Tetraodon palustris, Saenjundaeng, Pasakorn, Vidthayanon, Chavalit & Grudpun, Chaiwut, 2013

Saenjundaeng, Pasakorn, Vidthayanon, Chavalit & Grudpun, Chaiwut, 2013, Tetraodon palustris, a new freshwater pufferfish (Tetraodontiformes: Tetraodontidae) from the Mekong Basin of Thailand, Zootaxa 3686 (1), pp. 77-84 : 78-82

Tetraodon palustris sp. nov.

( Figs. 1–2 )

Holotype. Mekong basin, Thailand: KUMF 8834, holotype, 72.1 mm SL, Nongkomkoh Swamp, Amphoe Mueang, Nong Khai Province, 7 September 2011, P. Saenjundaeng.

Paratypes. Mekong basin, Thailand: KUMF 8835, 6, 54.9–76.9 mm SL, Nongkomkoh Swamp, Amphoe Mueang, Nong Khai Province, 7 September 2011, P. Saenjundaeng; NIFI 0 0 624, 1, 94.6 mm SL, Amphoe Tha Bo, Nong Khai Province, 6 June 1977, J. Ratanathavee; NIFI 0 0 513, 1, 66.8 mm SL, Nong Khai market, Nong Khai Province, 8 February 1985, S. Sontirat; NIFI 0 0 630, 51.4 mm SL, Amphoe Tha Bo, Nong Khai Province, 3 June 1987, S. Soontornsathit; KUMF 8836, 8, 78.2–91.8 mm SL, Nongkon Swamp, Amphoe Rattanawapi, Nong Khai Province, 25 September 2011, P. Saenjundaeng and R. Mapanao; KUMF 8837, 14, 73.2–84.8 mm SL, Kud-Thing Marsh, Ban Don Ho, Amphoe Mueang, Bung Kan Province, 18 March 2012, P. Saenjundaeng; KUMF 8838, 10, 54.3–70.2 mm SL, Huai Luang Reservoir, Udon Thani Province, 28 December 2011, P. Saenjundaeng; KUMF 8839, 10, 55.8–68.1 mm SL, Huai Luang Reservoir, Udon Thani Province, 29 December 2011, P. Saenjundaeng; KUMF 8840, 13, 65.2–81.2 mm SL, Ban Maet, Amphoe Sang Khom, Udon Thani Province, 13 March 2012, P. Saenjundaeng; NIFI 0 3425, 4, 37.2–45.9 mm SL, Nong Han Reservoir, Sakon Nakhon Province, 25–28 July 1985, S. Lamlerddecha; NIFI 0 3628, 1, 40.6 mm SL, Nong Han Reservoir, Sakon Nakhon Province, 25–28 July 1985, S. Lamlerddecha.

Diagnosis. Tetraodon palustris differs from T. cochinchinensis and T. fangi in having no ocellus on the flank and spinules on the dorsum from the interorbital region to the end of the dorsal-fin base.

Description. Body stout, dorsal profile from anterior-most part of snout to end of dorsal-fin base convex. In %HL: mouth width 26.7–32.2; short, blunt snout, snout length 39.1–44.6; eye high on head, protruding laterally, round, diameter 19.2–25.0; interorbital distance 54.2–66.9; internasal distance 27.4–33.4; head depth at preorbital 47.8–60.1, width at preorbital 45.1–55.1, depth at postorbital 65.8–77.3, width at postorbital 74.1–85.3, depth at nape 74.3–86.9, width at nape 81.0–93.9. In %SL: head length 39.0–43.1, interpectoral fin distance 27.3–31.2, prepectoral-fin length 41.0–45.8, predorsal-fin length 72.4–77.8, preanal-fin length 77.1–82.6, pectoral-fin base length 9.4–11.4, dorsal-fin base length 8.5–10.8, anal-fin base length 5.8–7.4, body depth at middle of dorsal-fin base 17.4–22.1, body width at middle of dorsal-fin base 16.8–21.6, caudal-peduncle length 13.3–17.1, caudalpeduncle depth 10.6–14.1, caudal-peduncle width 12.3–16.3. Area with spinules: dorsally from interorbital region to end of dorsal-fin base, laterally from nasal organ to between end of dorsal-fin base to origin of anal-fin base, ventrally from chin to anus. Fin-ray counts: pectoral ii,19–22; dorsal ii–iii,10–12; anal i–ii,8–10; caudal ii,6,ii.

Colour. Male, live specimen ( Fig. 1 A–C). The dorsolateral surface of body has a dark greenish black background with numerous round black spots. The belly is gray-black with a white reticulated network. Preserved specimens from Ban Maet, Amphoe Sang Khom, Udon Thani Province, exhibit a yellow and greenish-black background dorsolaterally ( Fig. 2 A–C). On the female, the dorsolateral surface of the body has a yellow or light greenish-black background with numerous round black spots. The belly has a white background with many small dark spots ( Fig. 2 D–F). There are several large dark spots on the lateral surface of the body in male and female specimens. Adult specimens of T. palustris have no ocellus on the flank while small juvenile specimens show only one ocellated spot with a red center. This ocellus changes to a large round black spot in the adult. The eye is orange to red. Pectoral, dorsal and anal fins are translucent greenish while the caudal fin is opaque and greenish-black.

Geographic distribution and ecological note. Tetraodon palustris is known from the middle Mekong basin in Thailand. It lives in marshes and swamps with clear and stagnant water in places with many aquatic plants. In Kud Thing Marsh, it occurs with T. suvattii and ca. 17 other fish species; i.e., Clupeichthys aesarnensis , Rasbora trilineata , Amblypharyngodon chulabhornae , Puntius brevis , Hampala dispar , Osteochilus vittatus , Oryzias mekongensis , Parambassis siamensis , Mystus mysticetus , Clarias macrocephalus , Brachygobius mekongensis , Neodontobutis aurarmus , Doryichthys contiguus , Indostomus spinosus , Nandus oxyrhynchus , Pristolepis fasciata , and Trichopodus trichopterus . Eight live specimens of T. palustris from Kud Thing Marsh were kept in an aquarium to study their behavior. They spent much of the time hidden among roots and in dense clumps of submerged plants. The diet of T. palustris in captivity was primarily juvenile fishes, including Nile Tilapia Oreochromis niloticus , and the cyprinids, Barbonymus gonionotus , Cirrhinus siamensis and Hypophthalmichthys molitrix .

Etymology. The Latin word, palustris , means of the marsh or swamp, referring to the main habitats of this new species, which lives in marshlands, swamps and floodplains.

Figures

FIGURE 1. Fresh specimen of Tetraodon palustris, KUMF 8834, holotype, male 72.1 mm SL, Nongkomkoh Swamp, Amphoe Mueang, Nong Khai Province, Thailand: A) lateral, B) dorsal, and C) ventral views.

FIGURE 2. Preserved specimens of Tetraodon palustris, KUMF 8840, Ban Maet, Amphoe Sang Khom, Udon Thani Province: A-C) male 78.9 mm SL, D-F) female 77.2 mm SL.