Glyptothorax lanceatus, Ng, Heok Hee, Jiang, Wan-Sheng & Chen, Xiao-Yong, 2012

Ng, Heok Hee, Jiang, Wan-Sheng & Chen, Xiao-Yong, 2012, Glyptothorax lanceatus, a new species of sisorid catfish (Teleostei: Siluriformes) from southwestern China, Zootaxa 3250, pp. 54-62 : 55-59

Glyptothorax lanceatus , sp. nov.

( Fig. 1 )

Type material. Holotype: KIZ 2006009835, 130.0 mm SL; China: Yunnan, Baoshan Prefecture, Bawan township, Nujiang at Mangdan village; 24°56'00"N 98°53'29"E, 690 m asl.; local fisherman, 4-5 May 2006.

Paratypes: KIZ 2006009868 (1), 138.2 mm SL; CAS 226105 (1), 135.3 mm SL; China: Yunnan, Baoshan Prefecture, Longling County, Bizhai township, Nujiang near Sanjiangkou; 24°25'18.0"N 98°58'21.2"E, 645 m asl.; local fisherman, 28 April 2006. CAS 226138 (1), 129.2 mm SL; China: Yunnan, Baoshan Prefecture, Nujiang at new bridge on toll road between Baoshan and Tengchong, 24°56'0.0"N 98°53'29"E, 690 m asl.; local fishermen, 4– 5 May 2006.

Diagnosis. Glyptothorax lanceatus can be distinguished from congeners in the Irrawaddy, Mekong and Salween River drainages in having the combination of elongate, ovoid tubercles on dorsal surface of head, small interorbital distance (20.2–22.1% HL), width of adhesive apparatus 1.60–1.74 times in its length, and long caudal peduncle (20.3–21.8% SL). The following additional characters serve to further distinguish this species: length of nasal barbel 18.1–21.5% HL; length of maxillary barbel 86.2–91.1% HL; length of inner mandibular barbel 23.8– 28.2% HL; length of outer mandibular barbel 42.8–49.1% HL; eye diameter 6.8–8.3% HL; head length 23.0– 25.1% SL; head width 16.3–18.8% SL; depressed area in thoracic adhesive apparatus not wholly enclosed by ridges; ridges of thoracic adhesive apparatus not extending onto gular region;10–13 serrations on posterior edge of pectoral spine; pectoral-fin length 21.1–24.5% SL; length of adipose-fin base 12.2–13.2% SL; dorsal-to-adipose distance 23.0–24.8% SL; distally expanded neural spines in vertebrae between dorsal and adipose fins; body depth at anus 12.4–14.8% SL; post-adipose distance 18.7–20.3% SL; caudal peduncle depth 6.7–7.4% SL; 40–41 vertebrae; reaching to at least ca. 170 mm TL in size; and uniformly dark-colored body generally devoid of pale or dark markings.

Description. Biometric data are presented in Table 1 . Head depressed, body subcylindrical. Dorsal profile rising evenly from tip of snout to origin of dorsal fin, and then sloping gently ventrally from origin of dorsal fin to end of caudal peduncle. Ventral profile flat to anal-fin base, then sloping gently dorsally from anal-fin base to end of caudal peduncle. Anus and urogenital openings located at vertical through middle of adpressed pelvic fin. Skin tuberculate, with tubercles uniformly arranged on sides of body; tubercles consisting of elongate ridges, particularly prominent on dorsal surface of neurocranium. Lateral line complete, midlateral. Vertebrae 20+20=40 (1) or 20+21=41 (1).

Head depressed and broad, triangular when viewed laterally. Snout gently convex when viewed from above. Anterior and posterior nares separated only by base of nasal barbel. Eye small, ovoid, horizontal axis longest, located on dorsal half of head. Gill openings broad, extending from directly beneath post-temporal to isthmus.

Barbels in four pairs. Maxillary barbel thick, extending to base of last pectoral-fin ray. Nasal barbel slender, extending to midway between its base and anteriormost point of orbital margin. Inner mandibular barbel extending to one-third of distance between its base and base of pectoral spine. Outer mandibular barbel originating posterolateral of inner mandibular barbel, extending to two-thirds of distance between its base and base of pectoral spine.

Mouth inferior, premaxillary tooth band partially exposed when mouth closed. Oral teeth small, villiform, in irregular rows on all tooth-bearing surfaces. Premaxillary teeth in single crescentic band. Dentary teeth in two patches separated by narrow gap at midline. Palate edentate.

Thoracic adhesive apparatus present, consisting of skin ridges (striae) in an elongate oval field extending from isthmus to middle of pectoral-fin base and with narrow median depression on posterior third. Striae oriented anterodistally, radiating from median depression.

Dorsal fin nearer to snout-tip than to adipose-fin origin, with I,6 (4) rays; dorsal margin of fin truncate; anterior margin of spine smooth, posterior margin with 5–8 small serrations. Anterior nuchal plate element triangular, with saddle-shaped lateral extensions and extensive contact with posterior nuchal plate element. Adipose fin straight anteriorly and angular posteriorly. Caudal fin deeply forked, lobes almost equal, with i,7,8,i (4) principal rays. Procurrent rays symmetrical, extending only slightly anterior to fin base, comprising of 8–9 rays. Anal-fin origin slightly anterior to vertical through adipose-fin origin. Anal fin with straight anterior margin and straight or slightly concave posterior margin; with iii,10* (2) or iv,10 (2) rays. Pectoral fin with I,11 (4) rays; posterior fin margin straight; anterior margin of spine smooth, posterior margin with 10–13 serrations. Pelvic-fin origin at vertical through posterior end of dorsal-fin base. Pelvic fin with slightly convex anterior margin and i,5 (4) rays; tip of adpressed fin falling just short of anal-fin origin.

Coloration. In life: Dorsal and lateral surfaces of head and body bronze, fading to light gray ventrally. All fins with brownish fin rays and hyaline membranes. Thoracic adhesive apparatus reddish ( Fig. 2 ).

In 75% ethanol: Dorsal and lateral surfaces of head and body dark grayish brown. Ventral surfaces of head and body light brown. Body without distinct pale blotches; indistinct patches sometimes present on cranial fontanel, and nuchal plate elements. Lateral line evident as narrow pale stripe. Pale mid-dorsal stripe delineating tips of expanded neural spines of vertebrae between dorsal and adipose fins in some individuals. Base of all fins dark brown, fading to yellow or hyaline distally. Fin rays with scattered melanophores; fin membranes hyaline. Maxillary and nasal barbels grayish brown dorsally, light brown ventrally.

Distribution. Known from the middle reaches of the Salween River (Nujiang) drainage in Yunnan, China ( Fig. 3)

Etymology. The specific epithet comes from the Latin adjective lanceatus , meaning “made into a lance”. This name is used in allusion to the narrow thoracic adhesive apparatus of this species, which vaguely resembles the tip of a lance.

Phylogenetic position. Phylogenetic analyses based on maximum likelihood (ML) and Bayesian inference ( BI) methods revealed identical phylogenetic position of this species in both cases. It is a member of Clade I (sensu Jiang et al., 2011), and is strongly supported as a sister species to G. longjiangensis (with posterior probability/ML bootstrap values of 0.99 and 0.65 respectively).

Figures

FIGURE 1. Glyptothorax lanceatus, sp. nov., holotype, KIZ 2006009835, 130.0 mm SL; China: Yunnan, Baoshan prefecture, Bawan township, Nujiang at Mangdan village.

FIGURE 2. Glyptothorax lanceatus, sp. nov., holotype, KIZ 2006009835. 130.0 mm SL, showing live coloration.

Tables

TABLE 1. Biometric data for Glyptothorax lanceatus (n = 4).

Standard length (mm) %SL Predorsal length	Holotype Range KIZ 2006009835 130.0 129.2–138.2 37.0 33.2–37.0	Mean±SD 35.2±1.47
Preanal length Prepelvic length	62.8 62.8–65.2 46.8 44.9–48.1	63.7±0.99 46.6±1.14
Prepectoral length Length of dorsal-fin base Dorsal-spine length Length of anal-fin base	20.3 19.6–22.9 12.1 10.7–12.1 16.3 14.3–16.3 16.2 15.2–16.3	20.7±1.31 11.6±0.53 15.3±0.71 15.9±0.43
Pelvic-fin length Pectoral-fin length	16.4 16.4–18.8 23.2 21.1–24.5	17.1±1.00 22.9±1.22
Pectoral-spine length Caudal-fin length Length of adipose-fin base Dorsal to adipose distance Post-adipose distance Caudal-peduncle length	17.8 16.6–17.8 29.5 27.5–31.3 12.6 12.2–13.2 24.4 23.0–24.8 18.7 18.7–20.3 20.3 20.3–21.8	17.4±0.50 29.1±1.50 12.8±0.42 23.9±0.73 19.7±0.64 21.2±0.61
Caudal-peduncle depth Body depth at anus Head length Head width	7.4 6.7–7.4 14.8 12.4–14.8 25.1 23.0–25.1 18.8 16.3–18.8	7.1±0.26 13.3±0.91 24.2±0.96 17.5±1.02
Head depth Length of adhesive apparatus	15.1 14.2–15.1 15.3 14.7–15.9	14.5±0.37 15.3±0.49
Width of adhesive apparatus Adhesive apparatus length:width ratio	9.5 8.7–9.5 1.60 1.60–1.74	9.2±0.37 1.67±0.06
%HL Snout length	52.5 50.3–53.5	52.2±1.16
Interorbital distance Eye diameter	20.9 20.2–22.1 8.3 6.8–8.3	21.2±0.73 7.4±0.60
Nasal barbel length Maxillary barbel length Inner mandibular barbel length Outer mandibular barbel length	18.1 18.1–21.5 91.1 86.2–91.1 28.2 23.8–28.2 46.0 42.8–49.1	19.8±1.25 88.1±2.00 26.1±1.65 46.0±2.23