Kalophrynus interlineatus ( Blyth, 1855 ) Striped Sticky Frog

Zug, George R., 2015, Morphology and Systematics of Kalophrynus interlineatus-pleurostigma Populations (Anura: Microhylidae: Kalophryninae) and a Taxonomy of the Genus Kalophrynus Tschudi, Asian Sticky Frogs, Proceedings of the California Academy of Sciences 62 (5), pp. 135-190 : 161-164

Kalophrynus interlineatus ( Blyth, 1855) Striped Sticky Frog

Figures 7 , 11C .

Engystoma (?) interlineatum Blyth, 1855, Journal of the Asiatic Society of Bengal [1854] 23:732 [type locality: “ Pegu ”, Myanmar; see Comments below] .

TYPE MATERIAL.— LECTOTYPE: Natural History Museum United Kingdom, formerly British Museum of Natural History 68.4.3.128, recataloged as 1947.2.31. 26 . PARALECTOTYPE: NHMUK / BMNH 68 .4.3. 129, recataloged as 1947.2.31. 27. See discussion on the assignment of type specimens in the Comments section below .

DESCRIPTION AND INTRAPOPULATIONAL VARIATION. Moderate-sized adults, not sexually dimorphic although females average larger (mean 41.5, 35.0–46. 4 mm SVL) than males (39.2, 33.7–44. 6 mm). These differences are reflected in the other measurements: HeadL 11.2–15. 3 mm ♀♀ , 10.3–13. 4 mm ♂♂; HeadW 12.7–15. 1 mm ♀♀, 11.3–13. 5 mm ♂♂; SnEye 4.3–5. 7 mm ♀♀, 3.8– 5.3 mm ♂♂; NarEye 2.8– 3.7 mm ♀♀, 2.3– 3.8 mm ♂♂; EyeD 3.6– 4.5 mm ♀♀, 3.4– 4.5 mm ♂♂; Tymp 3.1–3. 8 mm ♀♀, 2.6– 3.5 mm ♂♂; ForarmL 9.0–13. 2 mm ♀♀, 8.7–12. 2 mm ♂♂; HandL 8.4–11. 3 mm ♀♀, 7.7–10.0 mm ♂♂; ThghL 13.7–18. 6 mm ♀♀, 14.1–17. 7 mm ♂♂; CrusL 13.0–16. 2 mm ♀♀, 12.0–15. 6 mm ♂♂; TarsL 8.5–10. 4 mm ♀♀, 7.9–10. 8 mm ♂♂; HndfL 13.0–16. 6 mm ♀♀, 11.7–15. 8 mm ♂♂. Body proportion means differ between females and males, although not greatly so (all values are percent): HeadL/ SVL 29– 36 ♀♀ , 28– 31 ♂♂; HeadW/ SVL 31– 36 ♀♀ , 29– 36 ♂♂; HeadW/HeadL 95– 11 ♀♀, 95– 116 ♂♂; SnEye/HeadL 36– 41 ♀♀, 36– 45 ♂♂; NarEye/SnEye 56– 66 ♀♀, 54– 78 ♂♂; EyeD/HeadL 28– 36 ♀♀, 30– 37 ♂♂; Tymp/EyeD 72– 100 ♀♀, 71– 79 ♂♂; Forarm/ SVL 25– 31 ♀♀ , 24– 31 ♂♂; Forarm/CrusL 69– 83 ♀♀, 65– 86 ♂♂; HndlL/ SVL 127– 147 ♀♀ , 122– 148 ♂♂; CrusL/ SVL 34– 40 ♀♀ , 30– 39 ♂♂; CrusL/ThghL 83– 95 ♀♀, 81– 96 ♂♂; TarsL/ThghL 51– 62 ♀♀, 53– 63 ♂♂; HndfL/ SVL 30– 40 ♀♀ , 30– 40 ♂♂; HndfL/ThghL 84– 95 ♀♀, 80– 93 ♂♂.

I noted earlier in the Morphometric section that the Tanintharyi sample displayed no significant sexual dimorphism and that females were significantly larger in the SE Asia sample. When the samples are combined, the overall size dimorphism declines, although a few traits remain dimorphic. Females have larger heads than males; HeadL, HeadW, and SnEye average larger, but none of the other head metrics do, and there are no proportional differences in the head or body metrics. There is strong dimorphism in ForarmL and HndfL with females being larger in both.

In their amphibian atlas, Fei et al. (2010) reported Chinese males as 32–38 mm SVL and females to 40 mm. These adult lengths are smaller, likely significantly so, than my sample which is comprised of frogs from more southern locations. Karsen et al. (1986) did not give a range or mean for Hong Kong K. interlineatus and his “up to 6 cm long”, contrasts sharply with Fei’s lengths and is much larger than the maximum SVL in our sample or that reported for this species elsewhere. Bourret (1942) gave single value adult sizes of 38 mm SVL for males and 44 mm for females. Berry (1975) gave total lengths of Peninsular Malaysia K. interlineatus as 47–58 mm. I interpret his total length as SVL, hence his size data are greater than the range for my Tanintharyi and Thai-Indochina samples and more closely match the size of K. meizon . Although I do not reject his data, I am uncertain how to interpret it and have not included his values in Table 3. Manthey and Grossmann (1997), in contrast, gave 35–41 mm SVL for males and 38–46 mm for females from Peninsular Malaysia, matching my adult size range for the Tanintharyi and Thai-Indochina samples. A more recent study of Malaysian K. interlineatus ( Chan et al, 2011) reported 33.7–38. 1 mm SVL for adult males (n = 7) and 41.1–47. 3 mm SVL for adult females (n =10); these values also match my values for the more northern Thai-Indochinese sample.

Tongue is broadly obovate, posterior edge smooth; vomerine teeth are absent; palatal fold morphology appears relatively uniform among individuals although these data are not quantified. Vomerine folds are smoothedged flaps, one adjacent to each choanae and widely separated from its opposite. Postorbital folds are more variable; in Tanintharyi frogs, a pair of folds is separated on the midline, and each side has two or three. Variation in the Thai and Indochina frogs is described in the morphology section. Buccal fold is a continuous lobular fold with abutting lobes and each lobe a low, round-edged rectangle. See Fei et al. (2005) for an illustration of the buccal cavity of a Chinese K. interlineatus.

Fingers lack webbing. Both finger and toe tips are bluntly rounded. Subarticular tubercle are well developed on the digits; only third finger bears a subarticular tubercle on free portion of digit; all fingers have a tubercle at their base and another row between a large, circular, nearly medial outer palmar tubercle. For the hindfoot, each toe has a basal subarticular tubercle, third and fifth toes have an addition tubercle on free portion of digit, two tubercles on fourth toe. Inner and outer metatarsal tubercles are present; inner is large, nearly circular to elliptical; outer small to nearly absent and circular. Toes modestly webbed WebIII2 median 2.0 (1.0–3.0), WebIV1 1.0 (0.5–2.0). Digit lengths nearly constant for fore- and hindfeet; finger formula 3>2≈1>4; toe formula 4>3>5>2>1.

Color pattern variation statistics for entire sample of juvenile and adults are (median and range): HeadMid 1, 0–2; HeadPsag 0, 0–2; DorsNap 1, 0–2; DorsPsag 1, 0–2; IngSpt 2, 0–2; HndlBr 2, 0–2; DlatSt 2, 1–2; Loreal 2, 0–2; LatTrnk 2, 0–2; Chin 2, 0–2; Chest 1, 0–2. In summary, K. interlineatus usually has a faded to distinct middorsal stripe and no parasagittal stripes on head, distinct nape stripe in about half of the individuals continuing into bilateral (parasagittal) stripes, inguinal spot almost always present and usually as ocelli, dorsolateral narrow white stripe rarely absent or indistinct, hindlimbs almost always distinctly barred, loreal area and lateral trunk usually uniformly dark, chin and throat always dusky and usually with pair of darker longitudinal bars, and chest commonly dusky. Dorsal ground color is variable, ranging from a light beige or tan to medium or rufous brown, occasional individuals are rose to pink; sides from lore to inguinal are usually shades of medium to dark brown.

Fei et al. (2010) provided color images of five living individuals whose dorsal coloration ranged from unicolor [n = 1 individual] to strongly patterned with all six of my dorsal pattern characters strongly developed [n = 5]. The dorsal stripe pattern of Chinese K. interlineatus has the same layout/arrangement; however, the stripes differ markedly in being broader with strongly scalloped edges and fragmented, especially the DorsPsag ones. Karsen et al. (1986) pictured a Hong Kong striped individual that matched those of Fei et al. Additionally Fei’s photographs showed well-developed white dorsolateral stripes that were strongly speculate in all individuals. The single individual depicted for Cambodia (Thy and Holden 2008) had a well-developed dorsal pattern similar to the western populations, although the white dorsolateral stripe was narrow and appeared interrupted. Ohler and Grosjean (2005) reported distinct pattern difference between “western” and Vietnamese frogs. The former depicted by a Laos individual (O&G 2005: figs. 1a,c,e) has straight-edged dorsal stripes, the latter (2005: figs. 1b,d,f) has the scalloped and fragmented stripes of the Chinese individuals. The preceding summary confirms Ohler’s and Grosjean’s observations of color pattern differences between west ( Thailand) and east ( Vietnam) and, as they noted, hints at the possibility of speciation between eastern and western populations. Chan and collaborators (2011) noted that half of their sample of Malaysian K. interlineatus (= their pleurostigma ) lacked inguinal spots on one or both sides and concluded that “populations in Peninsular Malaysia are not conspecific” with mainland Asia populations. Their interpretation may be correct, although I suspect that there is no genetic discontinuity between these Malaysian population and those of peninsular Myanmar and Thailand.

ETYMOLOGY.— Blyth (1855) offered no explanation for his name, presumably using interlineatus to note the longitudinal lines on the dorsum, hence a derivation from the Latin inter, between, and lineatus, from Latin lineo, drawing lines, and linearis, lineatus, of a line, linear.

DISTRIBUTION.— Kalophrynus interlineatus as here defined has the broadest geographic range of the pleurostigma group, extending eastward from northern-most Peninsular Myanmar, eastward through northern Thailand, Laos, Cambodia, and Vietnam, southward through Peninsula Malaysia, and also in southern China from southeastern Yunnan to Hong Kong and adjacent Guangdong.

Bourret’s (1942) concept of K. interlineatus was as a subspecies with a northern distribution from Myanmar through northern Thailand to Vietnam and adjacent China to Hong Kong. He had only a single male specimen (38 mm SVL) of questionable locality (probably Tonkin, Vietnam) in Indochina. He listed four Burmese localities: Bhamo, Teinzo, Palon, Toungo (credited to Oates [Toungo] and Fea [diverse localities]). The first two records are potential localities for K. anya , the latter two are potential localities for K. interlineatus . Toungo (= Taungo, 20°56´N 95°24´E) is in the upper Sittaung River valley. MNHN 1893.492 is identified as Kalophrynus interlineatus from Palon; I did not examine this specimen to confirm its presence or identification. Palon (7°41´N 97°31´E), Kayin State, is identified as a Pegu locality in the British natural history museum specimen register but represented by only one gecko and one Micryletta inornata . This record highlights the broad geographic concept of Pegu by the British in late 19 th century.

Thy and Holden (2008) stated that K. interlineatus was a common frog and suggested that it occurred throughout Cambodia.

NATURAL HISTORY.— In Cambodia, Thy and Holden (2008) reported it as a common species living in grassland, scrub forest adjacent to villages, and deciduous forest. The recent Burmese individuals derived from the soil surface in mixed deciduous-evergreen secondary growth forest (Mon) and from evergreen forest abutting a clear-cut (weedy) pipeline (Tanintharyi).

COMMENTS.— The type locality “Pegu” is commonly interpreted by biologists as equivalent to the present Myanmar division of Bago (formerly called Pegu). Nineteenth century Pegu encompassed a much broader area than the present political division. The older Pegu encompassed the area from the Arkan (roughly equivalent to the present state of Rakhine) eastward to the Sittang River drainage. This broad Pegu likely encompassed northernmost Mon State, hence my placement of the type locality straddling the Bago-Mon border. This broad Pegu is emphasized by a NHMUK / BMNH specimen from Palon , Kayin state, that was geographically labeled as Pegu.

Ohler and Grosjean (2005) reported examining the holotype of Engystoma interlineatum Blyth , a specimen ( ZSI 9853) from Mergui, Myanmar. The British Museum has two specimens ( NHMUK / BMNH 68.4.3.128–129, recataloged as 1947.2.31. 26–27, an adult female and male, respectively) collected by Theobald in Pegu. I believe that the latter two Pegu specimens of Theobald’s ( Fig. 7 ) are the individuals on which Blyth based his description of interlineatum , and they were subsequently sent to London. The precision of ZSI locality indicates that someone arbitrarily selected a Kalophrynus specimen and designated it as a ZSI holotype. Mergui was never recognized as part of Pegu and is in Tenasserim. Because both Blyth (1855:720) and Theobald (1882: 192) specifically noted having two specimens, I recommend recognizing one of them as a lectotype and select BMNH 1947.2.31. 26, the female, because this specimen is presently in the best physical condition. BMNH 1947.2.31. 27 is then a paralectotype. Because Pegu is not sufficiently delimited, I recommend a more precise, yet not overly restrictive, type locality: Bago DivisionMon State border in the lower Sittaung River valley, Myanmar (~ 17°35´24˝N 96°53´33˝E).

Figures

FIGURE 7. Images of lectotype of Kalophrynus interlineatus (NHMUK/BMNH 1947. 2.31.26, female) in (A) dorsal and (B) ventral views, and of paralectotype (NHMUK/BMNH 1947. 2.31.27, male) in (C) dorsal view [photographer G.R. Zug].

FIGURE 11. Coloration of living representatives of pleurostigma-interlineatus group. (A) Dorsolateral view of a K. anya (USNM 520321) from the Chatthin Wildlife Sanctuary, Sagaing, Myanmar [photographer, C. Hansen]; (B) dorsolateral view of a K. anya (USNM 523966) from the Chatthin Wildlife Sanctuary, Sagaing, Myanmar [photographer, G.R. Zug]; (C) dorsolateral view of a K. interlineatus (CAS) from the Tanintharyi National Park, Tanintharyi, Myanmar [photograph- er, J.V. Vindum]; (D) dorsolateral view of a K. meizon (FMNH 242796) from Poring Station, Mt. Kinabulu Park, Ranua District, Sabah [photographer, R.F. Inger]; (E) dorsolateral view of a K. sinensis (UK 333148) from Agusan del Norte, Mindanao, Philippines [photographer, R.M. Brown]; (F) dorsolateral view of a K. pleurostigma (UK 333148) from Gunung Kunyit, Jambi, Sumatra [photographer, E.N. Smith].