Paralaubuca typus Bleeker, 1864

(Figures 1, 2, 5, 6)

Paralaubuca typus Bleeker, 1864:16 .

Type locality: Thailand: Ajuthia [Ayutthaya] and Bangkok. Lectotype: MNHN 1867, designated by Bănărescu (1971:348, fig. 1).

Chela paralaubuca Günther, 1868:337 . Unnecessary replacement name for Paralaubuca typus Bleeker, 1864 .

Pseudolaubuca lateralis Sauvage, 1876:98 .

Type locality: Cochinchine: rapids of the Mekong. Lectotype: MNHN 3932, designated by Bănărescu, 1971:348.

Chela stigmabrachium Fowler, 1934:109, fig. 62.

Type locality: Thailand: Chiang Rai Province: Mekong River at Chieng Sen. Holotype: ANSP 57458

Culter riveroi Fowler, 1935:108, fig. 34.

Type locality: Thailand: Bangkok. Holotype: ANSP 60803.

Paralaubuca typus was described by Bleeker (1864) based on four specimens, 112–120 mm TL, from the Chao Phraya River in Ajuthia [Ayutthaya] and Bangkok, Thailand. The specimens were described as having 7 branched dorsal-fin rays, 13 pectoral-fin rays, 9 pelvic-fin rays, 29–30 branched anal-fin rays, and 17 branched caudal-fin rays, and had black pigment on the pectoral fins. In his revision of Paralaubuca, Bănărescu (1971) selected a lectotype (MNHN 1867), then 92.1 mm SL, and paralectotypes (MNHN 1865 and 1866), 92–96.8 mm SL. Our count of lateral-line scales from the image of the lectotype (Figure 6A) is 63.

Pseudolaubuca lateralis was described by Sauvage (1876) from the Mekong River in Cochinchine—presumably in Cambodia or Laos (Kottelat 2013). Little information on the morphology and no biometric values were provided. Sauvage (1881) relegated Pseudolaubuca lateralis to the synonymy of Paralaubuca typus Bleeker 1864 . Bănărescu (1971) examined 149 syntypes of P. lateralis, 87.0–133.0 mm SL, designated a lectotype (MNHN 3932), and agreed with Sauvage (1881) that P. lateralis is a synonym of P. typus . For the types, Bănărescu gave an average branched anal-fin ray count of 26.3 and a range of 36–37 gill rakers. Our count of lateral-line scales from the image of the lectotype (Figure 6B) is 60, and the estimated SL is 103 mm.

Chela stigmabrachium was described by Fowler (1934) from 7 specimens 63–160 mm in total length (TL) from the Mekong River at Chiang Sen in northern Thailand. It was described as having 7 branched dorsal-fin rays, 15 pectoral-fin rays, 9 pelvic-fin rays, 31 gill rakers, 25–27 branched anal-fin rays, and the pigment on the pectoral fin as a “variable large medial blackish or dusky area.” Bănărescu (1971) gave the SL of the holotype (Figure 6C) as 127.5 mm SL; we found it to be 122.4 mm SL.

Bănărescu (1971) considered Chela stigmabrachium a valid species of Paralaubuca based on black pigment on the pectoral fin but noted it otherwise to be identical to P. typus . However, P. typus often has black pigment on the pectoral fin, even noted by Bleeker (1864) in the original description of the species. After examining the holotype, we agree with Rainboth (1996) that C. stigmabrachium is a synonym of P. typus .

Culter riveroi was described by Fowler (1935) from a single specimen 153 mm TL (Figure 6D) collected in Bangkok, Thailand. It was described as having 53 lateral-line scales, 7 branched dorsal-fin rays, 25 branched anal-fin rays, 9 pelvic-fin rays, 14 pectoral-fin rays, and 42 gill rakers. Bănărescu (1971) examined the holotype and found it to be 125.7 mm SL; we found the holotype to be 119.3 mm SL and to have 61 lateral-line scales. Nothing in the original or subsequent published descriptions distinguishes C. riveroi from P. typus, and we consider it a synonym of P. typus .

Diagnosis. Paralaubuca typus is most similar to P. barroni but distinguished by having 31–51 vs. 22–29 rakers on first gill arch, average of 58.4 vs. 54.8 lateral-line scales, and reaching much larger size, 152.5 vs 115.0 mm SL. Paralaubuca typus is distinguished from P. harmandi by having 51–68 vs. 70–87 lateral-line scales, usually 24–29 vs. usually 22–24 branched anal–fin rays, 20–28 (usually 26 or fewer) vs. 26–33 (usually 28–32) scales around caudal peduncle, 31–51 vs. 29–33 rakers on first gill arch, and 38–41 (usually 39–40, average=39.3, n=14) vs. 41–42 (usually 42, average=41.9, n=9) total vertebrae. Paralaubuca typus has longer anal fin and anal-fin base, and larger eye (Table 9) than P. harmandi . It also has shorter lower lip than P. harmandi (Table 9) reflecting proportionally shorter dentary (Figure 5). Paralaubuca typus is further distinguished from P. harmandi osteologically as described above and shown in Figure 5. Paralaubuca typus, reaching 152.5 mm SL, is smaller than P. harmandi, which reaches 265 mm SL.

Description. See description of genus. In three collections of P. typus from the Chao Phraya River basin in which gonads were examined to confirm the sex, females (n=17) were significantly deeper bodied than males (n=14) and reached a much larger size (152.5 vs. 116.1 mm SL) (Figure 7). In addition to being more slender, males at least seasonally have a more pronounced black midlateral stripe and more black pigment on the pectoral fin and edge of the caudal fin.

Distribution. Paralaubuca typus is known from the Chao Phraya, Mae Klong, and Tachin River basins of Thailand, and the Mekong River basin of Cambodia, Laos, Thailand, and Vietnam (Figure 8C).

Most observations and collections of P. typus have been in flowing water in moderate to large rivers. A few specimens have also been collected in impoundments. Paralaubuca typus is widespread and common in the Chao Phraya and Mekong River basins, but in the Mae Klong it is known only from a few localities in the lower basin and has not been documented there since the 1960s. However, it occurs in the adjacent Tachin River basin, and targeted sampling may reveal its occurrence in the lower Mae Klong River basin.

Paralaubuca typus:

Chao Phraya River basin: Thailand: Ang Thong Province: UF 193722, 1, 49.7, Chao Phraya R., Pa Mok, 14.45141, 100.45999, Tangjitjaroen, W., 11 Feb 2014 . Ayutthaya Province: UF 248528, 5, 82.6 – 103.3, Chao Phraya R., 14.17823, 100.50190, Tangjitjaroen, W., 21 Jun 2022; UF 193653, 2, 85.5 - 90.7, Chao Phraya R. at Bang Sai Fishing House, 14.17823, 100.50190, Tangjitjaroen, W., 14 Mar 2023; UF 249257, 7 of 33, 77.3–109.3, same locality as UF 193653, Miguez, J. & Tangjitjaroen, W., 20 Feb 2023; UF 249413, 4, 54.4 -87.0, same locality and collector as UF 193653, 18 Nov 2022; UF 249527, 16 of 33, 78.1–100.7, same locality and collector as UF 193653, 7 Feb 2023; UF 249536, 17 of 22, 67.5–87.4, same locality and collector as UF 193653, 8 Feb 2023 . Bangkok Province: USNM 103297, 2, 141.9 – 145.7, pond in Bangkok, 13.84101, 100.57557 (est.), Smith, H. M., 18 Mar 1924; USNM 108124, 4, 68.2 – 77.7, Chao Phraya R., 13.76121, 100.49172 (est.), Smith, H. M., 4 Jan 1925 ; USNM 108125, 2, 93.1 – 99.3, canal in Bangkok, 13.78604, 100.46600 (est.), Smith, H. M., 8 Sep 1934 . Bangkok [now Samut Prakan] Province: ANSP 60803, holotype of Culter riveroi, 119.3, Chao Phraya R., 13.70562, 100.56186, Deschauensee, R. M., May 1934 ; ANSP 89432, 7 of 18, 98.0–110.2, Chao Phraya R., 13.70562, 100.56186, Deschauensee, R. M., 1936. Chainat Province: UF 249815, 2, 79.2 – 121.4, Chao Phraya R., 15.16195, 100.18802, Grudpan, C., no date. Chiang Mai Province: NIFI 00060, 2, 88.2 – 95.5, Mae Klang R., 18.49496, 98.66763 (est.), Kannasute, C., 15 Jan 1976 ; NIFI 04314, 5 of 11, 80.6–83.3, Ping R., 18.26798, 98.64147 (est.), no collector information, 14 Jan 1976 ; UF 185735, 4 of 11, 94.8–106.4, market in Hod (town) Ping R., 18.19250, 98.61277, Page, L. M., 7 Jan 2012 ; UF 248515, 1, 124.2, Maesoi Dam on Ping R., 18.26810, 98.64170, Tangjitjaroen, W., 31 Oct 2021 . Kamphaeng Phet Province: UF 248615, 4, 95.6 – 133.2, Ping R., 16.53040, 99.49430, Tangjitjaroen, W., 8 Feb 2022; UF 249459, 2, 63.7 – 97.9, Ping R., Ruen Thai Ban Rim Nam, Muang, 16.53063, 99.49418, Tangjitjaroen, W., 19 Nov 2022 ; UF 249498, 5, 107.7 – 120.7, same locality and collector as UF 249459, 6 Feb 2023; UF 193797, 7, 116.1 – 152.5, same locality and collector as UF 249459, 10 Feb 2024 . Nakhon Sawan Province: UF 248841, 4, 86.3 – 96.6, Chao Phraya R. at confluence of Ping and Nan rivers, market in Nakhon Sawan, 15.70025, 100.13874, Randall, Z., et al., 8 Jun 2022 . Petchabun Province: USNM 103290, 2, 88.4 – 100.5, market, Pasak R., 15.46072, 101.10240 (est.), Smith, H. M., 27 Feb 1925 . Pitsanulok Province: ANSP 89373, 4 of 9, 113.3–120.8, Nan R., 16.82357, 100.26064, Deschauensee, R. M., 1936; ANSP 89374, 6 of 10, 87.5–110.8, Nan R., 16.82357, 100.26064, Deschauensee, R. M., 1936; ANSP 89378, 5 of 14, 102.7–113.8, Nan R., 16.82357, 100.26064, Deschauensee, R. M., no date; NIFI 04600 –B, 1, 59.2, Bang Kaeo canal, 16.81285, 100.13272 (est.), Suksri, S., 20 Oct 2010 ; NIFI 04606, 5 of 10, 61.2–71.4, Yom R., 16.83461, 100.05573 (est.), Suksri, S., 3 Aug 2011 . Saraburi Province: UF 176518, 4, 104.3 – 114.3, mark et al ong Rapeepat canal adjacent to Highway 1, 14.20777, 100.85555, Tangjitjaroen, W., 25 Oct 2009 . Sukothai Province: ANSP 87398, 4 of 5, 62.6–111.9, Mae Poon (or Mae Phun) a small tributary of Yom R., 17.66667, 99.70 (est.), Deschauensee, R. M., 1936 ; ANSP 88043, 2, 60.4 – 63.8, same data as ANSP 87398; ANSP 89541, 5 of 16, 97.1–105.1, same data as ANSP 87398; NIFI 04713, 4, 48.9 – 56.1, Sam Puang canal, 16.88253, 99.82786 (est.), Suksri, S., 21 Jan 2010 .

Mae Klong River basin: Thailand: Kanchanaburi Province: NIFI 00082, 2, 116.5 – 125.9, Mae Klong R., 13.99587, 99.53888 (est.), Tiancharoen, P., 1 Jun 1966; UMMZ 195833, 7 of 13, 80.1–93.1, Khwae Noi R., ca. 20 km upstream of Kanchanaburi, 13.90182, 99.46191, Lagler, K. F., et al., 23 Mar 1965; UMMZ 195849, 1, 82.3, Mae Klong R. at Kanchanaburi (confluence of Khwae Noi and Khwae Yai), 14.01898, 99.52661, Lagler, K. F., et al., 23 Mar 1965 ; UMMZ 195863, 5 of 9, 100.6–121.9, Khwae Yai about 10 Km upstream of Kanchanaburi, 13.93990, 99.48946, Lagler, K. F., et al., 24 Mar 1965 ; UMMZ 195875, 5, 58.6 – 98.8, Khwae Yai, ca. 8 km upstream of Kanchanaburi, 13.94431, 99.47435, Lagler, K. F., et al., 24 Mar 1965 . Ratchaburi Province: UMMZ 195896, 5, 75.4 – 124.4, Mae Klong R. at Ban Pong, 2 km downstream, 13.81823, 99.86522, Lagler, K. F., et al., 25 Mar 1965 ; UMMZ 196219, 1, 61.4, market in vicinity of Ratchaburi, 13.54110, 99.82483, Lagler, K. F. and Thiemed, J., 14 Nov 1964 .

Mekong R. basin: Cambodia: Battambang Province: UMMZ 232403, 3, 67–73, 13.25629, 103.60108 (est.), Rainboth, W. J., et al., 8 Feb 1995 . Phnom Penh Province: UMMZ 234716, 3 of 4, 62.9–69.8, Prek Muk Kandal across Tonle Sap Phnom Penh, 11.66661, 104.86334, Rainboth, W. J., 1 Mar 1996 ; UF 190474, 5 of 6, 61.9–97.1, morning market at Stung Treng, 13.53061, 105.97102, Page, L. M., 22 May 2016 . Stung Treng Province: UMMZ 232351, 1, 53.7, Mekong R. rapids, 13.46667, 105.95, Rainboth, W. J., et al., 29 Jan 1995; UMMZ 234670, 5 of 10, 53.3–66.0, Mekong R., 13.61666, 106.050, Rainboth, W. J., 14 Feb 1996 . Laos: Bokeo Province: UMMZ 241055, 1, 57.1, Mekong R., 9 km upstream of Houay Xai, 20.36667, 100.36667, Rainboth, W. J. & Virawong, S., 22 Apr 1997 . Champasak Province: UMMZ 235309, 3, 96–137, Mekong R. at Ban Hang Khone, 13.93333, 105.93333, Baird, I., no date . Savannakhet Province: UMMZ 241585, 13, 58.1–98.8 mm, Xe Bangfai at Ban Hatkhamhiang, 17.06667, 104.91667, Rainboth, W. J., 27 Mar 1998 ; UMMZ 241779, 7, Savannakhet market, 16.58333, 104.76667, Rainboth, W. J., 4 Jan 1998 . Thailand: Chiang Rai Province: ANSP 57458, holotype of Chela stigmabrachium, 122.4, Mekong R. at Chieng Saen, 20.27540, 100.08921, Deschauensee, R. M., 10 Feb 1933 ; ANSP 57459–57464, 4 of 6 paratypes of Chela stigmabrachium, 109.7–122.5, Mekong R. at Chieng Saen, 20.27540, 100.08921, Deschauensee, R. M., 10 Feb 1933 ; UF 170314, 1, 80.7, Kok R., 19.96958, 99.96868, Page, L. M., et al., 12 Nov 2007 ; UF 178162, 1, 147, market in Chiang Saen, Mekong R., 20.33583, 100.08777, Tangjitjaroen, W. and Page, L. M., 15 May 2010 . Khon Kaen Province: UMMZ 236950, 1, 90, Pong Neeb, trib. Pong R., 16.7738, 102.62127, Witt, et al., no date . Maha Sarakham Province: UMMZ 195795, 1, reservoir at Maha Sarakhan, 16.17195, 103.26605, Lagler, et al., 12 Feb 1965 . Nakhon Phanom Province: CAS 226022, 5 of 6, 98.4–106.1, Mekong R. mainstream at Bung Kla, ca. 140 km northwest of Nakhon Phanom, 18.31239, 103.99147, Roberts, T. R., 7 Jul 1985 ; UF 249821, 5 of 8, 59.1–62.6, market at Mekong R., 17.40384, 104.78788 (est.), Grudpan, C., 4 Sep 1997 . Nong Khai Province: NIFI 01149, 7, 74.3 – 119.1, Mekong R., 17.88465, 102.74601 (est.), no collector information, no date; UMMZ 195489, 1 of 62, 47 Mekong R. at Ban Si Chiang Mai, 17.95961, 102.58834, Lagler, K. F., et al., 5 Feb 1965 . Sisaket Province: NIFI 04252, 1 of 2, 49.9, Bung Kra Sang Swamp, 14.97323, 104.62848 (est.), no collector information, 3 Dec 1993 ; UF 248754, 1, 95.7, Mun R. at Rasi Salai Dam and market specimens from Rasi Salai, 15.34318, 104.09897, Randall, Z., et al., 6 Jun 2022 . Ubon Ratchathani Province: ANSP 87239, 6, 82.1 – 113.6, Khemmarat on Mekong R., 16.04409, 105.22381, Deschauensee, R. M., 1936 ; ANSP 203499, 3, 55.3 – 81.0, market at Warinchamrap on Mun R., 15.19928, 104.86521 (est.), Bornbusch, A., 26 Mar 1987 ; AUM 56042, 4 of 9, 61.1–81.1, Mun R. at Bung –ma–laeng Village, 18.1 km east of Ubon Ratchathani, 15.27328, 105.02805, Armbruster, J. W., et al., 7 Jan 2012 ; NIFI 04156, 1, 89.7, Mekong R., 15.31783, 105.49130 (est.), Vidthayanon, C., et al., 29 May 1989 ; NIFI 04295, 1, 65.5, Mun R., 15.30859, 105.49353 (est.), no collector information, 23 Sep 1992 ; UF 249823, 3, 77.4 – 78.3, Mekong R., 15.31808, 105.49122 (est.), Grudpan, C., 16 Jul 2005 ; UF 249819, 1, 89.4, same locality and collector as UF 249817, 5 Jul 2008; UF 249820, 7, 68.5 –77.0, Mun R., 15.13215, 104.70467 (est.), Grudpan, C., 19 Aug 2005 ; UF 249822, 3 of 13, 47.4–75.4, Mekong R., 15.57147, 105.62429 (est.), Grudpan, C., 18 Nov 2012 ; UMMZ 218829, 2, X-rays, Mun R. at Ban Dan, 15.30059, 105.48076, Songrad & Buskirk, 7 Apr 1975 ; UF 170312, 6 of 16, 64.4–119.4, from fishers at Mun R. in Warinchumrab, 15.17861, 104.70665, Page, L. M., et al., 16 Nov 2007 ; UF 249813, tissue only, same data as UF 170312; UF 170313, 2, 73.7 – 89.6, Rim Mun Market in Ubon Ratchathani, from Mun R., 15.22438, 104.8590, Page, L. M. and Tangjitjaroen, W., 15 Nov 2007 ; UF 245585, 5 of 8, 61.3–83.6, Mun R. southeast of Khong Chiam, 15.30803, 105.49011, Page, L. M., et al., 23 Jan 2020 ; UF 249374, 11 of 30, 76.8–88.6, Rim Mun Market in Ubon Ratchathani: Mun R., 15.22438, 104.8590, Miguez, J., et al., 28 Feb 2023 ; USNM 271327, 5 of 10, 65.3–84.1, market in Ubon Ratchathani, 15.22416, 104.85872 (est.), no collector information, 4 Jun 1971; USNM 271540, 2 of 13, 66.6–70.5, market in Ubon Ratchathani at edge of Mun R., 15.22416, 104.85872 (est.), no collector information, 14 Sep 1971; USNM 305767, 3, 55.3 – 63.2, market in Warinchamrap, 15.19928, 104.86521 (est.), Bornbusch, A. H., 26–30 Mar 1987 . Vietnam: Phong Dinh Province: UMMZ 218151, 2, 38–41, Bassac R., 0.5 km downstream of Can Tho, 10.04, 105.80599, Arden, R. & Minh, D., 3 Nov 1974 . Song Hau River basin: An Giang Province: UF 241500, 4, 42.8 – 46.7, An Phu District, Chau Doc R., 10.79833, 105.07305, Thai, T., 10 Sep 2013 . Vam Co River basin: Long An Province: UF 241488, 5 of 8, 64.7–72.9, Vam Co Tay R., 10.78316, 105.92966, Thai, T., 17 Sep 2013 .

Tachin River basin: Thailand: Nakhon Pathom Province: ANSP 212803, 3, 57.9 – 117.6, Tachin River, 14.03431, 100.1745, Tangjitjaroen, et al., 8 May 2024 .