Litoria dentata ( Keferstein 1868 )

Rowley, J. J. L., Mahony, M. J., Hines, H. B., Myers, S., Price, L. C., Shea, G. M. & Donnellan, S. C., 2021, Two new frog species from the Litoria rubella species group from eastern Australia, Zootaxa 5071 (1), pp. 1-41 : 23-27

Litoria dentata ( Keferstein 1868)

Robust Bleating Tree Frog

Hyla dentata Keferstein W. 1868 . Über die Batrachier Australiens. Archiv für Naturgeschichte Berlin 34, 253–290 [284].

Figs 9 , 10

Holotype. ZFMK 28808 (ex Zoologischen Museums Greifswald ( ZMG) specimen ZMG 123 a), from New South Wales ( NSW), Australia.

The type does not have any nuptial pads, which are visible in both breeding and non-breeding adult male Litoria dentata , and therefore is likely to be a female. According to Harold Cogger (pers. comm.) the SVL of the holotype (41 mm) differs from that given in the original description (Körper = body 29 mm; Keferstein 1868) suggesting that the length stated in the original description was erroneous.

Material examined. See Supplementary Table S1 for details of all material examined.

Revised diagnosis. Litoria dentata is distinguished from all species in the Litoria rubella group by a combination of (1) adult body size 28–42 mm in males and 29–42 mm in females, (2) relatively robust build, (3) the presence of a single, continuous, irregularly edged, dark brown dorsal band, (4) the absence of light spots on the dorsum, (5) lack of a well-defined pale mid-dorsal stripe, (6) absence of distinctive pale markings above the groin, vent and along lower leg, (7) a dorsolateral line diffusing above insertion of the arm, and (8) adult males having a vocal sac that is black or very dark yellowish black when deflated and yellowish brown when inflated.

Redescription of holotype. We redescribe the holotype from high quality images of the preserved specimen. SVL 41 mm (Cogger pers. comm.). Habitus relatively robust; head widest at eyes, slightly longer than wide; snout rounded in lateral view and bluntly rounded in dorsal view ( Fig. 9 ); nostrils prominent in dorsal profile; tympanum circular and clearly visible. Legs short; fingers and toes with prominent terminal discs, fingers with basal webbing, toes half webbed; sub-articular tubercles prominent; nuptial pads absent; inner metatarsal tubercle prominent, approximately one third of the length of first toe. Pectoral fold present. Venter coarsely granular, especially posteriorly; dorsum smooth. Colour in life not described in original description by Keferstein (1868). Colour after more than 150 years of preservation medium brown dorsally, creamy yellowish brown ventrally, finely stippled dark brown laterally, with paler patches on dorsum and a pale dorsolateral stripe ( Fig. 9 ).

Variation. Male SVL 28–42 mm, females SVL 29–42 mm. Summary of variation in morphometric variables for each sex is presented in Table 5 .

Variation in colour is described from images taken in life ( Fig. 10 ). Dorsal colouration varies from cream (e.g. Fig. 10E ) to warm medium brown (e.g. Fig. 10A, B ). All individuals have a distinct darker brown patch across head and down the back, narrowing in width over the axilla and then mid-dorsum, more diffuse posteriorly. A narrow, diffuse, medium-brown mid-dorsal line obvious in some individuals (e.g. Fig. 10A ) and absent in others. Distinctly darker brown dorsolateral line running from eye, over tympanum, and diffusing above insertion of arm, becoming indistinct (versus continuing to groin as distinct line) in all individuals. Dark-brown stripe between eye and snout distinct in some individuals. Bright white patch on upper lip between lower margin of eye and insertion of the arm present in all individuals. Dorsal surface of limbs brown, finger tips often paler brown; toe tips pale brown, cream or pale yellow (e.g. Fig. 10F ). Yellowish wash and/or paler cream patches in the groin region in some individuals, but both absent in most individuals examined. Back of thighs transparent pinkish orange with opaque, creamy yellow flecks; belly white; vocal sac in males black or very dark yellowish black when deflated and yellowish brown when inflated ( Fig. 10 ). Iris copper-brown.

Advertisement call. Call descriptions are based on the calls of nine individuals ( Table 6 , Figs. 6 , 8 ). The advertisement call of L. dentata comprises a single, highly-pulsed note. Individuals had a mean call duration of 0.84– 1.33 s and an average of 44–53 uniformly spaced pulses repeated at a mean rate of 37–57 pulses/s. Calls were amplitude modulated, increasing rapidly to a peak at approximately 10% of the call duration. The mean dominant frequency was 2.9–4.0 kHz.

Comparison with other species. The distribution of L. dentata potentially overlaps with that of L. rubella in the north and abuts that of L. balatus sp. nov. in the north and L. quiritatus sp. nov. in the south. It is allopatric with the other five members of the L. rubella species group ( L. electrica in north-western Queensland, L. congenita and L. pygmaea in New Guinea and L. capitula on Tanimbar Islands, Indonesia). Litoria dentata can be morphologically distinguished from L. rubella by the presence of continuous, irregularly edged, dark brown dorsal band and less robust body (versus head much narrower than body in L. rubella ). It can be distinguished from L. electrica by the presence of continuous, irregularly edged, dark brown dorsal band (versus two dark chocolate-coloured bars across the dorsum). It can be distinguished from the New Guinean species L. congenita and L. pygmaea by absence of light spots on dark dorsal background (versus large and conspicuous usually present in L. pygmaea ; smaller and more variable usually present in L. congenita ). It can be distinguished from L. capitula by the absence of distinctive pale markings above the groin, vent and along lower leg that are present in L. capitula .

Litoria dentata can be distinguished from L. quiritatus sp. nov. by males having a vocal sac that is black or very dark yellowish black when deflated and yellowish brown when inflated (versus yellow when deflated and inflated). It can be distinguished from L. balatus sp. nov. by males having a vocal sac that is black or very dark yellowish black when deflated and yellowish brown when inflated (versus black when deflated and inflated), having a dorsolateral line diffusing above insertion of arm (versus continuing to groin) and having a less slender habitus ( Fig. 5 ). From a genetic perspective, apomorphic nucleotide states at 28 sites in the mitochondrial ND4 gene reliably diagnose L. dentata from L. balatus sp. nov. and L. quiritatus sp. nov. ( Table 7 ).

Distribution. Found along the coast of northeastern NSW from Taree (location 9) and Upper Pappinbarra (location 12) to at least as far north as the NSW-Queensland border (Border Ranges National Park, Fig. 7 ). Determination of the species identity of populations along the border (e.g. Springbrook, Numinbah Valley, Girraween National Park, Durikai State Forest) will require collection of nuclear gene data. It is possible that L. dentata extends further north along the Great Dividing Range as there are records of this species complex from upland mesic forests at Main Range, e.g. Cunningham’s Gap and Goomburra (HBH unpublished data). Litoria dentata has also been introduced into Lord Howe Island ( Plenderleith et al. 2015; Fig 2 .). The known elevation range of the species is from sea level to ~ 1250 m.

Ecology. Litoria dentata calls from the ground or emergent vegetation associated with permanent or ephemeral water courses and ponds in both natural and disturbed habitats. Published descriptions of oviposition, egg and larval morphology, development and behaviour for L. dentata sensu lato (Anstis 2008) are based on L. quiritatus sp. nov. and have not been documented for L. dentata . The species is relatively commonly recorded via FrogID (>1600 records from 10 November 2017 – 30 June 2021), and is relatively commonly heard calling in disturbed areas, with 17% of FrogID records of the species documented as being in suburban or urban habitats and 43% of records in rural areas. Litoria dentata has been detected calling from August to March, with single recordings in April and June, and a peak calling period of October to April via the FrogID project.

Conservation status. Litoria dentata is a relatively widespread frog species, with an estimated Extent of Occurrence of approximately 94,000 km 2. There are no documented or suspected population declines, so the species is likely to meet the IUCN Red List criteria ( IUCN 2012) for Least Concern.

Figures

FIGURE 2. Litoria dentata sensu lato mtDNA Bayesian inference tree with Bayesian posterior probabilities (left) and ML bootstrap proportions (right) at nodes. The tree was rooted with members of the Litoria peronii species group (Table 1), which were not included here to facilitate legibility of terminal taxon names.

FIGURE 5. Body shape in sexually mature males. Litoria balatus sp. nov. A–C) QM J92768, Ormeau Hills, Qld, J92497, Moggill, Qld and J92771, Woongoolba Conservation Park, Qld; L. dentata D–F) AMS R184705 and R184704, Oxley Wild Rivers National Park, NSW; AMS R184779, Kyogle, NSW, and L. quiritatus sp. nov. G–I) AMS R183115 and R183112, Ourimbah Creek Road, NSW; AMS R147054, Homebush Bay, NSW. Images were scaled to the same snout-vent length to facilitate comparisons.

FIGURE 6. Call variation in Litoria balatus sp. nov., L. dentata and L. quiritatus sp. nov. Advertisement calls displayed as a 2 s waveform of relative amplitude (Rel. amp.) over time and corresponding spectrogram of frequency (Freq.) over time. The recorder of each call is listed in Table 6. Litoria balatus sp. nov.—A) holotype QM J91105, Anstead Bushland Reserve, Anstead, Qld (21°C), B) Karawatha Forest, Brisbane, Qld (24.5°C), C) FrogID capture 12633, Witta, Qld; L. dentata—D) AMS R184704, Oxley Wild Rivers National Park, NSW (18.5°C), E) AMS R184779, Kyogle, NSW (20.8°C), F) FrogID capture 6860, Cawongla, NSW; L. quiritatus sp. nov.—G) holotype AMS R185759, Coalcliff, NSW, H) not vouchered, Ourimbah NSW (22.8°C), I) FrogID capture 10260, Surf Beach, NSW.

FIGURE 7. Map showing sampling detail in south-eastern Queensland and north-eastern NSW. Symbols show mtDNA clade (black squares—L. balatus sp. nov., red triangles—L. dentata), letters show the morphological group (b—L. balatus sp. nov.). Hollow red triangle symbols indicate locations [33, 34, 36, 38] with evidence of mitochondrial introgression. Numbers indicate locations where specimens analysed for molecular genetics were collected (Table 1). Small symbols are ALA voucher records assigned to each species.

FIGURE 8. Variation in advertisement calls traits in Litoria balatus sp. nov., L. dentata and L. quiritatus sp. nov. A) Boxplots of i) Average pulses per call, ii) average dominant frequency (kHz), iii) average call duration (s) and iv) average pulse repetition rate (pulses/s) in, and B) i) Average pulses per call and ii) average pulse repetition rate (pulses/s) with ambient temperature.

FIGURE 9. Holotype of Hyla dentata A) dorsal, B) ventral, C) lateral view of head, D) palmar view of hand, and E) plantar view of foot.

FIGURE 10. Images in life of Litoria dentata. A) male AMS R184779, Kyogle NSW (Jodi Rowley), B) male AMS R184704, Oxley Wild Rivers National Park, NSW (Jodi Rowley), C) male, no voucher, Guy Fawkes River National Park, NSW (Jodi Rowley), D) amplexing pair, no vouchers, Guy Fawkes River National Park, NSW (Jodi Rowley), E) male, no voucher, Guy Fawkes River National Park, NSW (Jodi Rowley), F) male, no voucher, Barrington NSW (Jodi Rowley), G) male, no voucher, Kookabookra NSW (Jodi Rowley), H) male AMS R184779, Kyogle, NSW (Jodi Rowley), I) male AMS R184704, Oxley Wild Rivers National Park, NSW (Jodi Rowley), J) male AMS R184705, Oxley Wild Rivers National Park, NSW (Jodi Rowley).