Lepidocephalichthys zeppelini Havird & Tangjitjaroen, 2010

Havird, Justin C., Page, Lawrence M., Tangjitjaroen, Weerapongse, Vidthayanon, Chavalit, Grudpan, Chaiwut & Udduang, Suriya, 2010, A new species of Lepidocephalichthys (Teleostei: Cobitidae) with distinctive sexual dimorphism and comments on relationships in southern lineages of Cobitidae, Zootaxa 2557 (1), pp. 1-18 : 6-13

Lepidocephalichthys zeppelini Havird & Tangjitjaroen , new species

( Fig. 1 ; Tables 2–5)

Holotype. UF 174131, 21.1 mm-SL male, Thailand, Ubon Ratchathani, Mun River (tributary of Mekong River), isolated pools in a rice field, Ubon Rajathanee University campus, 15°8’3.18”N, 104°55’27.78”E, 10 June 2008, L. M. Page, W. Tangjitjaroen, S. Udduang, and J. C. Havird.

Paratypes. CAS 219335 , 8 males, 37 females, 17.0– 25.8 mm SL, Thailand, Ubon Ratchathani market, ~ 15°9'23.73"N, ~ 105° 3'27.81"E, 11–13 Sept. 1990 , T. R. Roberts . NIFI 3248 , 1 male, 8 females, 15.5–23.1 mm SL, Thailand, Nong Khai, Beung Kan, Goot Ting marsh, ~ 18°13'34.15"N, ~ 103°39'0.33"E, 11 June 2003, C. Vidthayanon . NIFI 3249 , 1 male, 8 females, 15.9–20.0 mm SL, Thailand, Nong Khai, Beung Kan, Goot Ting marsh, ~ 18°13'34.15"N, ~ 103°39'0.33"E, 23–27 March 1996, C. Vidthayanon . UF 171981, 3 juveniles, 11.3–12.7 mm SL, Thailand, Ubon Ratchathani, Mun River (tributary of Mekong River ), rice field, 15°8’17.76”N, 104°55’30.54”E, 9 June 2008, L. M. Page, W. Tangjitjaroen, and J. C. Havird, GenBank GQ174345 , GQ174347 , GQ174383 , GQ174399 . UF 171983, 1 juvenile, 12.7 mm SL, Thailand, Amnat Charoen, Mekong drainage, small sandy stream, 15°54’13.56”N, 105°11’17.28”E, 10 June 2008, L. M. Page, W. Tangjitjaroen, and J. C. Havird . UF 174130, 10 males, 18 females, 4 juveniles, 12.1–22.8 mm SL, data as for holotype, GenBank GQ174346 , GQ174348 – 51, GQ174384 , 5. UF 174132, 1 female, 15.7 mm SL, Thailand, Ubon Ratchathani, Mun River (tributary of Mekong River), marsh near Ubon Rajathanee University campus, 15°10’45.84”N, 104°45’44.76”E, 10 June 2008, L. M. Page, W. Tangjitjaroen, and J. C. Havird . UMMZ 227583 , 11 males, 22 females, 15.0– 23.3 mm SL, Vietnam, Long Xuyen, Mekong drainage, rice paddy NW Long Xuyen , ~ 10°23'22.49"N, ~ 105°24'56.46"E, 22 July 1974, Rainboth, Smith, and Weidenbach . ZRC 51882, 3 , 17.0– 22.9 mm SL, data as for holotype .

Diagnosis. A species of Lepidocephalichthys sensu Havird & Page (2010) . Lepidocephalichthys zeppelini is distinguished from other Lepidocephalichthys by having the 7–8th pectoral-fin rays of the mature male having a large (extending along> 75% of the length of the 7–8th pectoral rays) dorsally projecting, rounded rectangular flange with about 25 fine serrations and a smaller ventrally projecting, rounded flange ( Fig. 1C, D ); a forked caudal fin; small barbels (not reaching orbit); dark reticulations on caudal fin; and small size (to 25.8 mm SL).

Comparisons. Lepidocephalichthys zeppelini is distinguished from all other Lepidocephalichthys by having the 7–8th pectoral-fin rays forming a large, dorsally projecting, rounded rectangular flange and a smaller (although large compared to the dorsal projections of other species), ventrally projecting rounded flange ( Fig. 1C, D ). It is also distinguished from all other species of Lepidocephalichthys by its small adult body size (to 25.8 vs. 30.8 mm SL).

The new species is further distinguished from all other congeners except L. manipurensis Arunkumar , L. furcatus (de Beaufort) , L. goalparensis Pillai & Yazdani , and L. micropogon (Blyth) by its forked (vs. rounded or truncated) caudal fin. It is distinguished from L. micropogon , L. goalparensis , and L. manipurensis by its darkly reticulated (vs. barred) caudal fin, and from L. furcatus by having fine serrations (vs. smooth edge) on the dorsal flange on the 7–8th pectoral-fin rays of males ( Fig. 1C, D ), barbels not reaching orbit (vs. barbels reaching orbit), fewer predorsal scales (about 40 vs. 50–60), and smaller size (to 25.8 vs. 30.8 mm SL).

Description. Morphometric data in Table 4; small adult size (averaging 19.4 mm SL); body depth increasing from snout to nape, then decreasing to caudal peduncle ( Fig. 1B ); dorsal fin with 2 unbranched, 6 branched rays, last branched ray split to base; anal fin with 2 unbranched, 5 branched rays, last branched ray split to base; pectoral fin with 1 unbranched, 7 branched rays; pelvic fin with 1 unbranched, 6 branched rays; 16 caudal rays (7 branched, 1 unbranched in each lobe); caudal fin forked; dorsal-fin origin anterior to pelvicfin origin; in mature males 7–8th pectoral-fin rays with large (extending along> 75% of length of rays), dorsally projecting rounded rectangular flange with about 25 fine serrations and smaller, ventrally rounded flange ( Fig. 1C, D ); axial process in well-preserved specimens as small pocket of skin projecting from pectoral-fin base, not fused to rays; 30–46 predorsal scales (average about 40); no scales on top and side of head; anterior nostril on end of small outwardly projecting tube; suborbital bifid spine with anterior projection smaller than posterior; barbels: 2 rostral pairs, 1 maxillary pair at corner of mouth, medially split mandibular lobe forming 2 medially thickened mouth flaps; barbels small: first pair of rostral barbels not reaching anterior nostril, other pairs not reaching orbit; ventral mouth flaps usually without fringes.

Color in alcohol. Lepidocephalichthys zeppelini has pale yellow to white belly, background overlain with dark-brown marks on side, dorsum, head, and fins. Six–14 dark-brown blotches on side disconnected in females, connected by narrow stripe in males. Dark-brown chevron (<- shaped mark) at base of caudal fin points towards head, similar to that in L. furcatus ( Kottelat & Lim 1992) , but usually darker. Three to five predorsal and 3–6 postdorsal irregular dark blotches, chevrons, or bars on dorsum, with one at dorsal-fin base ( Fig. 1A ). Most specimens with small, inconspicuous dark spot on upper caudal-fin base spanning principal rays 4–7. Caudal, anal, and dorsal fins darkly reticulated. Dark stripe extends from snout, through eye, onto top of head, forming two dark spots on top of head where it terminates; otherwise, top of head with small dark-brown spots forming no pattern.

Sexual dimorphism. In addition to the modified pectoral fins and sexual dichromatism described above, L. zeppelini has other sexual dimorphisms characteristic of Lepidocephalichthys . Males have significantly (P <0.001, Student’s two-tailed, unpaired t-test assuming equal variance) larger pectoral fins ( Table 2) and pelvic fins ( Table 5) than females. Males are also significantly (P <0.001, Student’s two-tailed, unpaired t-test assuming equal variance) smaller than females: males average 18.1 mm SL and reach 21.7 mm SL whereas females average 19.9 mm SL and reach 25.8 mm SL.

Relationships. Clades containing seven individuals of L. zeppelini for cyt b ( Fig. 2A ), and four individuals for RAG1 ( Fig. 2B ), were resolved as a distinct lineage within Lepidocephalichthys with 100% support in all analyses. In the cyt b analysis ( Fig. 2A ), L. zeppelini grouped most closely with L. thermalis (Valenciennes) ; RAG1 sequences suggested a closer relationship between L. zeppelini and L. kranos Havird & Page ( Fig. 2B ). The average intraspecific divergence for L. zeppelini was 0.1% for cyt b and 0.2% for RAG1. The average interspecific divergence between L. zeppelini and L. thermalis was 22.0% for cyt b, and between L. zeppelini and L. kranos was 8.9% for RAG1.

Distribution and habitat. Lepidocephalichthys zeppelini is known from the Mekong drainage in Thailand and Vietnam ( Fig. 3 ) where it has been collected with L. hasselti and L. kranos . It has been found mainly in agricultural fields in small shallow pools ( Fig. 4 ). One juvenile was collected in a small sandy stream.

Previous collectors of L. zeppelini described its habitat as marshes or rice paddies. While collecting in Thailand in June at the beginning of the wet season, we originally targeted small streams, marshes, and flooded rice fields with little success, yielding only a few juveniles. However, when small ephemeral pools in otherwise dry agricultural fields were targeted, many adults were collected. At the type locality ( Fig. 4 ), pools less than 9 m 2 contained the majority of L. zeppelini collected. Lepidocephalichthys hasselti was also abundant in these pools, along with other common Southeast Asian freshwater fishes including species of Anabas , Puntius , Rasbora , Channa , and Hampala .

Etymology. The species name zeppelini is a reference to the 1968–1980 band Led Zeppelin. Use of the Gibson EDS-1275 double-neck guitar by Jimmy Page reminded us of the diagnostic double lamina circularis of this species. It is Latinized as a noun in the genitive singular.

Figures

FIGURE 1. Lepidocephalichthys zeppelini, new species, UF 174131 (holotype), 21.1 mm-SL male, Thailand, Ubon Ratchathani, Mun River (tributary of Mekong River), isolated pools in a rice field, Ubon Rajathanee University campus: (A) dorsal view, (B) lateral view, (C) lamina circularis on pectoral fin, (D) medial view of pectoral fin removed from UF 174130 (22.2 mm-SL male paratype) showing lamina circularis.

FIGURE 2. Phylogeny of species of Lepidocephalichthys based on Bayesian analysis of cyt b (A) and RAG1 (B). Clades of species are alternatively shaded. Since the parsimony analysis gave a very similar topology, support values for both analyses are presented at each node (numbers on left are posterior probabilities and numbers on right are bootstrap values). Asterisks indicate Bayesian support values of 0.95 or greater and parsimony support values of 0.90 or greater; single asterisks meet both criteria. Dashes indicate relationships were not supported in the parsimony analysis. Lepidocephalichthys zeppelini, n. sp. and L. kranos, recently described by Havird & Page (2010), are bolded and their support values are circled.

FIGURE 3. Distribution of Lepidocephalichthys zeppelini. Black dots represent localities for specimens examined; circle represents type locality.

FIGURE 4. Type locality of Lepidocephalichthys zeppelini. Individuals were in small ephemeral pools in otherwise dry agricultural fields. Most other specimens are from similar habitats.