Brachytarsophrys popei, Zhao, Yang, Chen, Chen & Wang, 2014

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

Brachytarsophrys popei

Fig. 1

Remark.

The following description is based on five tadpoles at Stages 26-27 (N = 2) and 36-37 (N = 3). Body ratio ranges represent all specimens. Raw measurements are given in Table 1 .

Specimens examined.

CSUFT T10115 (Stage 37, Field voucher: MT05; GenBank accession number: ON209276 ), CSUFT T10117 (Stage 37; Field voucher: MT07; GenBank accession number: ON209284 ), and CSUFT T10119 (Stage 36; Field voucher: MT09; not sequenced), collected on 30 May 2021 from Tiantaishan (24.972277°N, 112.963394°E, ca. 1280 m a.s.l.), Mangshan , Hunan Province, China; and CSUFT T10944 (Stage 27, Field voucher: MT1104; not sequenced), and CSUFT T10945 (Stage 26; Field voucher: MT1105; not sequenced), collected on 16 November 2021 from the same site as the first specimens .

External morphology.

The body is oval, robust, and flattened above (BW/BL 53.3-55.7% at Stages 26-27, N = 2; and 53.6-55.2% at Stages 36-37, N = 3); the head is wider than the trunk; the eyes are located dorsolaterally, the pupils are round; the nares are oval, opening laterally, closer to the eye than to the tip of the snout (NE/SN 68.8-73.3% at Stages 26-27, N = 2; and 73.7-83.3% at Stages 36-37, N = 3); the internarial distance is smaller than the interorbital distance (IND/IOD 65.8-68.4% at Stages 26-27, N = 2; and 59.6-63.8% at Stages 36-37, N = 3); the rims of nares are raised from the body wall and directed posterolaterally; the spiracle is sinistral and low on the left flank; the spiracle tube is short, protruding posterodorsally, free from the body at the tip, and opening posterolaterally (SS/BL 55.6-62.0% at Stages 26-27, N = 2; and 57.3-58.1% at Stages 36-37, N = 3); the anal tube opens medially, unattached to the ventral fin; the dorsal fin arises behind the body-tail junction while the ventral fin is connected to the trunk; the tail muscle is massive, taller than tail fins before reaching the maximum tail height (TMH/MTH 55.6-55.8% at Stages 26-27, N = 2; and 48.4-50.8% at Stages 36-37, N = 3), and the tail tip is bluntly pointed, the tail length accounts for 71.7% (at Stages 26-27, N = 2) and 70.5-70.5% (at Stages 36-37, N = 3) of the total length; the mouth is terminal and the oral disc is funnel-like (BW/ODW 74.6-88.9% at Stages 26-27, N = 2; and 75.6-78.4% at Stages 36-37, N = 3); three and four rows of short oval submarginal papillae can be observed on the upper lip and lower lip, respectively; keratodonts are absent; the upper jaw sheath is brush-like, exhibiting a small median notch, while the lower jaw sheath is thin, sickle-shaped, weakly keratinized, and finely serrated.

Coloration.

In life, the background color of the head and trunk is dark brown; the dorsal pattern is pale brown interspersed with dark brown chromocytes, extending to above the horizontal level of the spiracle on the trunk from a lateral perspective; the dorsal surface of the anterior part of the tail is pale brown marbled with dark brown speckles; neuromasts are distinctly visible on the head, trunk and tail; the region between the anterior edges of the eyes and the median point of the upper lip is pigmented with a dark brown V-shaped pattern; the narial rims are pale brown; the oral disc is golden-pigmented, with a translucent edge; the submarginal papillae on lips are dark brown-pigmented. Laterally, the tail is pale brown-pigmented; dense goldish spots are located at the anterior part of the lateral surface of tail muscle, becoming smaller and at the middle, then disappearing posteriorly; three distinct dark brown stripes extended from the body-tail junction, and horizontally positioned at the anterior part of the tail; the upper and lower stripes end before reaching the maximum tail height, while the middle stripe is about half the length of the others; the upper and middle stripes are incomplete; the anterior part of the upper fin is opaque, marbled with goldish pigmentation and brown speckles; the anterior part of the ventral fin, as well as the anal tube are semi-translucent with dense large golden spots; the rest of the fins are semi-translucent, and exhibit sparse dark brown speckles interspersed with small goldish dots. The ventral surface of the body is rather dark; the belly is dark purplish covered with dense white spots; two longitudinal stripes, positioned ventrolaterally, extending from the snout to the vertical edge of the eyes posteriorly, and sometimes appear to broken; a transverse bar is positioned at the head-trunk junction of the vertical edge of the anterior spiracle and is always interrupted at the middle; the spiracle region and the corresponding region on the other side of the body, are covered with a short white stripe, that starts from the head-body connection, and terminated before reaching the region of the spiracle tube opening; regions without white pigmentation have less melanocytes; the gills and gut coils are indistinctly visible through the ventral skin. The eye sclera is silver with black dots; the iris periphery is wide and black; the iris is golden sprinkled with black dots; and the spiracle is translucent without pigmentation. In tadpoles at Stages 36-37, the hindlimbs are semi-transparent, and the outer aspect of the legs exhibits brown pigmentation interspersed with goldish chromocytes.

In preserved specimens, the tail stripes are still prominent; an incomplete V-shaped pigmentation pattern is still visible; the ventral pattern is translucent milky white; the golden pigmentation wanes on the oral disc; and the hindlimb bones are visible in ventral view in Stage 36-37 tadpoles.

Comparisons.

Tadpoles of Br. popei differ significantly from the three syntopic Boulenophrys tadpoles described below by the unique pattern of two longitudinal white ventrolateal stripes on head, a transverse white bar on chest, and distinct large spots on belly (vs. absence of stripes and bars, and smaller spots/speckles on belly).

The differences in ventral pattern between four Brachytarsophrys tadpoles were compared by Li et al. (2020) and summarized in Table 2 . The tadpole of Br. popei (Stage 29, N = 1) illustrated in their paper (also in Zhao et al. 2014, but marked as Stage 27), which was collected ~ 200 km north of Mangshan has a complete transverse white ventral bar. In contrast, our tadpoles (Stages 26-27, N = 2; and Stages 36-37, N = 3) consistently exhibit an interrupted white transverse ventral bar. This difference may be due to geographic variation or insufficient sample size. However, the presence of a transverse bar on chest could distinguish Br. popei tadpoles from Br. orientalis and Br. intermedia (vs. absent in both). In addition, the width of the transverse bar is markedly smaller than that in Br. chuannanensis (see Li et al. 2020: fig. 5E, F). Furthermore, compared with Br. intermedia , the tadpoles of Br. popei have a distinctly smaller size at Stage 36 (TTL 36.9 mm vs. 48.7 mm). Zhao et al. (2014) illustrated a metamorph of Br. feae at Stage 44 with several short stripes on belly (vs. spots or speckles in Br. popei , Br. orientalis , and Br. chuannanensis ). We believe this pattern should be confirmed using more specimens at an earlier developmental stage in case this is a transitional form during metamorphosis. Further comparisons between Br. popei tadpoles and all megophryinid tadpoles that were identified using molecular data are shown in Tables 2 and 3 .

Ecology notes.

All tadpoles were collected from an artificial roadside drainage ditch (Fig. 5C ) at night while feeding beneath the water surface. Upstream of the ditch is a narrow, slow-moving stream with many rocks covered by moss. The ditch was rocky with a sandy substrate. The maximum depth of this ditch was ~ 0.5 m. Branches of plants from the mountain side of the road extended over this ditch, however, sunlight did reach the water surface at certain times of the day. Tadpoles were observed in a still water stretch behind big rocks, or a small dam formed by submerged leaf litter. Three tadpoles at Stages 36-37 were collected on 30 May 2021 at 22:30 h, together with tadpoles of Bo. shimentaina and Bo. nanlingensis with an ambient air temperature of ~ 20 °C. Two tadpoles at Stages 2627 were collected on 16 November 2021 at 19:30 h with an ambient temperature of ~ 13 °C. Tadpoles were considered nocturnal because we did not encounter any tadpoles during the day. Male Br. popei frogs began their calling activities under rock crevices in this ditch in late July. Zhao et al. (2014) reported that the breeding season of Br. popei is July to September, and that their tadpoles (Stages 26-29) were collected in April and December. This indicates that the development of these tadpoles may be very prolonged, and it is likely that they can over winter. Interestingly, it is unknown why no tadpoles were collected during the breeding season both in this study and in Zhao et al. (2014).

Figures

Figure 1. Brachytarsophrys popei tadpoles in life A-C tadpole CSUFT T 10117 (Stage 37) lateral view, dorsal view, and ventral view D ventral pattern of tadpole CSUFT T 10119 (Stage 36) E ventral pattern of tadpole CSUFT T 10945 (Stage 26); and F oral disc of tadpole CSUFT T 10117 (Stage 37). D and E share the same scale bar with A-C.

Figure 5. Megophryinid tadpoles and their habitats in Mangshan, Hunan Province, China (A) Non-collected Bo. shimentaina tadpole (middle) feeding together with two unrecognized tadpoles in its habitat (B); and tadpole habitat (C) of a mixed-species assemblage beside a forest road, with unrecognized tadpoles feeding together (D).