Paedocypris carbunculus, Britz & Kottelat, 2008

Britz, Ralf & Kottelat, Maurice, 2008, Paedocypris Carbunculus, A New Species Of Miniature Fish From Borneo (Teleostei: Cypriniformes: Cyprinidae), Raffles Bulletin of Zoology 56 (2), pp. 415-422 : 417-420

Paedocypris carbunculus , new species

( Figs. 2–4 )

Material examined. – Holotype: MZB 10981, 9.7 mm SL, male,

immediate preanal area, then curving dorsally again up to posterior end of anal-fin base. From there dorsal and ventral contours almost parallel again, only slightly converging towards each other as caudal peduncle tapers posteriorly. Body laterally compressed. In dorsal view lateral contour tapering continuously from widest region of head just behind eye to end of caudal peduncle. Lateral head contour parallel in opercular area, then tapering towards snout.

Both sexes with short dorsal precaudal larval fin fold and long ventral precaudal larval finfold. Males with prepelvic pad. Females with persisting preanal larval fin fold.

Morphometric information based on 10 adult specimens (incl. holotype; 2 males, one female of CMK 19658; 4 females, 3 males of BMNH 2008.4.14.2–26). Head length 20–23 % standard length (SL), head depth 14–16 % SL, predorsal length 55–58% SL, preanal length 50-54 % SL, prepelvic length 35–39 % SL, caudal peduncle length 36–39 % SL, caudal peduncle depth 6–8 % SL, body depth 17–21 % SL, dorsal-fin height 17–20 % SL, anal-fin height 14–17 % SL, caudal-fin length 18–21 % SL, pelvic-fin length 7–10 % SL, pectoral-fin length 14–18 % SL, eye diameter 8–10 % SL. Fin ray counts based on above 10 specimens: Dorsal fin ii, 4, i (10 specimens), anal fin iii, 7, i (5), iii, 6, ii (3) or iii, 6, i (1), or iii, 8, i (1). Pectoral fin 6 (1) or 7 (9). Pelvic fin 5 (10) .

Colouration. – In 70% ethanol ( Figs. 3 , 4 ): Entire body whitish, only coloration being numerous chromatophores in specific patterns. Head dorsally with anterior and posterior head blotches, both larger and more conspicuous in male; both blotches consisting of contiguous chromatophores with brown periphery and dark brown to black center. Anterior head blotch in male extending from horizontal at anterior limit of eyes posteriorly to epiphyseal bar, roughly oval in shape with small median indentation at posterior rim. Posterior blotch in male extending from posterior edge of epiphyseal bar to posterior end of tectum synoticum, broad posteriorly with convex outlines, abruptly narrowing at anterior third, where outlines concave. Anterior head blotch in female restricted to small oval area at horizontal through middle of eyes. Posterior head blotch in female restricted to area between ear capsules, but with an anterior narrow extension reaching posterior edge of epiphyseal bar. In both sexes, area limited medially by tapering anterior end of posterior head blotches, anterolaterally by eye, and posterolaterally by ear capsules with a number of separated large and interspersed tiny (a fifth of diameter of large ones) chromatophores. This area separated posterolaterally by a pigmentless parallel space from a streak of pigment following anterior edge of otic capsule. Small and large chromatophores between anterior head blotch and eye. Rostral to anterior head blotch with numerous, dense, tiny and fewer more distantly spaced chromatophores arranged in an area following the curvature of the ethmoid region. Postotic pigment row extending from posterior third of posterior head blotch laterally and ventrally following posterior rim of ear capsule down to pectoralfin base. Lateral head region with irregularly distributed chromatophores on ear capsule, behind eye, on lachrymal area, and upper and lower jaw. Rows of chromatophores following curvature of opercle, subopercle, preopercle, and branchiostegal rays, latter three continuing first ventrally and then anteriorly. Ventral head region in addition with sparse chromatophores on hyoid and basihyal (= isthmus), and gular area.

Dorsally, posterior head blotch contiguous with middorsal stripe consisting of separated chromatophores arranged in three irregular, but recognizable rows with sparsely interspersed tiny chromatophores. Trunk with midlateral row of chromatophores from shoulder girdle to caudal-fin base. Head kidney pigment at angle formed by midlateral row and postotic row, extending down to pectoral-fin base. Swimbladder rows continuous and well developed confluent posteriorly with ventrolateral row. Anal-fin base row continuing posteriorly to caudal-fin base as larval fin fold row at base of fin fold, very close to but still slightly separated dorsally from ventrolateral row. Ventrolateral abdominal pigment well developed as numerous large and fewer tiny chromatophores. Chest blotch extending between cleithral symphysis and area slightly anterior to pelvic-fin base, developed as an elongate area of chromatophores of same kind as dorsal head blotches (irregular brownish periphery and dark brown to black centre) and a number of large chromatophores. Posterior and lateral to chest blotch with numerous tiny, but very few or no large chromatophores. Preanal pigmentation consisting of a number of large chromatophores forming an elongate blotch, separated from ventrolateral pigment by numerous tiny chromatophores. All fins transparent except for tiny chromatophores lining fin rays.

In life (fig. 2): Individuals mostly transparent with a reddish tinge on body, caused by numerous red chromatophores. Mature males with a bright red body in ventral half of abdominal and caudal area and with anterior and posterior head blotches glowing red.

Etymology. – The species name is derived from the Latin carbunculus , meaning the gemstone ruby and alludes to the ruby in live colouration. A noun in apposition.

Habitat. – The type locality is a small stream, 3–6 m wide and 0.5 to 2 m deep; the substrate ranges from sand to detritus and peat, with flowing blackwater. Perrin & Beyer (2008a) reported that in June 2005, the water conductivity was 20 µS/cm at 29°C and the pH 4.1. Paedocypris carbunculus was observed in areas with slow current, near the surface, usually forming small shoals (estimated to up to 100–200 individuals), most abundant near or under overhanging structures or submerged vegetation near the surface (branches, leaves, etc.). The shore vegetation was abundant and dense (secondary forest or riparian corridor) and under there was very little light penetration. About 17 other species have been collected at the type locality, with Hemirhamphodon phaiosoma sharing about the same habitat as P. carbunculus ; Perrin & Beyer (2008a) also mention the presence of H. tengah .

Biology. – Paedocypris carbunculus has been kept in the aquarium and bred over at least two generations (Perrin & Beyer, 2008a). The following account is based on Perrin & Beyer’s (2008a) report, supplemented by information, photographs and video-clips provided by O. Perrin. Spawning starts in the early morning hours. Males flash their glowing red head blotches and attract females to the spawning site under leaves of water plants, where eggs are deposited. Once the male has been successful in attracting a female, the actual spawning act is extremely fast and impossible to observe in detail as it lasts less than one second. Photographs, however, reveal that both partners turn into an upside down position with their bellies directed towards the plant, then one or a few eggs are released and adhere to the leaf ( Fig. 7 ). Before and between successful spawnings males can be seen remaining upside down and close to the leaf with their pelvic fins moving very fast back and forth over its surface. Among the pictures of the spawning act published by the authors is one that shows the male in an almost circular, close embrace with the female, which has its head, abdomen, and tail bent away from the leaf so that the genital opening is very close to the substrate ( Fig. 7c ). Other photographs illustrate both partners in a parallel upside down position under the leaf ( Fig. 7b ). Photographs of the male immediately before the actual spawning act also show its genital opening close to the substrate and its anterior anal-fin rays inclined strongly anteriorly. One photograph depicts a male with the prepelvic pad, the pelvic fins and the tip of the anal fin in close contact with previously laid eggs ( Fig. 7d ).

There is no parental care after egg deposition and eggs hatch after 36 hours. Hatched larvae remain attached and motionless until after a few hours the yolk sac is resorbed. For the next few weeks they swim very close to the water surface and their growth is surprisingly slow. In captivity, they require more than 6 months to reach maturity.

Figures

Fig. 2. Live specimen of Paedocypris carbunculus, not preserved, male above, female below (Photos: Heok Hui Tan).

Fig. 3. Paedocypris carbunculus, new species, holotype, male, MZB 10981, 9.7 mm, and paratype, female, CMK 19658, 10.8 mm; Indonesia: Kalimantan Tengah, Pangkalan Bun.

Fig. 4. Paedocypris carbunculus, new species, holotype (left), male, MZB 10981, 9.7 mm, and paratype (right), female, CMK 19658, 10.8 mm; head and anterior trunk in dorsal (above) and ventral view (below) to illustrate pigmentation pattern.

Fig. 7. Paedocypris carbunculus, spawning behaviour: a, male has attracted a female; b, male and female in parallel posture during egg deposition; c, both in spawning embrace; d, male in contact with eggs via pelvic fins and keratinized pad (Photos: Oliver Perrin).