Synagrops atrumoris, Mediodia & Lin & Ho & Přikryl, 2024

Mediodia, Dominique P., Lin, Chia-Hao Chang Chien-Hsiang, Ho, Hsuan-Ching & Přikryl, Tomáš, 2024, Positive association between PTN polymorphisms and schizophrenia in Northeast Chinese Han population., Zoological Studies 63 (20), pp. 141-149 : 4-7

Order Acropomatiformes Gill, 1893 Family Synagropidae Smith, 1961 Genus Synagrops Günther, 1887

Synagrops atrumoris sp. nov. Mediodia & Lin ( Figs. 2–9 ) urn:lsid:zoobank.org:act:EB93B24D-AC2A-48EB-ACDC-568526CA7218

English name : Dongsha Blackmouth splitfin; Chinese name : 東沙黑口尖牙鱸.

H o l o t y p e: ASIZP0081729 (173.6 mm SL) collected in Dongsha Island, Taiwan, South China Sea (coordinates 18°56'N, 112°57'E).

Paratypes: Twenty-nine specimens with 124.6–179.6 mm SL collected from near the holotype locality: ASIZP0081726 (5 specimens, 155.7–178.7), ASIZP0081726 (6 specimens, 154.2–171.1), ASIZP0081728 (10 specimens, 136.3–179.6), ASIZP0081730 (8 specimens, 124.6–170.4), and ASIZP0081731 (1 specimen, 137.8).

Diagnosis: A species of Synagrops differs from its congeners with the following combinations of characters: black mouth cavity covering the lower portion of the tongue in larger individuals (> 100 mm SL), basioccipital fossae are posteriorly enlarged and complex, triangular otolith with a pointed anterior rim and vertical posterior rim.

Description: Morphometric and meristic values are provided in table 1. Data presented are for the holotype and range of paratypes in parenthesis. Body elongated, less compressed laterally. Head massive and naked with a prominent W-shaped cranial crest. Mouth terminal and large. Eyes large with small black pigments circulating the margin. Snout short. Anus near the pelvic fin base. Dorsal, pelvic, and anal fins with prominent dark spots at the tip. The 1st and 2nd dorsal fins are separated. First dorsal spine in the 1st dorsal fin shortest, 3rd fin longest. The third fin ray in the 2nd dorsal fin longest. First dorsal-fin rays IX; 2nd dorsal fin rays I, 9 (I, 8–9). Anal fin near the posterior part of the body. First anal spine shorter than 2nd anal spine. Third anal fin ray longest. The pterygiophore of the proximal-middle radial 1st anal fin broad and bent towards the 1st haemal spine. Anal-fin rays II, 7. Pectoral fin not reaching anus. Pectoral-fin rays i15–15i (i15–16i). Non-serrated pelvic spine. Pelvic-fin rays I, 5. Caudal fin forked. Principal caudal-fin rays 9 + 8 (8–9 + 8–9), complete caudal fin formula including procurrent rays is 8, i, 9+8, i, 8. Small rows (2–5) of denticles on the ectopterygoid. The lateral side of the lower jaw with 2 (2–3, n = 8) strong canines and 4 (4–5, n = 8) small canines protruding in the upper jaw. Small serrations in preopercle with 2–3 rounded small ridges at the lower rear margin. Swimbladder reaching cranium. Gills with 2 (2–3) short rakers at the upper arch and 10 (8–10) long at the lower arch; rakers dark brown to black; gill filaments reddish pink. Predorsal formula 0/0/0+2/. Vertebrae count 25 (10 abdominal and 15 caudal). Scales cycloid and easily shed. Lateral scales 30 (29–32).

Coloration: Body color black-to-gray with a metallic sheen in the entire body, pale-cream color without scales. Metallic color in the ventral part of the body.

Osteological notes: Skeletal characters of the new species were studied in all skeleton parts. It generally resembles that of S. japonicus . The only significant differences were identified in the otic region of the skull and the immediately adjacent portion of the vertebral column. Due to that reason, only the neurocranium (especially its otic portion) and the anterior-most part of the vertebral column are emphasized in the study. The neurocranium in the dorsal view is almost squarish in shape, somehow broader posteriorly. The skull roof is ornamented by a system of anteriorly diverging ridges and large openings, creating a prominent W-shaped cranial crest. The dorsal part of the otic section is extensively covered by epaxial musculature. The dorsal margin of the neurocranium in lateral view is convex, while the ventral margin is more or less straight (the only exception is the ventrally prominent vomerine section). The neurocranium in the lateral view is significantly lower and shorter in the ethmoid region than in the otic region. The orbit is large, approximately 40% of the length of the neurocranium. The supraoccipital crest is short but relatively deep. The openings of the myodome are enlarged dorsally, and the prootic participate in the construction of the myodome margins just by small and short sections in the antero-lateral corners. The basioccipital fossae are emarginated by the exoccipital laterally (the ventral margin of this skeletal element is swollen), the prootic antero-laterally, and the basioccipital anteriorly and medially. The medial section of the basioccipital protrudes at the caudal part to the lateral spurs and is in contact with the medial side of the exoccipital. The posterior part of the basioccipital fossae is shifted posteriorly, and its margin is defined by ventro-laterally bony outgrowths of the 1st vertebra. The whole complex of the basioccipital fossae in S. atrumoris sp. nov. is antero-posteriorly segmented, and the complete construction extends to the 1st vertebra.

Otolith: The otolith is triangular with a pointed anterior rim and a vertical posterior rim. The dorsal and ventral rims are oblique anteriorly, interrupted by distinctive angles forming the highest part of the otolith. Beyond these angles, both rims exhibit a relatively horizontal and flat profile towards the pronounced angle. Notably, there is a pronounced angle situated at both the postero-dorsal and postero-ventral corners. However, the postero-ventral angle appears more prominent and may extend further towards the posterior. The otoliths are thin. The outer face is concave, and the inner face is convex. The dorsal margin is irregular with small crenulations, specifically on the anterodorsal margin. The horizontal part of the ventral margin and the posterior margin are crenate. The sulcus is deep and well-differentiated into the ostium and cauda. A funnel-like ostium is widely open antero-dorsally. There is a large oblong ostial colliculum situated below the longitudinal midline of the ostium. The cauda is deepened slightly, directing upward before curving strongly (about 90°) at the most posterior region, with its tip directing antero-ventrally. It is narrowing towards the neck. Cristae are well-developed. A notch is present and the antirostrum is small.

Etymology: The specific name is a combination of the Latin “ atrum ”, meaning black, and “ oris ”, meaning mouth, in relation to its diagnostic black mouth floor.

Distribution: Currently known from the Dongsha Islands, Taiwan, and the South China Sea. Possibly from the south of Scott Reefs, Western Australia (see below).

Size: The largest sample examined in this study is 206.88 mm SL.

Phylogenetic analyses: Out of 68 COI sequences used in this study from 3 taxa, we have detected 46 haplotypes and 506 aligned base pairs, which contained 169 variable sites and 102 parsimony informative sites. The NJ tree revealed there are two groups (Group 1 and Group 2) with high supports (bootstrapping value> 90) ( Fig. 9 ), and the average pairwise genetic distance (K2P) between these two groups is 0.06. Group 1 includes S. bellus and nearly all S. japonicus specimens, but the two species nest each other within the group. The average K2P distance within the group is 0.01. Group 2 contains all specimens belong to S. atrumoris sp. nov. and three sequences of S. japonicus (74–128 mm SL) from south of Scott Reefs, Western Australia (JN313203– JN313205), and the average K2P distance within the group is 0.01.

Figures

Fig. 2. Synagrops atrumoris sp. nov. A, ASIZP0081729, holotype, 173.60 mm SL, fresh and B, radiograph. Scale bar = 10 mm.

Fig. 3. Synagrops atrumoris sp. nov., A–D, paratypes, fresh, A, ASIZP0081728, 159.0 mm SL; B, ASIZP0081728, 130.3 mm SL; C, ASIZP0081728, 176.8 mm SL; D, ASIZP0081728, 137.6 mm SL. Synagrops japonicus (Döderlein, 1883), E–F, non-types, fresh, E, ASIZP0081733, 168.6 mm SL; F, ASIZP0081733, 156.5 mm SL. Synagrops bellus (Goode and Bean, 1896) G–H, non-types, preserved, G, MCZ49930 172 mm SL; H, MCZ49930 213 mm SL. Scale bar = 10 mm.

Fig. 4. Mouth color of Synagrops atrumoris sp. nov., paratype, ASIZP0081731, 165.5 mm SL, Synagrops japonicus (Döderlein, 1883), non-type, ASIZP0081731, 152.8 mm SL, and Synagrops bellus (Goode and Bean, 1896), non-type, MCZ49930, 172.98 mm SL. A, fresh and B, preserved in alcohol. Not to scale.

Fig. 5. Neurocrania of A–B, Synagrops atrumoris sp. nov., non-type, CHLP2000314, 178.9 mm SL, and C–D, Synagrops japonicus (Döderlein, 1883), non-type, CHLP2000309, 184.1 mm SL showing ventral (A and C), and lateral views (B and D) emphasizing the prootic, exoccipital, basioccipital, 1st vertebra, and 2nd vertebra. The actual images are presented in figure S1. Scale bar = 10 mm.

Fig. 6. Radiographs showing the ventral view of the neurocrania of A, Synagrops atrumoris sp. nov., paratype, ASIZP0081728, 152.54 mm SL, B, Synagrops japonicus (Döderlein, 1883), non-type, ASIZP0081733, 147.51 mm SL, and C, Synagrops bellus (Goode and Bean, 1896), non-type, MCZ49930, 172.98 mm SL. Not to scale.

Fig. 7. Prootic (A–D), exoccipital (E–H), and basioccipital (I–L) of Synagrops atrumoris sp. nov., non-type, CHLP2000314, 178.9 mm SL, and Synagrops japonicus (Döderlein, 1883), non-type, CHLP2000310, 174.2 mm SL. The actual images are presented in figure S2. Scale bars = 5 mm.

Fig. 8. Otoliths (right sagitta) of Synagrops from Taiwan. A–E, Synagrops atrumoris sp. nov., paratypes; A, CHLOL24862, 178.76 mm SL; B, CHLOL24863, 136.34.11 mm SL, C, CHLOL24864, 186.12 mm SL, D, CHLOL24865, 119.29 mm SL, E, holotype, CHLOL24861, 173.60 mm SL, F–G, Synagrops japonicus (Döderlein, 1883), non-types, F, CHLOL24866, 152.54 mm SL, G, CHLOL24867, 114.35 mm SL, 1, ventral views, 2, dorsal views. Scale bar = 1 mm.

Fig. 9. Neighbor-joining tree based on the cytochrome oxidase subunit I (COI) gene showing the relationships of Synagrops atrumoris sp. nov., Synagrops japonicus (Döderlein, 1883), and Synagrops bellus (Goode and Bean, 1896). Haplotype names (AH, S. atrumoris sp. nov., JH, S. japonicus, BH, S. bellus, and AJH, haplotype of S. atrumoris sp. nov. and S. japonicus) are presented in table 2. Support values> 70 are presented.