Betta mahachaiensis, Kowasupat, Chanon, Panijpan, Bhinyo, Ruenwongsa, Pintip & Sriwattanarothai, Namkang, 2012

Kowasupat, Chanon, Panijpan, Bhinyo, Ruenwongsa, Pintip & Sriwattanarothai, Namkang, 2012, Betta mahachaiensis, a new species of bubble-nesting fighting fish (Teleostei: Osphronemidae) from Samut Sakhon Province, Thailand, Zootaxa 3522, pp. 49-60 : 50-57

Betta mahachaiensis , new species

Pla Kad Pa Mahachai

( Figures 1–6 )

Holotype: THNHM-F- 01630 (37.41 mm SL), Thailand, Samut Sakhon province, Muang district, Tha Sai subdistrict , behind the Pattarachai food factory (13° 34' N, 100° 15' E); coll. C. Kowasupat et al., 30 Apr. 2011.

Paratypes: THNHM-F- 01617 , 12 ex., same locality as holotype; coll. N. Sriwattanarothai et al., 10 Nov. 2008.— THNHM-F- 01622 , 2 ex., same locality as holotype; coll. C. Kowasupat et al., 17 Dec. 2009.— THNHM-F- 0 1623 , 3 ex., same locality as holotype; coll. C. Kowasupat et al., 30 Apr. 2011.— THNHM-F- 01821 , 3 ex., same locality as holotype; coll. C. Kowasupat et al., 2 Sep. 2012.— THNHM-F- 01616 , 1 ex., Thailand, Samut Sakhon province, Muang district, Tha Sai subdistrict , Tong Tham Mikaram temple (13° 34' N, 100° 15' E); coll. P. Suadech et al., 10 Nov. 2008.— THNHM-F- 01822 , 3 ex., Thailand, Samut Sakhon province, Muang district, Tha Sai subdistrict , beside the Thai Prasit Textile factory (13° 34' N, 100° 16' E); coll. C. Kowasupat, 2 Sep. 2012.— THNHM-F- 01632 , 5 ex., Thailand, Samut Sakhon province, Muang district, Tha Sai subdistrict , inside Mahachai Villa housing estate (13° 34' N, 100° 15' E); coll. C. Kowasupat et al., 30 Apr. 2011.— THNHM-F- 0 1633, 3 ex., Thailand, Samut Sakhon province, Muang district, Tha Sai subdistrict , across the canal from Mahachai Villa housing estate (13° 34' N, 100° 15' E); coll. T. Jeenthong et al., 30 Apr. 2011.— THNHM-F- 01621 , 1 ex., Thailand, Samut Sakhon province, Muang district, Chai Mongkhon subdistrict, the road to Nuam Ka Non temple (13° 33' N, 100° 11' E); coll. B. Panijpan et al., 17 Dec. 2009.— THNHM-F- 01661 , 1 ex., Thailand, Samut Sakhon province, Muang district, Chai Mongkhon subdistrict, Nuam Ka Non temple (13° 33' N, 100° 11' E); coll. T. Jeenthong et al., 16 May. 2011.— THNHM-F- 01662 , 1 ex., Thailand, Samut Sakhon province, Muang district, Chai Mongkhon subdistrict , Nuam Ka Non temple (13° 33' N, 100° 11' E); coll. S. Petchjeed, 16 May. 2011.— THNHM-F- 01658 , 3 ex., Thailand, Samut Sakhon province, Muang district, Chai Mongkhon subdistrict , Bang Koi temple (13° 31' N, 100° 10' E); coll. B. Panijpan et al., 16 May. 2011.— THNHM-F- 01659 , 2 ex., Thailand, Samut Sakhon province, Muang district, Chai Mongkhon subdistrict , Pak Bo temple (13° 33' N, 100° 11' E); coll. B. Panijpan et al., 16 May. 2011.— THNHM-F- 01660 , 2 ex., Thailand, Samut Sakhon province, Muang district, Chai Mongkhon subdistrict , Nuam Ka Non temple (13° 33' N, 100° 11' E); coll. P. Ruenwongsa et al., 16 May. 2011.— THNHM-F- 01657 , 5 ex., Thailand, Samut Sakhon province, Muang district, Ban Bo subdistrict , 100 m from Ta Satit Toonklao bridge (13° 31' N, 100° 11' E); coll. C. Kowasupat et al., 29 May. 2011.— THNHM-F- 0 1655 , 3 ex., Thailand, Samut Sakhon province, Muang district, Bang Krachao subdistrict , Wisut Taram temple (13° 31' N, 100° 12' E); coll. C. Kowasupat et al., 29 May. 2011.— THNHM-F- 01656 , 5 ex., Thailand, Samut Sakhon province, Muang district, Bang Krachao subdistrict , Sri Wanaram temple (13° 30' N, 100° 31' E); coll. C. Kowasupat et al., 29 May. 2011.— THNHM-F- 01611 , 17 ex., Thailand, Samut Sakhon province, Muang district, Maha Chai subdistrict , Area 1 (13° 33' N, 100° 16' E); coll. P. Suadech et al., 7 Aug. 2008.— THNHM-F- 01612 , 2 ex., Thailand, Samut Sakhon province, Muang district, Maha Chai subdistrict , Area 2 (13° 33' N, 100° 16' E); coll. P. Suadech et al., 25 Jul. 2008.— THNHM-F- 01634 , 4 ex., Thailand, Samut Sakhon province, Muang district, Khok Kham subdistrict , along the railway opposite the Kaem Ling project (13° 33' N, 100° 18' E); coll. C. Kowasupat et al., 30 Apr. 2011.— THNHM-F- 01629 , 2 ex., Thailand, Samut Sakhon province, Muang district, Khok Kham subdistrict , near Sophon Naram temple (13° 34' N, 100° 18' E); coll. T. Jeenthong et al., 30 Apr. 2011.— THNHM- F- 01635 , 4 ex., Thailand, Samut Sakhon province, Muang district, Khok Kham subdistrict , Sophon Naram temple (13° 33' N, 100° 18' E); coll. S. Kruttha & B. Puangmalai, 30 Apr. 2011.— THNHM-F- 01652 , 2 ex., Thailand, Samut Sakhon province, Muang district, Khok Kham subdistrict , Khom village (13° 34' N, 100° 18' E); coll. S. Petchjeed, 1 May. 2011.— THNHM-F- 01653 , 1 ex., Thailand, Samut Sakhon province, Muang district, Khok Kham subdistrict , Ban Khom school (13° 33' N, 100° 18' E); coll. S. Petchjeed, 1 May. 2011.— THNHM-F- 01615 , 1 ex., Thailand, Samut Sakhon province, Muang district, Na Di subdistrict , Ba Lee (13° 35' N, 100° 17' E); coll. S. Suadech et al., 10 Nov. 2008.— THNHM-F- 01623 , 1 ex., Thailand, Samut Sakhon province, Muang district, Na Di subdistrict , behind Index factory (13° 34' N, 100° 17' E); coll. A. Rungreungwuttikul et al., 26 Feb. 2011.— THNHM-F- 01624 , 1 ex., Thailand, Samut Sakhon province, Muang district, Na Di subdistrict , behind Index factory (13° 34' N, 100° 17' E); coll. V. Pinkaew, 5 Mar. 2011.— THNHM-F- 01666 , 1 ex., Thailand, Samut Sakhon province, Muang district, Na Di subdistrict , 500 m from Makham Wan restaurant (13° 35' N, 100° 17' E); coll. S. Petchjeed, 26 May. 2011.— THNHM-F- 01626 , 1 ex., Thailand, Samut Sakhon province, Muang district, Ban Ko subdistrict , Bang Pla (13° 34' N, 100° 13' E); coll. A. Rungreungwuttikul et al., 12 Dec. 2010.— THNHM- F- 01628 , 3 ex., Thailand, Samut Sakhon province, Muang district, Khok Krabue subdistrict , beside SL plastic factory (13° 34' N, 100° 20' E); coll. C. Kowasupat et al., 30 Apr. 2011.— THNHM-F- 01627 , 1 ex., Thailand, Samut Sakhon province, Muang district, Phan Thai Norasing subdistrict , about 300 m from Phan Thai Norasing shrine (13° 31' N, 100° 22' E); coll. A. Rungreungwuttikul et al., 12 Dec. 2010.— THNHM-F- 01625 , 1 ex., Thailand, Samut Sakhon province, Ban Phaeo district (13° 35' N, 100° 6' E); coll. A. Rungreungwuttikul et al., 14 Nov. 2010.— THNHM-F- 01667 , 2 ex., Thailand, Samut Sakhon province, Ban Phaeo district (13° 35' N, 100° 6' E); coll. P. Ruenwongsa et al., 2 Sep. 2011.— THNHM-F- 01664 , 5 ex., Thailand, Bangkok province, Bang Khun Thian district, Samae Dam subdistrict (13° 36' N, 100° 24' E); coll. S. Kruttha et al., 14 May. 2011.— THNHM-F- 0 1665 , 1 ex., Thailand, Bangkok province, Bang Khun Thian district, Samae Dam subdistrict , Bang Kradi 43 (13° 33' N, 100° 11' E); coll. C. Sibsam, 1 Jun. 2010.— THNHM-F- 01666 , 1 ex., Thailand, Bangkok province, Bang Khun Thian district, Samae Dam subdistrict , Bang Kradi 43 (13° 33' N, 100° 11' E); coll. P. Ruenwongsa et al., 29 May. 2011.

Diagnosis: Betta mahachaiensis is distinguishable from other congeners in the B. splendens group by the combination of the following characters: an iridescent green to bluish-green appearance on the brown-to-black body background; two parallel iridescent green to bluish-green vertical bars on opercle; brown-to-black opercular membrane without red streaks or patches; dorsal, caudal, and anal fin rays brown to black contrasting with iridescent green or bluish-green interradial membranes; dorsal fin with at least its proximal two-thirds having transverse black bars; absence of dark transverse bars on caudal fin, small black rounded marks flanking the internal rays on interradial membranes; pelvic fin brown to black with iridescent green/bluish-green front margin and white tip; head length 24.9–31.2% SL; postdorsal length 17.1–25.2% SL; length of dorsal fin base 12.2–19.3% SL; pelvic fin length 21.2–49.6%; pectoral fin length 15.4–21.3% SL; orbit diameter 22.8–29.7% SL.

Betta mahachaiensis

SPECIES Betta splendens Betta smaragdina

Holotype Paratype

Number of specimens 1 40 40 40

S.D. S.D. S.D.

Min.–Max. Mean Min.–Max. Mean Min.–Max. Mean

(±) (±) (±) * Nonnormal distribution by using the Shapiro-Wilk test for normality (α=0.05)

a B. mahachaiensis is significantly different from B. splendens (α=0.05, Bonferroni-adjusted) b B. mahachaiensis is significantly different from B. smaragdina (α=0.05, Bonferroni-adjusted) Description: General body shape and appearance illustrated in Figs. 2–3 . Head small, short (head length 24.9–31.2 % SL), eyes large (orbital diameter 22.8–29.7 % SL); adult males with convex hump at posterior of head, immediately behind eye; body slender (body depth 21.6–31.4 % SL); opercles parallel when head viewed dorsally; dorsal fin positioned after mid-body (predorsal length 59.1–68.2 % SL); caudal fin posterior margin rounded to medially pointed; dorsal fin distal margin rounded; pelvic fins falcate; anal fin pointed. Meristic and morphometric data are summarized in Tables 1 and 2. Maximum size: 43.7 mm SL (THNHM-F-01623).

Coloration: See Fig. 2 for coloration in life. Male with dark-brown to black head, with iridescent green to bluish-green scales. Opercles with two parallel iridescent green to bluish-green vertical bars, opercular membrane brown to black, eyes with iridescent green to bluish-green patches at bottom and posterior regions. Body dark brown to black with iridescent green to bluish-green scales arranged in regular rows, with a similar iridescent area on each scale. Dorsal, caudal, and anal fin rays brown to black, contrasting with iridescent green to bluish-green interradial membranes; dorsal fin with at least proximal two-thirds having black transverse bars; small black rounded marks flanking internal rays on interradial membranes in most specimens (60 out of total 65); pelvic fin brown to black, with iridescent green to bluish-green front margin, white tip; pectoral fins hyaline. Female less colourful (see Fig. 3 ): head and body yellowish to light-brown with iridescent green to bluish-green scales; opercles pale gold with two faint iridescent green to bluish-green bars; throat with ‘chin-bar’. Body with distinct upper central stripe nearly parallel to central stripe, at level of eye; caudal-peduncle black spot present. Dorsal, caudal, anal, and pelvic fin rays yellowish on faint iridescent green to bluish-green interradial membranes. Other characters similar to male.

Betta mahachaiensis

SPECIES Betta splendens Betta smaragdina

Holotype Paratype

Number of specimens 1 40 40 40

Min.–Max. Mode Min.–Max. Mode Min.–Max. Mode Comparative notes: Betta mahachaiensis is distinguishable from other congeners in B. splendens group by having the opercle with two parallel iridescent green to bluish-green vertical bars (vs. parallel red vertical bars in B. splendens and green iridescent scales in B. smaragdina and B. stiktos ) (see Fig. 4 ); brown-to-black opercular membrane without red streaks or patches (vs. presence of red streaks in B. splendens , B. imbellis , B. smaragdina , and B. stiktos ); caudal fin rays brown to black, contrasting with iridescent green to bluish-green interradial membranes (vs. presence of distal red crescent with a thin black edge in B. splendens and B. imbellis ); absence of dark transverse bars on caudal fin (vs. presence in B. stiktos ); anal fin rays brown to black with iridescent green to bluish-green on interradial membranes (vs. distal half of posterior anal fin rays red with a small red patch at distal tip in B. splendens and B. imbellis ); pelvic fin brown to black with iridescent green to bluish-green front margin and white tip (vs. black and red from proximal pelvic fin base to the white tip in B. splendens and B. imbellis ); smaller head length than B. splendens and B. smaragdina (24.9–31.2% SL vs. 26.6–33.1); smaller postdorsal length than B. splendens and B. smaragdina (17.1–25.2% SL vs. 19.1–27.6); smaller length of dorsal fin base than B. smaragdina (12.2–19.3% SL vs. 14.6–19.9); smaller pelvic fin length than B. smaragdina (21.2–49.6% SL vs. 28.3–25.2); smaller pectoral fin length than B. smaragdina (15.4–21.3% SL vs. 15.3–24.4); smaller orbit diameter than B. smaragdina (22.8–29.7% SL vs. 23.0–31.4).

Distribution: Based on our survey of fighting fish during 2007–2012, the wild B. mahachaiensis was found only in two provinces in Thailand: 28 catch sites in Samut Sakhon Province and 2 sites in western Bangkok bordering Samut Sakhon Province ( Fig. 5 ). The catch sites were in Samut Sakhon Province's Muang district encompassing Mahachai and other subdistricts, viz. Tha Sai, Na Di, Khok Kham, and nearby districts including Ban Phaeo. We have not been able to collect any wild B. mahachaiensis in Samut Prakan and Samut Songkhram, as cited in earlier reports (see Monvises et al., 2009). Nevertheless people in the villages of this area claim to have caught specimens in Samut Songkhram Province adjacent to Samut Sakhon.

Reproductive behaviour: During spawning, the females, while upside-down or nearly so, have been observed to cradle some of the eggs emerging from the vent of the ovipositor with the pelvic and pectoral fins before the falling eggs are picked up by the mate. As with other members of the B. splendens group, the female fish also help in picking up eggs and placing them in the bubble-nest.

Field Notes: Betta mahachaiensis lives in brackish waters, some quite heavily polluted; pH at catch sites 6.87–7.80, salinity 1.1–10.6 ppt. The species was found in nipa palm ( Nypa fruticans ) swamps, especially, in the water-holding phytotelma of the palm bract, which the pair use for bubble-nest building, courtship, and hatching of fry (see Fig. 6 ). Some syntopic fish species, although not found in the bract's watery pocket, are Trichopsis vittata , Trichopodus trichopterus , Anabas testudineus , Aplocheilus panchax , Oryzias javanicus , Dermogenys siamensis , Channa striata and Boraras urophthalmoides .

Etymology: The name Betta mahachaiensis is derived from its common Thai name for a subdistrict of Samut Sakhon Province, viz. Maha Chai, the first publicised collecting site.

Remarks: B. mahachaiensis has been found only in Thailand, while other members of B. splendens group occur also in three neigbouring countries, namely Laos, Cambodia, and Malaysia. Additional support for B. mahachaiensis as a distinct species comes from our nuclear DNA sequencing of wild-caught and tank-bred specimens. Our previous results from mitochondrial DNA barcoding of cytochrome c oxidase I (COI) (gene bank accession no. GQ911877 -904) and 16S rRNA ( GQ912150 -85) ( Sriwattanarothai et al. 2010) additional COI barcoding sequence ( JQ818643 -64, JQ818675 -90, and JQ818693 ) and nuclear gene (internal transcribed spacer 1 or ITS1) ( JQ818556 -63 and JQ818568 -74) support the taxonomic status of B. mahachaiensis as an independent lineage. The Kimura 2-parameter (K2P) distances estimated from COI between B. mahachaiensis and B. splendens is 0.110 (about 11%) and that between B. mahachaiensis and B. smaragdina is 0.147 (about 14%) (in preparation). The accession numbers (www.ncbi.nlm.nih.gov) of the holotype B. mahachaiensis are JQ818652 (COI) and JQ818561 (ITS1).

One fish breeder (Suwit Suadech) of long standing has bred B. mahachaiensis for more than 10 years and many more generations and this fish have always bred true, i.e., no occasional morphologically B. splendens -like fish or B. smaragdina -like ones have ever emerged. Our DNA barcoding results of all B. mahachaiensis from his farm are unique to the B. mahachaiensis with none having COI barcoding characteristics of B. splendens or other fish in the B. splendens group. We are confident therefore, that B. mahachaiensis is neither of hybrid origin nor a cultivated form. On the contrary, some fish bought from the Chatuchak market have been found to be hybrids with DNA barcoding characters of B. splendens despite their general appearance being very much like that of B. mahachaiensis .

The new DNA sequences of B. splendens , B. imbellis , and B. smaragdina cited above not included in Sriwatanarothai et al. 2010 are: JQ818724 -8, JQ818784 -5, JQ818797 -806 for COI gene of B. splendens ; JQ818637 -40, JQ818608 -9 for ITS1 gene of B. splendens ; JQ818776 -81, JQ818783 , JQ818786 -96 for COI gene of B. imbellis ; JQ818594 -605, JQ818607 , JQ818610 -19 for ITS 1 gene of B. imbellis ; JQ818744 -9, JQ818753 -75 for COI gene of B. smaragdina ; and JQ818581 -3, JQ818588 -93 for ITS1 gene of B. smaragdina .

Figures

FIGURE 1. Betta mahachaiensis, THNHM-F- 01630, male, holotype, 37.4 mm SL, GenBank Accession Numbers: JQ 818561 (COI), JQ 818652 (ITS 1).

FIGURE 2. Betta mahachaiensis: (a) schematic drawing of a specimen, an adult male, paratype, THNHM-F- 01622, 35.2 mm SL; (b) photograph of live adult male displaying aggression, paratype, THNHM-F- 01623, 36.7 mm SL (note that gill covers are open, displaying the red gills, which are not the red bars on the opercle).

FIGURE 3. Betta mahachaiensis: (a) live male (acclimatized), paratype, THNHM-F- 01658, 35.5 mm SL; (b) live female (acclimatized), paratype, THNHM-F- 01554, 27.1 mm SL.

FIGURE 4. Close-ups of heads & opercle patterns of live males: (a) Betta splendens, THNHM-F- 01703; (b) Betta imbellis, THNHM-F- 01560; (c) Betta mahachaiensis, THNHM-F- 01632; (d) Betta smaragdina, THNHM-F- 01778; (e) Betta stiktos, THNHM-F- 01824.

FIGURE 5. (a) Map of Thailand showing Betta mahachaiensis catch sites (encompassed by the small rectangle in the middle) in the central part of Thailand (C-Central, N-North, S-South, W-West, E-East, and NE-Northeast); (b) Catch (stars) of Betta mahachaiensis between years 2007 and 2012, twenty-eight sites in Samut Sakhon province and two sites in west of Bangkok.

FIGURE 6. Habitat of Betta mahachaiensis in Samut Sakhon province, Thailand: (a) Nipa palm forest behind a food factory (Type Locality) (30 Apr. 2011); (b) Water held in the pocket phytotelma of the nipa palm bract as spawning space and the fish (THNHM-F- 01632) caught from it (30 Apr. 2011); (c) The fish (THNHM-F- 01655) and bubble nest in a pocket of a nipa palm bract (29 May 2011).