Barbodes pyrpholeos, Hui & Husana, 2021

Hui, Tan Heok & Husana, Daniel Edison M., 2021, Barbodes pyrpholeos, new species, the first cave-dwelling cyprinid fish in the Philippines, with redescription of B. montanoi (Teleostei: Cyprinidae), Raffles Bulletin of Zoology 69, pp. 309-323 : 310-315

Barbodes pyrpholeos , new species

( Figs. 1–8 )

Unidentified cyprinid fish – Husana, 2020: 216.

Material examined. Holotype — PNM 15649, 104.1 mm SL; Philippines: Mindanao, Agusan drainage; Ugnop Cave system; coll. D. E. Husana, 14 May 2014.

Paratypes — PNM 15650, 2 ex. , ZRC 61230, 3 ex., 69.6–93.1 mm SL; same locality data as holotype . — PNM 15651, 3 ex. , ZRC 61231, 3 ex., 68.2–103.4 mm SL; Philippines: Mindanao , Agusan drainage; Ugnop Cave system; coll. Prosperidad Mountaineering Club, 1 May 2012 . — ZRC 61232, 2 ex., 59.7–76.1 mm SL; Philippines: Mindanao , Agusan drainage; Ugnop Cave system; coll. D. E. Husana and local residents, 14 May 2014 .

Diagnosis. Barbodes pyrpholeos can be differentiated from all congeners by the following unique combination of characters: body with little brown pigment, appearing white or pinkish in life; unpaired fins with posterior half bright orangey-red in life, anterior half of unpaired fins and paired fins hyaline; eyes present and pigmented, possibly still functional. All other congeners (except the cave-dwelling B. microps ) having body with black blotches, bars, stripes, dots, and triangular markings; body and fins appear pigmentless in B. microps (information on colours in life not available). Barbodes pyrpholeos can be further differentiated from B. microps (some data obtained from Haryono, 2006) in having the following characters: eye present, though variable in size (based on available material only) vs. eye absent or represented by a small, possibly non-functional eye in some individuals of B. microps ; more dorsal-fin rays (8–9½, vs. 8); greater mean head length (32.3% SL, vs. 30.8%); lower mean predorsal length (55.1% SL, vs. 57.5%); lower mean body depth at anus (20.6% SL, vs. 36.5%); lower mean caudal peduncle depth (12.4% SL, vs. 14.7%); larger eye diameter (14.9–22.3, mean 17.3% HL, vs. 10.2–17.9, mean 14.9, when present).

From the geographically close congener Barbodes montanoi , the new species can be further distinguished by having a smaller eye (eye diameter 14.9–22.3% HL, vs. 21.9–29.4%), longer head (head length 30.7–34.1% SL, vs. 27.4–29.5%), slimmer body (body depth 19.1–22.2% SL, vs. 23.6–25.5%), slimmer caudal peduncle (caudal peduncle depth 11.6–12.9% SL, vs. 13.8–15.3%); last unbranched dorsal-fin ray spinous, but without serrations (see Fig. 8 ; vs. serrations present on last unbranched dorsal-fin ray); lateral series scales 23–25 (mode 23) (vs. 24–27, mode 24); predorsal scales 8–9 (mode 9) (vs. 8).

Description. See Figs. 1–7 for general impression, and Table 1 for meristic and morphometric data.

Body slim, deepest at dorsal-fin origin (27.9–31.7% SL), tapering to its narrowest at caudal peduncle (11.6–12.9% SL). Head blunt (head depth 56.3–68.5% HL, head width 54.1–63.9% HL), relatively long about ⅓ of standard length (head length 30.7–34.1% SL). Mouth sub-terminal, two pairs of maxillary barbels, barbels longer than eye diameter (up to three times), posterior pair longer than anterior, reaching past eye posterior margin. Eye relatively small (eye diameter 14.9–22.3% HL). Mouth large, gape height 9.0–15.1% SL, 26.6–43.3% HL; mouth width 9.2–15.1% SL, 29.8–46.9% HL. Dorsal-fin origin and pelvic-fin origin at roughly midbody (predorsal-fin length 51.2–56.7% SL; pre-pelvic fin length 53.4–61.9% SL), anal-fin origin at ¾ length of body (preanal-fin length 72.3–79.2% SL). Dorsal and anal fins triangular in shape, with a smooth and straight anterior margin, straight posterior margin. Caudal fin symmetrically forked (upper caudal-fin lobe length 25.5–33.3% SL; lower caudal-fin lobe length 25.5–33.0% SL). Pelvic fins triangular-shaped with straight margins, pectoral fin rounded. Lateral series with 23–25 scales (mode 23), 8–9 predorsal scales (mode 9), 4½.1.2½–3½ transverse scales, 11–12 circumpeduncular scales (mode 11), 4½ scales between lateral series and pelvic-fin origin. Vertebral count 17–18 + 14–15 = 32 (mode = 32; n = 8).

Live colouration. See Figs. 1–3 . Head and rest of body white or pinkish, with some body scales silvery. Eyes pigmented. Posterior half of unpaired fins orange-red, anterior half hyaline. Paired fins hyaline; posterior margin of pelvic fin with slight orange tint (observations based on photographs of 1–2 freshly caught specimens).

Preserved colouration. See Figs. 4–7 . Head and rest of body cream, with yellowish overtone. Dorsum of head and anterior part of body with extremely faint light brown pigment, most obvious around posterior margin of dorsal scales and forming weak reticulate pattern. An extremely faint light brown rounded blotch on caudal peduncle anterior to caudal-fin base. All fins hyaline.

Distribution. Known only from karstic cave systems in Mindanao Island, the Philippines.

Field notes. See Larson & Husana (2018: 98, fig. 1) and Husana (2020) for view of the habitat and syntopic species. Barbodes pyrpholeos was originally discovered by Arnel Pasilan (Prosperidad Mountaineering Club) during their earlier exploration, and brought to the attention of the second author.

Etymology. The species name is a combination of the Greek words pyr, meaning fire, and pholeos, meaning cave, in reference to the fiery red fins of this cave-dwelling species. Used as a noun in apposition.

Remarks. To date only three species of cave fish are recorded in the Philippines, viz. Caecogobius crypthophthalmus Berti & Ercolini, 1991 , Caecogobius personatus Larson & Husana, 2018 , and this present new species, Barbodes pyrpholeos . The majority of Philippine aquatic cave species recorded so far are invertebrates. Husana (2020) reviewed various species of cavernicolous crabs in the Philippine archipelago, belonging to the families Gecarcinucidae , Gecarcinidae , Hymenosomatidae , Sesarmidae , and Varunidae . Shrimps of the families Alpheidae , Atyidae , and Palaemonidae were also recorded from various caves in different parts of the archipelago ( Cai & Anker, 2004; Cai & Husana, 2009). There are also other smaller invertebrates present in the same cave systems, including amphipods ( Melitidae ), copepods ( Boholiniidae ), isopods ( Cirolanidae ), and gastropods ( Neritiliidae ) ( Fosshagen & Iliffe, 1989; Bruce & Iliffe, 1992; Kano & Kase, 2004; Sawicki, Holsinger & Iliffe, 2005). Still, many undescribed species from various caves in different parts of the Philippines were observed and collected by the second author during speleological expeditions, and this material awaits further study.

Until now, no cave-dwelling Barbodes has been documented from the Philippines. Barbodes pyrpholeos is not only the first known cave-dwelling cyprinid described from the Philippines, but is also only the second species of cave-dwelling cyprinid reported from the Sundaic islands. Barbodes microps , the first species of cave-dwelling cyprinid reported from the Sundaic islands, was described by Günther in 1868 from material collected in Central Java. Little information is available for B. microps , but it appears to be pigmentless (see Kottelat et al., 1993: pl. 16).

Along with the collection of Barbodes pyrpholeos , pigmented and eyed Barbodes were obtained from surface waters in close proximity to the Ugnop Cave system. Based on morphological characters and geographic location, these individuals were identified as Barbodes montanoi . Based on geographic proximity, B. montanoi may be a close relative of B. pyrpholeos , but this subject requires further investigation with morphological and molecular characters and is beyond the scope of this study. As B. montanoi is poorly known, we take this opportunity to redescribe this species.

RAFFLES BULLETIN OF ZOOLOGY 2021

Figures

Fig.1. Barbodes pyrpholeos, in situ photograph of an immature fish near lower part of second author’s leg, about 60 mm SL, Ugnop Cave system. (Photograph by Daniel Edison M. Husana)

Fig. 2. Barbodes pyrpholeos, freshly caught individual of about 100 mm SL, Ugnop Cave system. (Photograph by Daniel Edison M. Husana)

Fig. 3. Barbodes pyrpholeos, freshly captured individual (likely to be the holotype), about 100 mm SL, Ugnop Cave system. (Photograph by Daniel Edison M. Husana)

Fig. 4. Barbodes pyrpholeos, PNM 15649, holotype, 104.1 mm SL; radiograph below. (Photograph and radiograph by Tan Heok Hui)

Fig. 5. Barbodes pyrpholeos, ZRC 61230, 92.0 mm SL, Ugnop Cave system, dorsal and lateral views; right side reversed (note large gaped mouth and broad head; left pectoral fin excised). (Photographs by Tan Heok Hui)

Fig. 6. Barbodes pyrpholeos, PNM 15650, 86.6 mm SL, Ugnop Cave system, dorsal and lateral views (note bulging eyes and broad head). (Photographs by Tan Heok Hui)

Fig. 7. Barbodes pyrpholeos, Ugnop Cave system. Top: ZRC 61230, 68.8 mm SL; bottom: ZRC 61232, 59.0 mm SL. (Photographs by Tan Heok Hui)

Fig. 8. Barbodes pyrpholeos (left), 104.1 mm SL, showing smooth last unbranched dorsal-fin ray (damaged, broken mid-way but healed); Barbodes montanoi (right), 62.8 mm SL, showing last unbranched dorsal-fin ray with weak serrations. (Images by Tan Heok Hui)