Neodontobutis lani, Zhou and Li, 2022

Zhou, Mingwei, He, Anyou, Wang, Fangxin, Li, Yusen & Li, Chenhong, 2022, Neodontobutis lani, a new sleeper fish of the family Odontobutidae (Teleostei: Gobiiformes) from Guangxi, southern China, Zootaxa 5134 (1), pp. 113-124 : 115-122

Neodontobutis lani, Zhou and Li , sp. nov.

Holotype. SOU1801007-1 (25911), female, 62.4 mm standard length, obtained from a local market and presumed to be collected from the Zuojiang River , a tributary of the Xijiang River of the Pearl River basin, at Longzhou Town, Chongzuo City, Guangxi, China, collected by J.H. Lan, October 2019 ( Figure 3 ).

Paratypes. SOU1801007-3 (25913), female, 58.8 mm standard length; SOU1801007-5 (25915), male, 60.0 mm standard length. Collection locality and date same as the holotype.

Diagnosis. Neodontobutis lani can be distinguished from other Neodontobutis species by the following characteristics: anterior part of head relatively flat, with interorbital width / eye diameter =1.4–1.9 (mean=1.6), while the other Neodontobutis species possess rather compressed head and body, with mean interorbital width / eye diameter 1.0 in N. hainanensis , less than 1 in N. auarmus , 1.3 in N. macropectoralis , 1.2 in N. tonkinensis ; sensory papilla on ventral tip of lower jaw form two oblong clusters ( Figure 4c ), whereas in other Neodontobutis papillae form two single lines; several rows of transforming ctenii on posterior edge of body scales ( Figure 5a ), whereas single row of transforming ctenii on scale of the other Neodontobutis ( Figure 5b ) (Chen, Kottelat, & Wu, 2002; Iwata, 2011; Kottelat, 2001b; Vidthayanon, 1995). This species can be distinguished from Odontobutis by: presence of barbel-like projection on sensory papilla ( Figure 5c ) (absent in Odontobutis ), separated right and left gill membranes (joined in Odontobutis ) and cycloid scales on predorsal region and abdomen (ctenoid scales in Odontobutis ) ( Iwata, 2011; Vidthayanon, 1995).

Description. Morphometric and meristic data for the holotype and paratypes are presented in Table 3 respectively. Dorsal fin rays VII; I, 9; anal fin rays I, 6–7; pectoral fin rays 15, pelvic fin rays I, 5; caudal fin rays 14–15; lateral scales 34–36; transverse scales 12–15; predorsal scales 18–19; gill rakers 3+6; vertebrae 28 (13+15).

Body stout, slightly compressed posteriorly. Head large, slightly flat, interorbital distance larger than eye diameter. Lower jaw slightly longer than upper. Gill membrane separated, attached to the isthmus. Cephalic sensory canals absent. Cephalic sensory papilla pattern is illustrated in Figure 4 .

Dorsal spines nearly equal length except for the last shorter one, not reaching origin of the second dorsal fin. Origin of the anal fin slightly posterior to the origin of the second dorsal fin. Pelvic fin short, close but separated. Pectoral fins and caudal fin wide, rounded. Most body scales ctenoid with several rows of transforming ctenii on the posterior edge. Predorsal scales and part of abdominal scales cycloid.

Coloration: Head and body with dark brown mottling in live individuals. Several dark bars radiate from orbitals. Dark stripes on each side of body. A shiny, greenish blotch on upper side of operculum. A large dark blotch on base of caudal fin. Dorsal fins, anal fin and caudal fin mottled ( Figure 2 ). Preserved specimens light brown, with stripes and irregular darker blotches on each side of body. Abdominal pale, slightly yellowish ( Figure 3 ).

Phylogenetic analysis. Four individuals of Neodontobutis lani (25912, 25913, 25914, 25916) and representative species of all genera in family Odontobutidae , except for the genus Terateleoris, were used in the concatenated nuclear gene tree reconstruction. Rhyacichthys aspro (Rhyacichthyidae) was used as the outgroup according to Li (H. Li et al., 2018). For each sample, 1,027 –1,688 loci from the 4,434 targeted ones were obtained after assembling. After excluding loci with more than 50% missing data, 2,021 loci were kept for phylogenetic analysis, the length of concatenated alignment was 336,090 bp (electronic appendix). The reconstructed maximum likelihood tree is shown in Figure 6 . All genera of Odontobutidae involved in this research formed a monophyletic group. The genera Neodontobutis , Perccottus and Odontobutis were all monophyletic. Neodontobutis lani was the sister group of N. hainanensis and then formed a clade with Perccottus glenii . Aligned COI sequences can be found in electronic appendix. The COI gene tree which involved more individuals of N. lani and more N. hainanensis is shown in Figure 7 . Its topological structure is same as the concatenated nuclear gene tree at genus level except for the position of genus Microdous . All N. lani individuals formed a distinct clade apart from N. hainanensis . Both the nuclear and mitochondrial trees suggest that N. lani is an independent species and should be placed in the genus of Neodontobutis .

Distribution. Specimens of Neodontobutis lani were bought from a farmers’ market in Longzhou Town, Guangxi, which were collected by a local fisherman from tributaries of the Zuojiang River ( Figure 1 ). The detailed distribution range of N. lani requires further exploration.

Biology. According to the measurement of specimens collected in this research, maximum size of Neodontobutis lani is approximately 62.4 mm standard length. An unidentified small fish (about 25mm standard length) was found in the mouth of a non-type specimen, indicating that N. lani is carnivorous. Ovaries with mature eggs were found in a non-type specimen (48.2mm standard length), holds approximately 414 eggs, with average diameter of 1 mm.

Etymology. The new species is named after Jiahu Lan, who found the specimens. The Chinese name is Ầ氏 NJ沙dzffi.

Discussion. The genus Neodontobutis was established by Chen et al. (2002), based on N. hainanensis ( Chen et al., 2002; Iwata, 2011; Wu, 2008). This genus can be distinguished from other genera of Odontobutidae mainly by the following characters: (1) sensory papilla forming a barbel-like projection, which is the most distinctive character; (2) right and left gill membranes separate; (3) rather compressed head and body, interorbital width narrower than eye diameter; (4) predorsal scales cycloid, reaching posterior part of interorbital space; (5) sensory papilla on lower jaw arranged in two single lines ( Iwata, 2011). However, some relevant characters of N. lanii do not fit the description above: N. lani possess relatively flat head, with mean interorbital width / eye diameter = 1.6 (range = 1.4–1.9), higher than that of N. hainanensis (mean = 1.0; range = 0.8–1.1), N. auarmus (1.0 in male, 0.9 in female) ( Vidthayanon, 1995), N. macropectoralis (1.3) ( Kottelat, 2001b) and N. tonkinensis (1.2) ( Kottelat, 2001b). The mean value of interorbital width / eye diameter of N. lani was significantly higher than that of N. hainanensis (P <0.01) ( Figure 8 ), with the raw measurements can be found in electronic appendix. Moreover, several rows of transforming ctenii present on posterior edge of body scale of N. lani , while only one row of transforming ctenii present on that part of the other Neodontobutis species ( Iwata, 2011; Vidthayanon, 1995). In addition, sensory papilla on the lower jaw are arranged in two oblong clusters in N. lani , which differs from other Neodontobutis species, which have papioae in two single lines on the underside of the jaw ( Iwata, 2011). Interestingly, these characteristics of N. lani closely align with character states described for Odontobutis . Some critical external characters of genus Neodontobutis were compared to that of Perccottus and Odontobutis in table 4 ( Iwata, 2011).

Despite some similarities to Odontobutis , Neodontobutis lani was assigned to the genus Neodontobutis based on following reasons: (1) the most critical external characters, such as shape of sensory papilla (presence of barbellike projection), connection of gill membrane (not connected) and predorsal scales (cycloid, ctenoid in Odontobutis ) consistent with that of the genus Neodontobutis ; (2) molecular phylogenetic analysis shows that N. lani and N. hainanensis , the type species of the genus Neodontobutis , formed a monophyletic group with a 100 bootstrap support ( Figure 6 & 7 ). Due to inadequate taxon sampling, specimens and tissue samples of N. auarmus and other relevant species are not available for this study. The relationship of species of this genus needs further research.

Specimens of Neodontobutis lani were collected from Longzhou Town, the Zuojiang River basin, which is a tributary of the Pearl River. Neodontobutis hainanensis and O. sinensis are other Odontobutidae species distributed in the Zuojiang Basin, so the differentiation of their niches would be an interesting question. Moreover, other Neodontobutis species, N. auarmus , and N. tonkinensis and N. ngheanensis , which are tentatively placed in the genus Neodontobutis ( Iwata, 2011) , are distributed in the Indo-China Peninsula ( Khoa & Duc, 2012; Kottelat, 2001a, 2001b; Vidthayanon, 1995). Investigation on the relationship of N. lani and other Neodontobutis species may shed light on the origin, diversification and dispersal of these taxa.

According to Li et al. (2018), southern China may be the region where the family Odontobutidae originated. Indeed, southern China (Guangdong, Guangxi and Hainan), and the adjacent Indo-China Peninsula, are the diversity centers of the Odontobutidae , which is home to 7 species (belonging to 5 genera) and 6 species (belonging to 3 genera) respectively, with 2 shared genera ( Chen et al., 2002; Iwata, 2011; Khoa & Duc, 2012; Kottelat, 2001a, 2001b; Wu, 2008). Due to their small size, benthic habit and low economic importance, as well as their remote distribution, diversity of Odontobutidae in Southern China and Indo-China Peninsula is understudied. Further exploration may uncover more new species from these regions.

Figures

FIGURE 1. The sampling location of Neodontobutis lani sp.nov., indicated by the triangle.The inset shows the sampling region within the map of China.

FIGURE 2. Neodontobutis lani sp. nov., a live uncatalogued individual.

FIGURE 3. Neodontobutis lani sp. nov., SOU1801007-1, holotype, 62.4 mm standard length, Longzhou Town, Guangxi. A. dorsal, B. lateral, C. ventral views.

FIGURE 4. Patterns of main cephalic sensory papilla lines (row of spots) of Neodontobutis lani sp. nov. (SOU1801007-1, holotype) from lateral (a), dorsal (b) and ventral (c) view.

FIGURE 5. Posterior edge of scale on dorsal part of Neodontobutis lani SOU1801007-5, paratype (a) and N. hainanensis 25901 (b), ct, ctenii; tr, transforming ctenii. Sensory papilla on lower jaw of N. lani (c), p, sensory papillae.

FIGURE 6. Concatenated maximum likelihood tree of Neodontobutis lani, and species representing all genus of the Odontobutidae, except for Terateleotris, based on 2,076 single-copy nuclear loci. *SOU1801007-3 is a paratype.

FIGURE 7. Maximum likelihood tree of Neodontobutis lani, and comparative species of the Odontobutidae, based on partial sequence (~ 1500 bp) of cytochrome c oxidase subunit I (COI) gene. *SOU1801007-1 is the Holotype, SOU1801007-3 and SOU1801007-5 are the paratypes.

FIGURE 8. Comparison of the head region between Neodontobutis lani and N. hainanensis. (a) boxplot illustrates interorbital width / Eye diameter, including 12 individuals of N. lani (39.0–60.5 mm standard length) and 10 individuals of N. hainanensis (32.7–41.3 mm standard length), t value=11.171** (raw data can be found in electronic appendix). (b) Comparison of head shape of N. hainanensis (left, 41.3 mm standard length, 25901) and N. lani (right, 39.1 mm standard length, 259122).