Pareuchiloglanis posteranalis, Dao & Li & Yang & Zhou, 2020

Dao, Wei, Li, Xu, Yang, Hong-Fu & Zhou, Wei, 2020, Pareuchiloglanis (Teleostei: Sisoridae) from the Pearl River, China with description of three new species, Journal of Fish Biology 96 (1), pp. 23-36 : 30-32

3.3 | Pareuchiloglanis posteranalis sp. nov.,

Figure 3c

3.3.1 | Holotype

SWFC 1908004, 106.0 mm L S; China: Yunnan Prov.: Wenshan Pref.: Guangnan Co.: Zhetai Town: Datian Village : Nawangxiao-he, a stream near Datian Village that flows into the Qingshui-jiang, a branch of Nanpan-jiang, through an underground stream (24 17 0 59.83 00 N, 104 36 0 13.55 00 E); collected by H.F. Yang, 24 Aug. 2019 .

3.3.2 | Paratypes

SWFC 1908001-03, 190805-08, 7 ex., 84.9-157.8 mm L S; the other data same as the holotype; SWFC 1905023-28 , 6 ex., 64.6-103.7 mm L S; locality data same as the holotype, collected by H.F. Yang, 22 May 2019 ; FAQB 1905016-22 , 7 ex., 62.7-132.0 mm L S; locality data same as the holotype, collected by H.F. Yang, 22 May 2019 .

3.3.3 | Diagnosis

Pareuchiloganis posteranalis sp. nov. is distinguished from the congeners of the large-gill-opening group with long caudal peduncle by the following combination of characters (Table 1): anal-fin ray i, 3½ (v. i, 4½ in P. longicauda ); tip of maxillary barbel pointed and only reaching the lower corner of the gill opening ( v. extending beyond the lower corner of the gill opening in P. arcuatum sp. nov and P. longicauda ); anal-fin origin located about midpoint between the distance from pelvic-fin insertion to caudal-fin base ( v. about 2/5 of the distance between pelvic-fin insertion and caudal-fin base in P. arcuatum sp. nov.); adipose-fin origin located at about 2/3 of the distance between pelvic-fin insertion and anal-fin origin ( v. about 3/4 of distance between pelvic-fin insertion and anal-fin origin in P. longicauda ); the length of dorsal-fin base longer than the longest branched dorsal-fin ray ( v. shorter in P. arcuatum sp. nov. and P. salicesbarba sp. nov.); caudal-peduncle depth 27.2 – 31.3% of caudal-peduncle length (v. 14.1 – 17.8% in P. arcuatum sp. nov., 26.2 – 26.3% in P. longicauda and 18.3 – 23.0% in P. salicesbarba sp. nov.).

3.3.4 | Description

Morphometric and meristic data are in Tables 1 and 2. Dorsal-fin rays i, 5½; anal-fin rays i, 4½; pectoral-fin rays i, 14 – 15; pelvic-fin rays i, 5 – 6; branched caudal-fin rays 6 + 7; vertebra 24 + 16 = 40 (n = 2), 23 + 15 = 38 (n = 2), 23 + 16 = 39 (n = 3).

Mouth wide, inferior, transverse; anterior margin of premaxillary tooth patches exposed when mouth closed. Oral teeth coniform, embedded in skin, only tips exposed, in irregular rows. Premaxillary tooth patches broad, appear joined, with median indentation, sides not extending posteriorly. Gill-opening extending to the base of first pectoral-fin element. Post-labial groove interrupted, ending at base of inner mandibular barbel. Lower lip connected to base of maxillary barbel by skin flap, without sulcus between them.

Head depressed, rostral margin rounded when viewed dorsally. Ventral surface of the head and abdominal region moderately broad and straight. Dorsal profile rising gradually from snout tip to dorsal-fin origin, then sloping slowly ventrally to caudal-peduncle base. The caudal-peduncle slightly compressed. Oral region and anterior part of abdomen with dense papillae, density gradually decreasing posteriorly. Eye small, almost round, subcutaneous, located on dorsal surface of head. Eye closer to dorsal-most extremity of gill opening than to tip of snout. Barbels flattened, in four pairs. Nasal barbel with small flap of thin skin fringing posterior margin, not reaching anterior margin of orbital. Maxillary barbel with thin flap of skin fringing posterior margin, tip pointed, not elongating as a whisker shape and only reaching the lower corner of the gill opening. Origin of inner mandibular barbel far from midline. Outer mandibular barbel originating posterolateral of inner mandibular barbel, not close to pectoral-fin origin.

Dorsal-fin origin located at about the anterior 1/3 of the standard length (predorsal length 32.3-35.9% of L S), without spine, outer margin straight; tip of dorsal-fin rays extending beyond vertical through pelvic-fin insertion when depressed. Adipose-fin base longer, its length 35.7 – 39.7% of postdorsal distance but shorter than predorsal length; its margin almost straight and adipose-fin base deeply incised posteriorly. Anal-fin origin located midpoint between the pelvic-fin insertion and the caudal-fin base. Pectoral and pelvic fins enlarged, with broadly rounded margins; first element on each broadened, with regular striae on ventral surface. Pectoral fin not reaching pelvic-fin origin. Pelvic fin extending beyond anus. Anus located at anterior about 1/3 of the distance between the pelvic-fin insertion and the anal-fin origin, near the pelvic-fin insertion. Caudal fin truncate; skin smooth; lateral line complete and midlateral.

3.3.5 | Coloration in life

Body green-yellow on dorsal surface, milk-white on venter. Pectoral and pelvic fins yellow-brown, with light yellow distal margins. Pair of light yellow spots on post-temporal region. A yellow papilionaceous patch at dorsal-fin origin and a yellow triangular or quadrate patch at end of dorsal-fin base. Adipose fin with light yellow distal margins and a yellow stripe on its origin. Caudal fin grey-black with light yellow distal margin.

3.3.6 | Distribution

Only known from the upper Qingshui-jiang, a first-level tributary of Nanpan-jiang, belonging to the Pearl River drainage in Yunnan (Figure 4).

3.3.7 | Habitat and ecology

Pareuchiloganis posteranalis sp. nov. feeds on aquatic insects. Specimens were exclusively captured in rocky riffles where the width of the riverbed is narrow and the depth is shallow, about 3 – 5 m wide and not more than 0.2 m deep in the dry season (usually from March to the beginning of June). The water is clear and swift-flowing. The substrate is entirely rock, primarily cobbles and pebbles. On both sides of the stream are dense tall trees, shrubs and lush herbs (Figure 5b).

3.3.8 | Etymology

From the Latin poster-, meaning posterior; and -analis, meaning anal fin. Alluding to the feature that the anal-fin origin is near the caudal-fin base. Used as an adjective.