Limnodynastes superciliaris ( Keferstein, 1867 )

Parkin, Tom, Rowley, Jodi J. L., Gillard, Grace L., Sopniewski, Jarrod, Shea, Glenn M. & Donnellan, Stephen C., 2024, Systematics and Taxonomy of the Northern Banjo Frog (Anura: Limnodynastidae: Limnodynastes terraereginae) and Allied Taxa, Ichthyology & Herpetology 112 (1), pp. 76-105 : 93-95

Limnodynastes superciliaris ( Keferstein, 1867)

Figures 14 , 15

Suggested common name: Coastal Banjo Frog

Holotype.— ZFMK28331 (adult male), type locality originally stated as Australien (¼ Australia). Most likely collected from the environs of Sydney between 1857–1862 by German natural history collector Bernhard Rudolf Sch utte € (see Appendix 1).

Material examined.— See Supplementary Table S1 (see Data Accessibility) for full list of specimens used in morphometric analyses.

Holotype measurements (mm).— SVL 44.9; FOL 27.8; TIB 16.9; THL 16.8; HW 19.7; IOD 4.4; DFE 6.9; IND 4.1; NS 4.3; EN 3.3; ED 5.4; HDD 8.3; SL 7.6; HL 15.9; UAL 7.6; LAL 8.4; HAL 10.3; AL 26.3; FL 20.5; IMT 3.4; TEY 1.4; Fin3W 0.9; Toe4W 1.2.

Revised diagnosis.— Limnodynastes superciliaris can be diagnosed from all other species in the L. dorsalis group by the combination of: (1) relatively small adult body size ( SVL for males 34–60 mm; females 42–63 mm), (2) moderately robust build, (3) vestigial webbing trace on the hind foot (i.e., webbing does not extend beyond, or only slightly extends beyond, the first subarticular tubercle on the first toe [ Fig. 10C ]), (4) pale and immaculate, almost translucent, ventral surface ( Fig. 11C ), (5) lacks scarlet suffusions in the groin, (6) advertisement call of a high dominant frequency (0.5–1.5 kHz, mean 1.2 kHz) and short duration (0.04– 0.12 s, mean 0.07 s), and (7) genetically by 17 apomorphic character states on the ND4 gene (Table 4) .

Redescription of holotype.— Described from high-resolution images of the preserved specimen after more than 158 years in preservative. Habitus moderately stout and robust. Dorsum and ventral surface smooth. Head large, broadest at tympanum and wider than long. Head appears rounded from above and largely flat in profile, sloping abruptly at the snout. Nostrils are slightly raised and outward-facing. Eyes large and concealed, tympanum indistinct. Arms and legs short and moderately slender, tibial gland prominent, oval-shaped and approximately 60% length of tibia. Four fingers and five toes, all rounded, slender and tapering without terminal discs. Webbing on fingers absent and reduced to a vestigial trace on toes ( Fig. 10 ), no trace of a distended spatula on 2 nd finger, indicating specimen is male. Subarticular tubercles prominent on fingers and toes, metacarpal tubercles prominent, inner-metatarsal tubercle also prominent, wedge-shaped and slightly longer than the first toe. Soles of feet smoothly textured. Many small, raised tubercles of varying sizes scattered on posterior edge of thighs and cloaca.

Color in preservative.— Dorsal surface medium brown with a mosaic of lighter and darker brown, cream or yellow paravertebral lines, blotches, and spots. Distinct light cream-yellow vertebral stripe. Pattern transitions to a complex light cream-yellow and dark brown stippling on lateral surface and then completely pale cream, almost translucent on the ventral surface. Prominent cream subaural gland running from below eye to shoulder, with broad dark brown band running through eye. Upper surface of arms and legs consists of complex pattern of light and dark brown, cream-yellow blotches and spots, tending darkest inside the thigh. Posterior edge of forearm with cream stripe. Lower surface of arms and legs pale cream, almost translucent. Raised tubercles around cloaca and posterior edge of thighs, cream-yellow. Slightly darkened throat pigment indicating the specimen is male.

Variation.— Summary of variation in morphometric characters for each sex is presented in Table 6 and Figure 5 .

Color and pattern variation (in life).— Variation in color is described from images of genotyped specimens taken in life. Ventral surface plain, unpatterned cream anteriorly to translucent pearl posteriorly. Vocal sac often darker yellowbrown and mottled in males. Distinct scarlet patches absent from inguinal region and legs. Dorsal surface dark to light brown with rose-gold or crimson tinge, often with longitudinally aligned paravertebral stripes blotches or mottling. Red-light brown vertebral stripe present and distinct, broken, faded, or absent. Lateral zone light brown fading to cream-white ventrally with transition often marked by a zone of gray, black, and yellow, or cream spots and mottling. Posterior thigh flash black with gray, cream, yellow or orange mottling or blotching. Soles of feet light to dark brown with gray or cream speckling. Lateral edge of foot with yellow to brown cream stripe. Shoulders with yellow, cream, brown, or gold patch, forearm darker gray or brown and usually mottled. Light brown, cream, or gold subaural gland with dark gray to black stripe above extending from rostrum through eye to edge of subaural gland.

Advertisement call.— The advertisement call description of L. superciliaris is based on the calls of 19 individuals from the Sydney Basin bioregion. The advertisement call consists of a single, resonant note. Individuals had a mean dominant frequency of 0.5–1.5 kHz, and a mean fundamental frequency of 0.5–0.8 kHz. On average, advertisement calls had a duration of 0.04– 0.12 s ( Table 7; Fig. 8 ).

Distribution.— Most restricted distribution of the three species (approximately 26,000 km 2). Its range is centered entirely within the Sydney Basin and North Coast bioregions, including the Wollemi, Cumberland, Pittwater, Sydney-Cataract, Wyong, Hunter, Karuah-Manning, and Macleay-Hasting sub-bioregions. Mostly occurs in low-lying areas; however, has been recorded up to 600 m a.s.l. in the Blue Mountains National Park. Southerly distribution limits for this species include Stanwell Tops/Dharawal National Park. Also found throughout the Hawkesbury and Cumberland Plains region, extending to the central, mid-northern, and northern NSW coastline to at least South West Rocks and historically the Nambucca River. Does not occur on the southern coast of NSW as reported previously (i.e., Parker, 1940; Martin, 1972; Anstis, 2017). Specimens from Jervis Bay have been confirmed by our genetic analyses to represent L. dumerilii insularis .

Habitat.— Associated with sandy heathlands, coastal acid swamplands (wallum), and dry open sclerophyll forest. Appears to prefer remnant habitats, uncommonly recorded in urban or agricultural areas. Occurs within a variety of threatened vegetation communities, including the Castlereagh Scribbly Gum and Agnes Banks Woodlands of the Sydney Basin Bioregion (Endangered); Temperate Highland Peat Swamps on Sandstone (Endangered); River-flat eucalypt forest on coastal floodplains of southern New South Wales and eastern Victoria (Critically Endangered); Eastern Suburbs Banksia Scrub of the Sydney Region (Endangered); Coastal Upland Swamps in the Sydney Basin Bioregion (Endangered); Coastal Swamp Oak ( Casuarina glauca ) Forest of New South Wales and South East Queensland ecological community (Endangered) .

Conservation status.— AOO and EOO were calculated at 1,928 km 2 and 37,819 km 2, respectively. The estimates for AOO potentially qualify the taxon as Vulnerable. There is lack of evidence of population fragmentation, decline, or severe fluctuation to assess L. superciliaris for an extinction risk category and so a listing of Least Concern is applicable. However, concern for the species conservation status is warranted given its distribution is centered largely within threatened and fragmented vegetation communities of the Sydney Basin, one of Australia’s most urbanized regions.

Ecology.— Males congregate and call around static-water wetlands, wallums, swamps, and dams where they call while floating in water or secreted beneath vegetation at the water’s edge. According to FrogID data, the species is most often recorded calling from streams, creeks, and dams. The peak calling period is from September to November, with some reduced calling activity from December to March. The majority of FrogID recordings of L. superciliaris have been recorded in natural and rural areas, with few recordings from suburban and urban landscapes. Stomach contents of museum specimens included a wide variety of invertebrate prey, including spiders, centipedes, beetles, earthworms, and ants (predominantly Myrmecia spp. ). The species burrows into loose, sandy soils during unfavorable weather conditions and appears capable of remaining in aestivation for months at a time. For tadpole identification and development, see L. dumerilii grayi section in Anstis (2017).

Figures

FIG. 14. Holotype of Platyplectrum superciliare, ZFMK 28331. (A) Left-side profile, (B) hind foot, (C) dorsal profile, (D) ventral profile. Images copyright Morris Flecks, ZFMK, Germany.

FIG. 15. Images in life of Limnodynastes superciliaris. (A) AMS R.188161, male, South West Rocks, NSW. (B) AMS R.188207, male, lower Blue Mountains, NSW. (C) AMS R.188165, male, Agnes Banks, Cumberland Plains, NSW. (D) AMS R.188164, Harrington, mid-northern coast, NSW. (E) AMS R.188163, female, Laurieton, mid-northern coast, NSW. (F) AMS R.188135, juvenile, Hat Head National Park, mid-northern coast, NSW.

FIG. 10. Illustration of hind foot webbing extent, a useful diagnostic character for identification of the Limnodynastes dorsalis group. (A) Well-developed webbing (extends to beyond half-way between the 1st subarticular tubercle and tip of Toe 1), (B) moderate webbing (extends one-quarter to half-way between the 1st subarticular tubercle on Toe 1), (C) vestigial webbing (does not or only slightly extends beyond the 1st subarticular tubercle on the 1st Toe). Illustration copyright Alana de Laive.

FIG. 11. Examples of typical ventral color pattern, a useful diagnostic trait between members of the eastern Limnodynastes dorsalis group. (A) Limnodynastes terraereginae (CYP lineage), (B) L. grayi (WS lineage), (C) L. superciliaris (EC lineage), (D) L. dumerilii dumerilii, (E) L. dumerilii insularis, and (F) L. interioris. Specimen registration labels represent 25 mm.

FIG. 5. Map of sampled contact zones between the EC lineage (green) and L. dumerilii (gray), with STRUCTURE ancestry proportions for individuals indicated in pie charts. Labeled polygons are IBRA7 major biogeographic subregions.

FIG. 8. Comparison of the male advertisement calls of (A) WS lineage—Rockhampton, QLD (FrogID 312613), (B) EC lineage—Harrington, NSW (AMS R.188164), (C) CYP lineage—Finch Bay, Cooktown, QLD (QM J97862), (D) Limnodynastes dumerilii dumerilii—Tenterfield Creek, NSW (AMS R.188096), and (E) L. interioris —Narrandera, NSW (FrogID 276467). Audiospectrograms and oscillograms were produced in Raven Pro 1.6 with a fast-Fourier transformation of 512 points, and 50% overlap.