Holotype. Indonesia • 63.8 mm SL; Java Island, West Java Province, Bogor Regency, Klapanunggal District, Nambo Village, Klapanunggal karst area, subterranean cave system of Cisodong 1 Cave; altitude 212 m a. s. l.; 3 July 2022; M. I. Willyanto, M. Yusmaryudi, and A. Novriansyah legs.; hand net; MZB.26657.

Paratype. MZB.26656, 73.0 mm SL, same data as holotype.

A species of Barbodes distinguished from all its congeners by the absence of eyes, as the eye is vestigially replaced by an orbital concavity being fully closed by an epidermal layer, while lacking the orbital rim. The species is also uniquely diagnosed by having relatively long pectoral and pelvic fins, with their adpressed tips each extending past the vertical through the insertion or origin of the next fin posterior to the tip, as to further pass posteriorly about two scales in anteroposterior; and by the presence of a relatively short and rounded axillary pelvic-fin scale, with tip not reaching posterior edge of pelvic-fin base. It is further distinguished from other Barbodes species in having by the following combination of characters: head length 32.9–35.3% of SL; pre-pectoral fin length 32.6–33.6% of SL; pre-pelvic fin length 54.0–59.6% of SL; pectoral fin length 26.0–31.4% of SL; pelvic fin length 21.5–24.4% of SL; anal-fin base length 9.7–11.8% of SL; caudal peduncle depth 13.2–18.2% of SL; body without pigmentation (black dots, bars, stripes, blotches, and triangular markings all absent from lateral surface); all fins with translucent interradial membrane and light cream to brownish rays.

Data for holotype presented first, followed by paratype data in parentheses (if different). Selected meristic and morphometric data given as percentages of SL in Table 1. General appearance shown in Figs 3A, B, 4A, B.

Figure 3. 

Barbodes klapanunggalensis sp. nov., MZB.26657, holotype, 63.8 mm SL A fresh B preserved C radiograph.

Figure 4. 

Barbodes klapanunggalensis sp. nov., MZB.26656, paratype, 73.0 mm SL A fresh B preserved C radiograph.

Body deep, laterally moderately compressed along anterior portion, progressively more compressed posteriorly. Greatest body depth at vertical through dorsal-fin origin. Dorsal profile of head posterodorsally slanted overall, with slight concavity along supraorbital profile. Limit between head and trunk marked by slight convexity of anterior predorsal profile. Dorsal profile of anterior body slightly arched anteriorly, nearly flat posteriorly (entirely posterodorsally slanted in paratype). Snout slightly rounded. Mouth subterminal, marked by two pairs of maxillary barbels, anterior pair shorter than posterior pair. Eye absent, ocular vestige marked by orbital concavity completely covered by skin, orbital rim absent. A short flap on upper posterior edge of low membranous tube associated with anterior nostril. Cycloid scales covering body, not extending onto fin rays or membranes, except basally on dorsal, anal, and caudal fins. Pelvic-fin axillary scale short, with rounded tip (slightly projecting on right side of holotype), not reaching vertical through posterior edge of pelvic-fin base (Fig. 5A, B).

Figure 5. 

Pelvic fin axillary scale in A, B Barbodes klapanunggalensis sp. nov., MZB.26657, holotype, 63.8 mm SL, MZB.26656, paratype, 73.0 mm SL, respectively C Barbodes binotatus, MZB.17843, 78.7 mm SL D Barbodes cf. microps, MZB.60, 89.8 mm SL. Arrow in A indicates posterior end of pelvic fin base membrane.

Dorsal fin with distal profile slightly concave, 4 (3) unbranched spinous rays, 8½ soft rays. First unbranched dorsal-fin ray very small; second ray about one-quarter length of third; last unbranched ray wide at base, progressively narrowing distally, with 10 (19) serrae along posterior edge of stiffened upper half. All soft dorsal-fin rays branched, first branched ray longest, slightly longer than fourth (third) unbranched ray. Pectoral fin slightly rounded, with 15 (14) rays; anteriormost ray unbranched, its adpressed tip extending past vertical through pelvic fin insertion. Pelvic fin with 10 (9) rays; anteriormost ray unbranched, its adpressed tip just reaching (extending past) anal fin origin; pelvic fin insertion about level with dorsal fin origin. Anal fin with 3 unbranched and 5½ branched rays; distal profile slightly concave. Caudal fin with 10+9 principal rays, uppermost and lowermost rays unbranched, symmetrically forked, tip of lobes pointed (rounded); upper caudal-fin lobe length 32.0 (34.8) % of SL; median caudal fin length 14.9 (18.7) % of SL; lower caudal-fin lobe length 31.8 (34.9) % of SL. Lateral-line scales complete 24+1 (22+1). Pre-dorsal scales 10. Scale rows above lateral line 4½, below lateral line at pelvic fin base 3½, below lateral line at anal fin base 3½. Scale rows in transverse line on caudal peduncle ½2/1/2½. Total gill rakers ca. 12, rakers short, length of longest raker on first gill arch about half length of adjacent gill filaments. Vertebrae 16+13 (14+14).

Coloration when fresh (Figs 3A, 4A). Head and body silvery-white, slightly cream to brownish dorsally, becoming lighter ventrally; indistinct longitudinal pinkish band on mid-lateral surface of body from below dorsal fin to caudal-fin base. All fins with semitranslucent interradial membrane and light cream to brownish rays.

Coloration in alcohol (Figs 3B, 4B). Head and body pale yellowish brown; body slightly darker dorsally, becoming lighter ventrally. All fins semi-translucent.

Currently known from a subterranean creek in Cisodong 1 Cave, in the karst area at Klapanunggal, Bogor, West Java, Indonesia (Fig. 2). The creek drains into Cileungsi River, a tributary of the Bekasi River Drainage that is eventually emptied into the Jakarta Bay.

The specific epithet klapanunggalensis is derived from the type locality, the Klapanunggal karst area, which includes the Cisodong 1 Cave, Nambo Village. The name reflects the unique habitat and geological significance of the Klapanunggal karst area, where the species is likely endemic.

The new stygobitic species B. klapanunggalensis can be distinguished from all congeneric species (including the epigean species B. binotatus allotopically co-ocurring in West Java), except the co-occurring subterranean species in Klapanunggal karst area B. cf. microps (see Kottelat et al. 1993: pl. 16) and a similarly subterranean Philippines species B. pyrpholeos (see Tan and Husana 2021: figs 1–7), in having a non-pigmented body (black dots, bars, stripes, blotches, and triangular markings all absent from body surface). The new species differs from B. binotatus, B. microps (including B. cf. microps), and B. pyrpholeos in lacking eyes (closed orbital concavity: Figs 3A, B, 4A, B; orbital rim absent: Figs 3A, 4B) [vs eyes present in B. binotatus, absent or present but usually small in B. microps (Weber and de Beaufort 1916; Kottelat et al. 1993: pl. 16; Haryono 2006: fig. 4A, B), and always present in B. pyrpholeos (Tan and Husana 2021: figs 1–7)]. In addition, B. klapanunggalensis sp. nov. can be distinguished from B. binotatus and B. microps by having a relatively short and rounded pelvic-fin axillary scale, its tip not reaching the posterior end of the pelvic fin base (Fig. 5A, B) (vs pelvic fin axillary scale slender, its tip distinctly beyond posterior end of pelvic fin base, in both of the latter; Fig. 5C, D)

Several morphometric characters of B. klapanunggalensis sp. nov. also differ from those of B. binotatus, B. microps (including B. cf. microps), and B. pyrpholeos (Fig. 6), including a long pectoral fin, its tip well beyond the pelvic-fin base origin (Figs 3, 4), 26.0–31.4% of SL [vs fin short, its tip not reaching origin of pelvic-fin base, 19.9–23.3 (mean 21.5) % of SL in B. binotatus, 20.2–23.8% in B. microps, and 18.6–22.6 (mean 20.9) % of SL in B. pyrpholeos (Tan and Husana 2021: figs 4–7, table 1]; a long pelvic fin, the depressed fin tip just reaching the anal-fin base origin (holotype) or well beyond (paratype) (Figs 3, 4) 21.5–24.4% of SL [vs fin short, tip usually not reaching anterior margin of anus, 17.2–20.5 (mean 19.0) % of SL in B. binotatus, 18.2–21.4% of SL in B. microps (tip just reaching anterior margin of anus in smallest specimen 48.6 mm SL), and 14.7–17.1% of SL in B. pyrpholeos (Tan and Husana 2021: figs 4–7, table 1]; relatively longer head 32.9–35.3% of SL [vs 25.3–29.7 (mean 27.3) % of SL in B. binotatus, 28.2–31.7% of SL in B. microps]; relatively greater pre-pectoral fin length, 32.6–33.6% of SL [vs 24.5–27.5 (mean 26.0) % of SL in B. binotatus, 26.0–30.2% of SL in B. microps]; and relatively greater pre-pelvic fin length, 54.0–59.6% of SL [vs 46.7–51.0 (mean 48.9) % of SL in B. binotatus, 48.6–54.9% of SL in B. microps]. In addition, B. klapanunggalensis sp. nov. also differs from B. pyrpholeos in having a greater anal-fin base length 9.7–11.8% of SL [vs 7.6–9.4 (mean 8.7) % of SL in the latter]; deeper caudal peduncle, 13.2–18.2% of SL [vs 11.6–12.9% of SL]; and dorsal, anal, and caudal fins with translucent interradial membranes and light cream to brownish rays (vs fins whitish anteriorly, orange posteriorly) (see Tan and Husana 2021: table 1, fig. 3, for B. pyrpholeos).

Figure 6. 

Relationships of A pectoral fin B pelvic fin C head D pre-pectoral fin, and E pre-pelvic fin lengths (all as % SL) to SL in Barbodes klapanunggalensis sp. nov. (triangles), Barbodes binotatus (stars), Barbodes microps (closed circles), and Barbodes cf. microps (opened circles).

The specimens of B. klapanunggalensis sp. nov. were collected from two small adjacent pools in a vertical cave, drained by a seasonal subterranean tributary (Fig. 2D, E). Both pools, containing clear water and fine clay substrate, were situated 27 m downward from the cave entrance and fed by water percolating from the cave floor. The water depth of the pools when the specimens were collected was about 15 cm, approximately one-third of the pool depth (Fig. 2E). A flowstone above the pools, which conveyed percolating water to the latter, was characterized by microgour deposits, in which two crustacean individuals—Stenasellus javanicus (Isopoda, Stenasellidae)—were observed. The fish in the pool remained stationary in still water, but began to actively swim when the water was disturbed.

The species was first observed in August 2020 by the second author (MIW)—together with teams from Latgab Caving Jabodetabeka, Indonesian Speleological Society (ISS), and Gema Balantara—in several small pools on the cave floor at two sites, each being on a different pitch (Fig. 2D). The first site comprised the two pools some 27 m depth from the entrance (see above), in which two barb individuals were observed. The second site was at the bottom of the cave (ca. 51.6 m depth), where more than 20 barb individuals were observed in pools with slow-flowing water. All of the barb individuals observed at that time lacked eyes and pigmentation. Individuals of the crustacean Stenasellus javanicus were observed crawling on the bottom of the pools. Although the fish was captured in video format (Fig. 1A, B), specimens were not collected.

Later in July 2022, MIW and colleagues returned to the cave and collected two specimens from the same two pools as described for the first site in 2020, thus likely the same two individuals observed prior. Since access to the cave was technically difficult, only the first two pools were visited, with no attempts made to collect individuals from the deeper part of the cave (see Fig. 2D).

To date, B. klapanunggalensis sp. nov. has been found only in Cisodong 1 Cave (61 m in length; 51 m in depth). Although currently known from a single cave, it is possible that the species is also present in neighboring caves given the network of interconnected tributaries comprising the subterranean river system in the Klapanunggal karst area. This is supported by the presence of the crustacean Stenasellus javanicus both in Cisodong 1 Cave and its type locality, Cikarae Cave, separated by about 6 km horizontal distance. Nevertheless, the overall distribution of the species is suspected to be likely limited to the Klapanunggal karst formation—an area of 66.64 km², only 9.96% (6.64 km²) of which is under Indonesian Government protection (referred to as Kawasan Bentang Alam Karst Bogor, Zona Klapanunggal/No. 24 K/40/MEM/2020) —considering the troglomorphic features of the species indicating great adaptation to a unique habitat type (i.e., subterranean pools supplied by percolated water) within a relatively close system. While the subterranean tributaries within the karst ecosystem are likely interconnected, the entire Klapanunggal karst formation is relatively disjunct from other similar karst formations in Java, especially those in southern Central Java and Yogyakarta. With such a limited distribution, the potential for disturbance to the habitat and survival of this cave fish is considerable, particularly due to the type locality being outside the protected karst area (Fig. 2C). However, direct threats from locals to the existence of B. klapanunggalensis sp. nov. have not been identified, given that the cave location is far from settlements and difficult to access. Nevertheless, the Klapanunggal karst environment faces potential threats from extractive industries, particularly from limestone mining, which is prevalent in the region (Fig. 2A). Such activities have been known to impact karst ecosystems elsewhere and may pose risks to the habitat of B. klapanunggalensis sp. nov. if not managed sustainably.

Barbodes klapanunggalensis sp. nov. meets the criteria of a threatened species, such as restricted distribution, distinctive habitat, small population, and high potential threat level. By comparison, the congener B. microps, also recognized as a cave species, despite having the eyes not fully reduced compared to B. klapanunggalensis sp. nov., is Vulnerable in the IUCN Red List (Lumbantobing 2020), and as a “protected species” under Indonesian Government regulations. Clearly, further assessment of the status of B. klapanunggalensis sp. nov., based on IUCN Red List criteria, is necessary so that strategies for the conservation of the species and habitat can be formulated properly.

The two type specimens of B. klapanunggalensis sp. nov. showed a striking difference in overall body shape, the paratype appearing to be relatively more deep-bodied and plumper (body depth and width 43.1% and 22.5% SL, respectively) than the holotype. Although this suggested initially that the paratype was likely female (female cyprinid fishes commonly having a deeper wider body than males), dissection of the right side of the abdomen of the former revealed that the large and broadly expanded abdomen was due to the accumulation of viscous fluid, rather than the presence of gonad with eggs. Despite that in-situ observations in 2020 noted more than 20 individuals in two different locations, their male/female composition is still unknown.

Barbodes microps was originally described as Barbus microps by Günther (1868) on the basis of five specimens collected from Java Island, Indonesia. However, examination of the syntypes in this study confirmed that only three syntypes (BMNH 1845.4.22.334–336, 77.8–103.4 mm SL) conformed to Barbodes microps, the remaining two syntypes (BMNH 1845.4.22.341–342, 42.2–43.8 mm SL) representing a different, more slender-bodied cyprinid species.

In this study, Barbodes microps is regarded as a valid species. However, it was clearly stated in the original description of Barbus microps that the syntypes (likely referring to the former three syntypes mentioned above) were characterized by dark spots on the bases of the anterior dorsal and caudal fins, which aligns with the diagnostic characteristics of Barbodes binotatus. Furthermore, the morphological features, including meristic and morphometric data of the three syntypes of Barbus microps, were consistent with those of non-type specimens of Barbodes binotatus examined in this study. Therefore, Barbodes microps is likely to be conspecific with Barbodes binotatus (see also Kottelat et al. 1993). A comparison between the type specimens of Barbus microps and those of Barbus binotatus is necessary to strengthen this conclusion.

Aside from initially containing multiple species, the type material of Barbus microps also has unclear information about the exact locality as no additional geographical references—other than being collected in Java—was provided along the specimens. This, coupled with the ambiguous species diagnosis in the original description, has made any taxonomical reassessments of the group rather difficult, as the identity of Barbodes microps cannot easily be pinpointed to any single subterranean river system in Java; some of the systems—given their each being highly isolated and hydrologically disconnected from the others—may harbor their own hypogean barb species.

In fact, Weber and de Beaufort (1916) reported Barbodes microps (treated as Puntius microps) based on non-type material collected from Gunung Sewu karst area in the central southern region of Java. It is, however, uncertain whether the specimens examined by the latter authors is really in the same subterranean system where the type specimens of Barbus microps were collected. Despite this uncertainty, we are certain that B. klapanunggalensis sp. nov. is not identical to these specimens from central Java not only because it is distinct morphologically, but also because the Klapanunggal karst area is hydrologically disconnected from all the other karst areas in Java, especially the one in Gunung Sewu karst area.

Another population also from the Klapanunggal karst area yet collected much earlier—herein referred to as Barbodes cf. microps (MZB 60)—is also likely to be conspecific with B. binotatus. The specimens of MZB 60 were collected from a creek in Sileuwi Cave that has its own spring and continuously flows downstream to a larger tributary of the Bekasi River. The creek is also situated at a lower altitude than the type locality of B. klapanunggalensis sp. nov. (Cisodong 1 Cave), the latter of which contrastingly encompasses a pool-type habitat with no direct fluvial connectivity to the surrounding tributaries. In other words, the fluvial connectivity in the Sileuwi Cave to surrounding tributaries may allow gene flow between the epigean and hypogean populations of B. binotatus. In contrast, the hydrological isolation of the Cisodong 1 Cave is likely to maintain genetic isolation in B. klapanunggalensis as manifested in its distinct morphology.

The discovery of this new species of cave fish brings to six the total number of cave fish species endemic to Indonesia, the previously recorded species being: Barbodes microps, Grammonus thielei Nielsen & Cohen, 2004, Bostrychus microphthalmus Hoese & Kottelat, 2005, Diancistrus typhlops Nielsen, Schwarzhans & Hadiaty, 2009, and Oxyeleotris colasi Pouyaud, Kadarusman & Hadiaty, 2012. Among the six species, only Barbodes klapanunggalensis sp. nov. and Barbodes microps have been recorded from Java (Rahmadi et al. 2018; Fig. 2B), the remaining species being known from various karst areas around Sulawesi Island and West Papua (Pouyaud et al. 2012).