Boulenophrys cf. ombrophila (Messenger & Dahn, 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 cf. ombrophila

Fig. 3

Remark.

The following description is based on four tadpoles at Stages 25-27 (N = 3) and Stage 36 (N = 1). Body ratio ranges represent all specimens except where specified. Raw measurements are given in Table 1 .

Specimens examined.

CSUFT T10992 (Stage 25; field voucher: MT02; GenBank accession number: ON209283 ) collected on 3 June 2021; and CSUFT T10281 (Stage 26; field voucher: MT718; GenBank accession number: ON209275 ), CSUFT 10270 (Stage 36, field voucher: MT710; GenBank accession number: ON209267 ), and CSUFT T10272 (Stage 27, field voucher: MT712; GenBank accession number: ON209269 ) collected on 14 July 2021. All specimens were collected from Xiangsikeng (24.937705°N, 112.990257°E, ca. 1530 m, a.s.l.), Mangshan , Hunan Province, China .

External morphology.

The body is flattened and oval (BW/BL 52.9-54.8% at Stages 25-27, N = 3; and 51.0% at Stage 36, N = 1); 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 60.0-73.3% at Stages 25-27, N = 3; and 82.4% at Stage 36, N = 1); the internarial distance is smaller than interorbital distance (IND/IOD 65.8-68.2% at Stages 25-27, N = 3; and 66.7% at Stage 36, N = 1); the rims of nares are serrated, slightly raised from the body wall; the spiracle is sinistral, low on the left flank, and opens posterolaterally; the spiracle tube protrudes posteriorly, free from the body at the tip (SS/BL 54.9-59.6% at Stages 25-27, N = 3; and 56.0% at Stage 36, N = 1); 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 until reaching 2/3 of the tail length (TMH/MTH 45.8-53.3% at Stages 25-27, N = 3; and 48.3% at Stage 36, N = 1); the tail tip is usually sharply pointed (bluntly rounded in one small-sized specimen CSUFT T10992, Stage 25, TTL 20.9 mm); the tail length accounts for 72.4-75.6% of the total length at Stages 25-27 (N = 3), and 70.3% at Stage 36 (N = 1); the mouth is terminal and the oral disc is funnel-like (BW/ODW 61.5-69.2% at Stages 25-27, N = 3; and 61.4% at Stage 36, N = 1); three and four rows of short oval submarginal papillae are present on the upper and lower lips, respectively; keratodonts are absent; the upper jaw sheath is comb-like, exhibiting a small median notch, whereas 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 27 (CSUFT T10272, Fig. 3A-C ). In life, the background color of the body and tail is semi-transparent beige; 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; a dark spot is present between the eyes and followed by a short beige vertical line on the anterior dorsum; the neuromasts are distinctly visible; and sparse dark brown markings alongside the vertical line and the dorsolateral neuromasts. Laterally, the dorsal pattern extends to above the horizontal level of the spiracle; three large, whitish, and golden pigmented spots are present behind the eyes on each side of the lower part of head-body connection, two of them are visible from the ventral view; the lateral surface of the tail and fins is covered by irregularly shaped pale golden spots, interspersed with whitish chromocytes which form short lines, and brown chromocytes which gather into large spots along the tail muscle at the posterior part of the tail; the fins are semi-transparent; the anterior part of the dorsal fin is marbled with golden and dark brown speckles; the anterior part of the ventral fin and the anal tube exhibit minimal brown pigmentation whereas the rest of fins that exhibits sparse dark brown speckles. The ventral body skin is translucent beige, covered by dense milky white speckles; the gills and gut coils are indistinctly visible through the ventral skin. The oral disc is translucent beige; the lateral and middle wings are covered by orange pigmentation; the submarginal papillae on lips are dark brown; the narial rims are yellow; the eye sclera is silver with black dots; the iris is bright orange sprinkled with black dots; the spiracle is translucent, with scattered golden pigmentation.

Variation of coloration in life. Among the remaining three specimens examined, two tadpoles at Stages 26 and 36 match most of the coloration pattern of the description for CSUFT T10272 above (see Fig. 3E, F for ventral patterns). However, the dark spot between the eyes is not present in both; the vertical line is more distinct in CSUFT T10281, which extends from the middle of the eyes to the body-tail connection; and the vertical line in CSUFT T10270 is a bit longer than CSUFT T10272, which extend to the posterior dorsum. In the Stage 36 tadpole (CSUFT T10270), the hindlimbs are semi-transparent, and the legs are covered externally by brown chromocytes. A small-sized tadpole at Stage 25 (CSUFT T10992, TTL 20.9 mm) exhibited a significantly different coloration from other three tadpoles of larger body size (Stages 26-27, and 36; TTL 30.4-33.7 mm): the dorsal pattern is pale brown, with scattered dense dark melanocytes, especially at the vertebral line region; an inconspicuous orange V-shaped pattern between the anterior edges of the eyes and the median point of the upper lip; two orangish spots at the posterior edge of the eyes; the orangish pigmentation is also diffuse on the dorsal aspect of the body and tail; the ventral skin is almost clear, translucent milky, with sparse goldish speckles on the edge of the belly; the belly is covered with dense melanocytes, however, gut coils clearly visible through these melanocytes.

In preserved specimens, a fading of the dorsal pattern is observed; the golden spots on the lateral surfaces of the tail are not visible; the large spots on the anterior corner of the spiracle and gills become translucent, and the orange pigmentation on the lips disappears.

Comparisons.

The tadpoles of Bo. cf. ombrophila differ from the syntopic tadpoles of Bo. shimentaina by the semi-translucent beige background coloration of body and tail (vs. dark brown), a ventral pattern of dense milky white speckles on belly (vs. indistinct small speckles), and the pattern on tail of large spots along tail muscle (vs. dense markings posteriorly); from Bo. nanlingensis (see below for tadpole description) by the ventral pattern of dense whitish speckles (vs. sparse speckles), and the pattern on tail of several large spots (vs. many speckles).

Compared to other described Boulenophrys tadpoles where species identification is supported with molecular data, the tadpoles of Bo. cf. ombrophila differs by the ventral pattern of dense whitish speckles (vs. relatively sparse metallic blue speckles in Bo. fansipanensis ; sparse whitish speckles in Bo. jingdongensis ; sparse metallic grey blue speckles in Bo. hoanglienensis ; and scattered with silver tiny patches in Bo. lushuiensis ), and the tail pattern of several large spots along tail muscle (vs. few dark brown speckles in Bo. fansipanensis ; absence of large spots in Bo. jingdongensis ; many dark brown speckles in Bo. hoanglienensis ; small black spots in Bo. baishanzuensis ; few dark spots on posterior tail muscle in Bo. jiangi ; small black spots on tail muscle in Bo. leishanensis ; and dozens of small dark brown patches in Bo. lushuiensis ). Further comparisons between Bo. cf. ombrophila tadpoles and all megophryinid tadpoles that were identified based on molecular data are shown in Tables 2 , 3 .

Ecology notes.

One observed breeding site of Bo. cf. ombrophila was a relatively broad wetland crossed by a small shallow creek. Several water sources from the gentle slope of the bamboo forest fed this creek and made the entire area very wet. This breeding site was muddy, covered with leaf litter and fallen logs. The creek was narrow and slow flowing with maximum depth of 0.2 m. Some fallen logs blocked the creek and created still water areas. Only male Bo. cf. ombrophila and Q. exilispinosa were observed calling in this site during our visits from May to August, and in November. The potential predator of these frogs, an aquatic snake Opisthotropis cheni Zhao, 1999 which was observed once, in July, in this creek. A single small-sized tadpole specimen (CSUFT T10992, TTL 20.9 mm) at Stage 25 was collected from this site while the male frogs were heard calling before a heavy rainstorm on 3 June 2021 at 19:30 h at dusk. Three tadpoles were collected from the rocky area (Fig. 5B , mentioned above in the Bo. shimentaina section) 20 m downstream of this creek together with tadpoles of Bo. shimentaina and Bo. nanlingensis . Interestingly, male Bo. cf. ombrophila frogs were not observed calling in the rocky area, and the other two species did not breed in this wetland. This indicates a different microhabitat preference between these congeneric species. The breeding season of Bo. cf. ombrophila ends in mid-July in Mangshan. It is not clear if tadpoles will complete metamorphosis during the year.

Figures

Figure 3. Boulenophrys cf. ombrophila tadpoles A-C tadpole CSUFT T 10272 (Stage 27) lateral view, dorsal view, and ventral view in life D oral disc of tadpole CSUFT T 10270 (Stage 36) in preservative E ventral pattern of tadpole CSUFT T 10281 (Stage 26) in life; and F ventral pattern of tadpole CSUFT T 10270 (Stage 36) in life. E and F 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).