laterally, distinctly nearer to snout tip than to eye; canthus rostralis straight and distinct, loreal region distinctly concave, tympanum distinct, right tympanum round, left typanum slightly oval, its horizontal diameter 67% of eye diameter; distinct supratympanic fold; tongue removed as tissue sample; vomerine teeth distinct in two well separated, oval patches, the diameter of the group of vomerine teeth about the same diameter as choanae. Arms slender, fingers with distinct single subarticular tubercles, outer metacarpal tubercle oval, flat; inner metacarpal tubercle prominent and elliptical; fingers without webbing; comparative finger length 2<4<1<3, slightly developed terminal finger disks, without circummarginal grooves; limbs slender, tibiotarsal articulation reaches widely beyond snout tip if limb is adpressed along body; foot with an elongated inner metatarsal tubercle, no recognizable outer metatarsal tubercle, subarticular tubercle distinct, single, rounded, elongated to direction of toe tips; terminal toe disks slightly developed, lateral metatarsalia deeply separated, comparative toe length 1<2<3<5<4. Webbing formula 1(1), 2i (1.5), 2e (0), 3i (1.5), 3e (0), 4i (2), 4e (1), 5 (0). Skin on the upper surface smooth, throat and venter smooth. For morphological measurements see Table 3.

Colour of holotype in preservative (after 10 years in alcohol): head, dorsum, and dorsal surfaces of limbs reddish brown. A triangular, asymmetrical, dark brown marking between the eyes, pointed posteriorly and extended onto the eyelids. A distinct, Y-shaped marking from level of tympanum to level of sacral region. Small brownish spots and elongated markings on the whole dorsum. Inguinal region with irregular and sharply bordered black marking (a distinct one on each side). Anterior flanks with a a group of small black spots. Loreal and temporal region including tympanum brownish. A black blotch below the supratympanic fold pointing posteriorventrally. A blackish band running from the anterior margin of the eye to tip of snout narrowing at level of nostril. Upper lip whitish. Dorsal surface of hands whitish covered with minute brown spotting, dorsal surface of feet brown; thighs and shanks with brown crossbands. Posterior surfaces of thighs with a reticulated pattern of white and dark brown. Cloacal region dark brown. Three narrow crossbands on feet. Ventral surfaces of feet dark brown. Arms light brown with dark brown parallel stripes. A distinct black spot on the inner side of the lower arm. Small irregular black spots on inner side of upper arm. Posterior side of upper arm with black line. Iris blackish, pupil white. Belly and throat cream, anterior venter and ventral surface of arms cream. The lateral border between dorsal surface and ventral surface of lower arm, elbow, thigh, knee, shank, tarsus and foot dark brown.

In life, colour pattern was almost identical, differing only by a more intense reddish brown dorsal colour ( Fig. 15 a). Venter yellowish white, throat orange yellow with some pinkish marbling towards chest. Ventral surfaces of thighs pinkish brown. Palmar and plantar surfaces cream with dark brown spotting and a pinkish tint ( Fig 15 b). Upper iris golden with fine dark brown reticulation, lower iris dark brown. Iris periphery yellow.

Variation. For measurements of type specimens see Table 3. This is the largest known Aglyptodactylus species with females reaching a maximum SVL of 82.5 mm. Glaw & Vences (1992) recorded an even larger female Aglyptodactylus of 92 mm SVL from near Fort Dauphin (actually from rainforest remnants near Nahampoana north of Fort Dauphin) which can be most likely attributed to A. australis based on its enormous size. In contrast to the male holotype the head of both females is wider than long (see Table 3). Sexual dimorphism is very pronounced, the single available male measuring 57% of the female SVL. The two females are more greyish compared to the brown holotype, but the pattern of dark markings is generally very similar. Differences are obvious with respect to more extensive black spotting on flanks, inner side of arms, and dorsal surfaces of hands. Both females have dark brown spotting at outer margins of chest and posterior corners of throat. The reticulated pattern on posterior surfaces of thighs is less distinct in ZSM 80/2004 compared to ZSM 78/2004 ( Fig. 15 c, d) and the holotype. The colour and pattern of the juvenile ZSM 62/2004 (SVL 27.7 mm) is very similar to the adults, including a distinct Y-shaped marking on the back and a dark marking between the eyes.

Call. The call recorded at Andohahela on 31 January 2004 (Vences et al. 2006: CD1/Track 4) consisted of a series of 4‒5 distinctly pulsed notes repeated at regular intervals ( Fig. 16 ). Call duration varied from 1308‒1460 ms and note duration from 234‒319 ms. Inter-note intervals were significantly shorter than note duration (91‒132 ms) and pulses were emitted at a mean rate of 90.3 pulses/second within notes. Amplitude within notes constantly increased from beginning to the end of the note. Initial notes in most calls were slightly softer than subsequent notes. The dominant frequency range is 800‒3300 Hz, and a second but weak frequency band was recognizable at around 8000‒10000 Hz.

In general structure, the call of A. australis is most similar to the call considered to represent A. madagascariensis . Both calls consist of a series of pulsed notes with inter-note intervals being shorter than note duration. However, when compared in detail, notes in calls of A. australis are longer (234‒319 vs. 140‒211 ms) and the pulse rate is lower (mean 90.3 vs. 119.6/118.4 pulses/second), although calls were recorded at slightly higher temperature. These differences are well beyond the level of variation found in calls of different populations of A. madagascariensis and consequently both species are identifiable by call analyses. For comparative numerical parameters of calls see Table 2.

Natural history. Calling males and females in reproductive state were found at the edges of a shallow pond in primary rainforest, just before and during very heavy rains accompanying a cyclone. Calling males did not form large choruses, but due to the difficult weather conditions no further natural history information was recorded.

Distribution. So far known from the type locality, namely low elevations of the Andohahela National Park ( Fig. 2 ), but likely to also occur in the rainforest fragment near Nahampoana, ca. 25 km southeast of the type locality, and the adjacent Tsitongambarika forest. Furthermore, sequence data from specimens collected at Marovato, 18°41.16’ S, 48° 36.33 E, 692 m a.s.l., central eastern Madagascar (A. Crottini, pers. comm.), indicate the possible presence and wider distribution of A. australis in rainforests along Madagascar’s east coast ( Fig. 2 ). However, further sampling is necessary to confirm or refute this record (see Discussion).

Etymology. The specific epithet australis is a Latin adjective for ‘southern’ and refers to the type locality, Andohahela forest, in Madagascar’s far south.

Figures

FIGURE 1. Maximum likelihood tree based on DNA sequences (539 bp) of the mitochondrial 16 S rRNA gene showing relationships among species and populations of Aglyptodactylus. The tree is rooted with Laliostoma labrosum. Values at nodes are ML bootstrap values in percent and Bayesian posterior probabilities (shown only if> 50 % and> 0.9 respectively; support values at some of the shallow intraspecific nodes omitted for graphical reasons). Inset photos show characteristic individuals of the respective species in life. Oscillograms show representative sections (2000 ms each) of advertisement calls of the various species, respectively.

FIGURE 2. Map showing the reliably known distribution ranges of all six species of Aglyptodactylus. Note that many more records under the name A. madagascariensis are available mainly from eastern Madagascar (e. g., Blommers-Schlösser & Blanc 1991); the map shown here only includes records verified by molecular data (except Anzahamaru, the type locality of A. inguinalis, and Kirindy, the type locality of A. securifer). The Marovato record of A. australis is based on sequence data alone and in need of confirmation. The different blue colours of A. inguinalis records symbolize their substantial genetic differentiation. The map shows the remaining primary vegetation of Madagascar (www. vegmad. org), green colours indicating rainforest, reddish colours deciduous dry forest, and orange colour arid spiny forest.

FIGURE 3. Comparative oscillograms of the calls of known species of Aglyptodactylus at the same time scale (2000 milliseconds section each).

FIGURE 4. Ventral view of feet of representative specimens of Aglyptodactylus (not to scale; see Table 3 for measurements). Arrows point at the large inner metatarsal tubercles of A. laticeps and A. securifer, and at the lateral metatarsalia of A. laticeps connected by tissue rather than separated by webbing. Asterisks mark mirrored images.

FIGURE 15. Photographs in life of Aglyptodactylus australis sp. nov. from Andohahela: (a, b) dorsolateral and ventral views of male holotype (ZSM 77 / 2004); (c, d), dorsolateral and ventral views of a female paratype (ZSM 78 / 2004).

FIGURE 16. Audiospectrogram (above) and oscillogram (below) of an advertisement call of Aglyptodactylus australis, recorded at Andohahela. Air temperature 24.0 ° C.