Boulenophrys nanlingensis (Lyu, Wang, Liu & Wang, 2019)

Qian, Tianyu, Li, Yonghui, Chen, Jun, Li, Pipeng & Yang, Daode, 2023, Tadpoles of four sympatric megophryinid frogs (Anura, Megophryidae, Megophryinae) from Mangshan in southern China, ZooKeys 1139, pp. 1-32 : 1

Boulenophrys nanlingensis

Fig. 4

Remark.

The following description is based on 14 tadpoles at Stages 25-29 (N = 12), and 34-35 (N = 2). Body ratio ranges represent all specimens except where specified. Raw measurements are given in Table 1 .

Specimens examined.

CSUFT T10144 (Stage 25; field voucher: MT04; GenBank accession number: ON209279 ) collected on 30 May 2021; and CSUFT T10302 (Stage 25, field voucher: MT722; GenBank accession number: ON209280 ), and CSUFT T10303 (Stage 25, field voucher MT723; GenBank accession number: ON209277 ) collected on 19 July 2021 from Tiantaishan (24.972277°N, 112.963394°E, ca. 1280 m a.s.l.); CSUFT T10261 (Stage 25; field voucher: MT701; GenBank accession number: ON209263 ), CSUFT T10262 (Stage 25; field voucher: MT702; GenBank accession number: ON209268 ), CSUFT T10273 (Stage 28, field voucher: MT703, GenBank accession number: ON209278 ), CSUFT T10991 (Stage 27; field voucher: MT711; GenBank accession number: ON209265 ), and CSUFT T10284 (Stage 25, field voucher: MT714; GenBank accession number: ON209271 ) collected on 14 July 2021; and CSUFT T10986 (Stage 35, field voucher: MT1106; GenBank accession number: ON209285 ) and CSUFT T10969 (Stage 34, field voucher: MT1109; GenBank accession number: ON209274 ) collected on 19 November, 2021 from Xiangsikeng (24.937705°N, 112.990257°E, ca. 1530 m, a.s.l.); and CSUFT T10376 (Stage 27, field voucher: MT756; GenBank accession number: ON209273 ), CSUFT T10377 (Stage 27, field voucher: MT757; GenBank accession number: ON209262 ), CSUFT T10378 (Stage 28, field voucher: MT758; GenBank accession number: ON209282 ), and CSUFT T10379 (Stage 29, field voucher: MT769; GenBank accession number: ON209266 ) collected on 28 July 2021 from Guizizhai (24.952750°N, 112.960470°E, ca. 1210 m a.s.l.), Mangshan, Hunan Province, China .

External morphology.

The body is elongated, oval, and flattened above (BW/BL 51.2-60.4% at Stages 25-29, N = 11; and 52.8-54.5% at Stages 34-35, N = 2); the eyes are located dorsolaterally, and the pupils are round; the nares are oval, closer to the eye than to the tip of the snout (NE/SN 55.6-80.0% at Stages 25-29, N = 12; and 57.9-62.5% at Stages 34-35, N = 2); the internarial distance is smaller than interorbital distance (IND/IOD 61.5-71.0% at Stages 25-29, N = 12; and 68.1-69.2% at Stages 34-35, N = 2); the nares open laterally; the rims of nares are serrated, slightly raised from the body wall; the spiracle is sinistral, low on the left flank, and opens posteriorly; the spiracle tube is short and slightly protrudes posteriorly (SS/BL 54.8-62.7% at Stages 25-29, N = 12; and 59.3-63.6% at Stages 34-35, N = 2). The anal tube opens medially and is unattached to the ventral fin; the dorsal fin arises behind the body-tail junction, and the ventral fin is connected to the trunk. The tail muscle is massive, deeper than tail fins before reaching the maximum tail height (TMH/MTH 43.4-63.0% at Stages 25-29, N = 11; and 50.7-54.5% at Stages 34-35, N = 2); the tail tip is pointed, the tail length accounts for 69.5-76.1% (at Stages 25-29, N = 11) and 73.1-74.4% (at Stages 34-35, N = 2) of the total length; the mouth is terminal and the oral disc is funnel-like (BW/ODW 63.3-79.6% at Stages 25-29, N = 12; and 73.1-85.7% at Stages 34-35, N = 2); four and five rows of short oval submarginal papillae can be observed on the upper and lower lips, respectively; keratodonts are absent; the upper jaw sheath is comb-like, exhibiting a weak median notch; the lower jaw sheath is thin and sickle-shaped, weakly keratinized, and finely serrated.

Coloration.

The following description is based on a tadpole at Stage 25 (CSUFT T10303, Fig. 4A-C ). In life, the background color of the body and tail are semi-transparent grey; the dorsal surface of the body is covered by a pale brown pattern that extends to the dorsal surface of the anterior part of the tail; roughly symmetrical dark brown pigmentation can be observed on the dorsal body; and the neuromasts are distinctly visible. Laterally, the dorsal pattern extends to above the horizontal level of the spiracle; the lateral surface of the tail is pigmented brown, interspersed with pale golden spots and irregular dark brown speckles; the fins are semi-transparent and scattered with pale golden spots; the anterior part of the dorsal fin is marbled with golden and dark brown speckles, with the dark brown speckles forming an incomplete line; the anterior part of the ventral fin and the anal tube, lacks brown pigmentation but with sparse golden speckles. The ventral surface of the body is semi-transparent grey; the gills appear pink through the ventral skin; two large gold-pigmented white spots are present at ventrolateral head-body connection; the gut coils are distinctly visible through the ventral skin, the belly is scattered with small whitish speckles; the oral disc is translucent beige; the lateral and middle wings are covered by orangish pigmentation; the submarginal papillae on lips are dark brown; the narial rims are beige; the eye sclera is silver with black dots; the iris is copper-colored sprinkled with black dots, comparable to the iris coloration in adults; and the spiracle is translucent.

Variation of coloration in life. The dorsal pattern coloration in tadpoles of Bo. nanlingensis is subject to significant variation both in same stages and between stages. At Stage 25, a small-sized tadpole (CSUFT T10144, TTL 18.7 mm) exhibits a yellowish dorsum with pale orange blotches, and dark brown pigmentation present posteriorly; another small tadpole (CSUFT T10284, TTL 18.9 mm) displays a brown dorsum with whitish patterns on the dorsolateral surfaces of the trunk and these extend to the tip of the tail. The coloration of the medium-sized tadpoles at Stage 25 (CSUFT T10261, TTL 25.1 mm; and CSUFT T10262, TTL 27.2 mm) and a broken-tailed individual at Stage 25 (CSUFT T10302) correspond to the dorsal pattern of CSUFT T10303 described above. However, the shape and coverage of dark brown markings varies between individuals. At later Stages 27-29, three medium-sized tadpoles (CSUFT 10377, Stage 27, TTL 28.1 mm; CSUFT T10376, Stage 27, TTL 24.8 mm; and CSUFT 10378, Stage 28, TTL 26.9 mm) exhibit a bi-colored dorsum, which is anteriorly pale brown and posteriorly inconspicuous dark brown. Tadpoles with relatively larger size at both early Stages 27-28 and advanced Stages 34-35 (CSUFT T10273, Stage 28, TTL 35.7 mm; CSUFT T10991, Stage 27, TTL 39.1 mm; CSUFT T10986, Stage 35, TTL 40.1 mm; and CSUFT T10969, Stage 34, TTL 34.4 mm) exhibit a uniform brownish dorsum coloration with almost invisible markings. Two tadpoles, CSUFT T10144 (Stage 25, TTL 18.7 mm) and CSUFT T10379 (Stage 29, TTL 27.8 mm) exhibit pale yellowish dorsum with orange pigmentation, which are indistinguishable from the small-sized Bo. cf. ombrophila tadpole (CSUFT T10992, TTL 20.9 mm). A tadpole at Stage 27 (CSUFT T10376, TTL 24.8 mm) with a mid-vertical line on dorsum is similar with that of larger Bo. cf. ombrophila tadpoles (Stages 26-27, and 36; TTL 30.4-33.7 mm). However, they were not collected form the same site as Bo. cf. ombrophila tadpoles. A large-sized tadpole at Stage 35 (CSUFT 10986, TTL 40.1 mm) showed a ventral pattern of large spots on belly that was different with other specimens. For tadpoles at Stages 34-35 (CSUFT T10969, and CSUFT T10986), the hindlimbs are semi-transparent, the outer aspect of the legs is pigmented yellow and interspersed with brown chromocytes on top.

In preserved specimens, a fading of the dorsal pattern is observed; the tail is translucent with sparse dark-brown pigmentation; the orange pigmentation on lips is no longer visible; the whitish speckle on the ventral surface and the nares are translucent.

Comparisons.

The variation of dorsum pattern makes the tadpoles of Bo. nanlingensis are sometimes confused with the syntopic tadpoles of Bo. cf. ombrophila . Usually, the ventral pattern of sparse speckles (vs. dense speckles) and the tail pattern of many small speckles (vs. large spots) could distinguish them. An exception is the small-sized tadpole CSUFT 10144 (Stage 25, TTL 18.7 mm), which bears almost the same pattern as a small-sized Bo. cf. ombrophila tadpole CSUFT T10992 (Stage 25, TTL 20.9 mm). The tadpoles of Bo. nanlingensis differ from the syntopic Bo. shimentaina tadpoles by the pale brownish background coloration of the body and tail (vs. dark brown), the ventral pattern of sparse speckles (vs. dense small speckles), and the tail pattern of small dots (vs. large speckles).

Compared to other described Boulenophrys tadpoles where species identification is supported by molecular data, the tadpoles of Bo. nanlingensis differs by the presence of ventrolateral spots on each side of head-body connection (vs. absent in Bo. jingdongensis , Bo. hoanglienensis , Bo. leishanensis , and Bo. lushuiensis ); the tail pattern of many brown speckles (vs. small spots on tail muscle in Bo. leishanensis ; few dark spots on posterior tail muscle in Bo. jiangi ; and small white and black dots in Bo. baishanzuensis ). Further comparisons between Bo. nanlingensis tadpoles and all megophryinid tadpoles that were identified based on molecular data are shown in Tables 2 , 3 .

Ecology notes.

Tadpoles of Bo. nanlingensis were discovered in all collection sites during our field surveys in 2021, which perhaps implies that this species has larger population size, or it might exhibit less microhabitat specificity. Besides the three sites mentioned above, four Bo. nanlingensis tadpoles were collected from a relatively wide stream (3-5 m wide), with a maximum depth of 0.5 m. An adult male was observed calling under rocks near the stream bank with its feet standing in shallow water on 28 July 2021.

The male calling activities of Bo. nanlingensis , which began in late July, had increased during our visit in November in Mangshan. It seems the newborn larva would have to over-winter. Thus, we suspected the tadpoles of early Stages 25-29 collected in May and July were born in the previous year. Two tadpoles at advanced Stages 34-35 were collected on the 19th of November. Considering tadpoles in late stages develop relatively fast (Grosjean, 2003; TQ, personal observation). It was likely these advanced tadpoles would finish metamorphosis in cold season at the beginning of the next year. However, this assumption needs further confirmation because the cold weather and scarce food in winter may not be suitable for the survival of froglets.

Figures

Figure 4. Boulenophrys nanlingensis tadpoles in life A-C tadpole CSUFT T 10303 (Stage 25) lateral view, dorsal view, and ventral view D ventral pattern of tadpole CSUFT T 10262 (Stage 25) E ventral pattern of tadpole CSUFT T 10273 (Stage 28); and F oral disc of tadpole CSUFT T 10261 (Stage 25). D and E share the same scale bar with A-C.