The taxonomic status and sister group relationship of the cardinalfish species Jaydia striatodes (Percomorphaceae: Apogonidae) Author Yu, Zhengsen Author Song, Na Author Han, Zhiqiang Author Gao, Tianxiang Author Shui, Bonian Author Gon, Ofer text Zootaxa 2016 4175 1 1 9 journal article 10.11646/zootaxa.4175.1.1 31b26db4-c90f-47a5-aebe-708706b68757 1175-5326 160276 CAE7CBB8-039B-4397-BEF5-4DD9BFECC422 Jaydia striatodes ( Gon 1997 ) Figure 2 a; Table 2 TABLE 2. Morphometric and meristic comparison of Jaydia striatodes and J. striata . Proportional measurements are expressed as percentage of the standard length. Jaydia striatodes Jaydia striata Beibu Gulf Holotype (paratypes)

n = 24	n = 9	n = 16
Standard length (mm)	42.2–68.4	55.3 (32.3–56.65)	38.55–70.8
Body depth	33.55–37.9	36.2 (33.0–37.5)	33.8–39.0
Body width	14.1–17.6	18.5 (17.2–19.1)	16.9–19.75
Head length	39.6–43.25	41.05 (39.8–42.7)	39.3–44.6
Snout length	6.4–7.4	7.05 (6.8–7.9)	6.0–8.0
Eye diameter	11.5–13.2	12.1 (11.3–13.4)	10.4–12.6
Interorbital width	8.1–9.2	9.5 (8.0–9.2)	7.7–9.0
Upper jaw length	19.3–21.3	20.5 (19.7–21.5)	18.5–21.4
Lower jaw length	21.8–23.8	23.7 (22.95–25.3)	22.4–24.8
Maxilla depth	5.5–6.4	6.1 (5.4–6.1)	4.8–6.1
Predorsal length	36.6–41.1	40.6 (38.3–40.6)	38.7–43.45
Prepelvic length	32.9–36.1	38.6 (37.5–40.8)	35.9–43.65
Preanal length	62.0–67.15	65.7 (63.3–66.1)	63.2–69.5
Pectoral fin length	23.2–26.0	24.7 (22.8–25.6)	21.45–26.05
Pelvic fin length	20.2–23.0	23.2 (21.8–23.2)	20.2–24.0
Length of first dorsal spine	2.7–3.6	3.1 (2.3–3.4)	2.1–3.7
Length of second dorsal spine	7.1–9.2	7.6 (6.5–8.9)	6.4–8.1
Length of fourth dorsal spine	13.4–17.7	16.3 (15.5–18.1)	14.8–18.1
Length of spine of second dorsal fin	10.8–13.9	12.1 (12.4–14.1)	11.05–13.6
Length of longest dorsal ray	22.3–25.8	26.0 (22.0–25.3)	21.3–25.1
Length of second anal spine	10.6–13.3	11.1 (11.0–13.8)	9.4–12.25
Length of longest anal ray	20.2–24.1	23.5 (21.0–23.1)	19.2–23.2
Caudal peduncle depth	15.2–17.25	15.4 (14.2–18.7)	14.3–17.3
Caudal peduncle length	22.25–25.6	22.2 (20.7–24.9)	23.1–24.8
Counts
Dorsal-fin rays	VII + I, 9	VII + I, 9	VII + I, 9
Anal-fin rays	II, 8	II, 8	II, 8
Pectoral-fin rays	15	15 (15–16)	14–16
Lateral-line scales	24+3	— (24+3)	24+3
Total gill rakers	4–5 + 12–13	5+13 (4–5 + 12–14)	3–5 + 10–13
Developed gill rakers	3 + 11–12	3+12 (2–3 + 11–12)	2–3 + 9–11
Gill rakers on ceratobranchial	9	9 (rarely 8)	8 (rarely 9)

Apogon (Jaydia) striatodes Gon 1997 : 179 , fig. 15, Thai west coast, Andaman Sea, 7°01'48"N, 99°20'24"E; holotype: USNM 213408. Jaydia striatodes ( Gon 1997 ) : Mabuchi et al . 2014 : 202 . Material examined. Jaydia striatodes : ZMNH AF0000011–17, 7: 54.1–65.2 mm SL, northwest of Hainan Island, China , 1 September 2014 ; ZMNH AF0000118–134, 17: 42.2–68.4 mm SL, near Beihai , Guangxi , China , 8 August 2015 . Comparative material. Jaydia striata : CAS 79651, 2 : 62.3–65.3 mm SL, Gulf of Thailand ; MCZ 88942, 17 : 42.4–58.85 mm SL, Persian Gulf ; SAIAB 51353, 7 : 50.3–70.8 mm SL, Tung kang, Taiwan ; USNM 68403, 69.7 mm SL, west coast of Luzon , Philippines , holotype of Apogon striatus ; USNM 213246, 21 : 30.0– 54.05 mm SL, Bay of Bengal ; USNM 213407, 6 : 38.55–43.8 mm SL, off Penang Island, Malaysia . Description. Based on Beibu Gulf specimens. Dorsal-fin rays VII + I, 9; anal-fin rays II, 8; pectoral-fin rays 15; principal caudal-fin rays 9 + 8, 15 branched, uppermost and lowermost unbranched. Lateral-line scales 24 + 3 on caudal fin base; transverse scale rows above lateral line 2; transverse scale rows below lateral line 6; median predorsal scales 4 and ctenoid. Total gill rakers 4–5 + 12–13 (usually 5+13); developed gill rakers 3 + 11–12 (usually 3 + 12); gill rakers on first ceratobranchial 9. Exposed edge of posttemporal with 6–9 weak serrations. Vertical edge of preopercle corrugate; angle of preopercle with 3–9 small, weak serrations; preopercular ridge smooth, with 3–5 small indentations at angle. Three supraneurals. One pair of uroneurals; three epurals; five free hypurals. Proportional measurements are given as the mean followed by the range in parentheses. Body depth 2.8 (2.6– 3.0) and head length 2.4 (2.3–2.5) in SL; snout length 5.65 (5.3–6.2); eye diameter 3.4 (3.15–3.6) and interorbital width 4.8 (4.2–5.2) in head length. First dorsal-fin spine 2.5 (2.1–2.9) in second dorsal-fin spine; second dorsal-fin spine 5.3 (4.6–6.0) in head length. Pectoral-fin length 4.1 (3.8–4.3) and pelvic-fin length 4.65 (4.35–5.0) in SL; pelvic-fin spine 1.7 (1.4–1.8) in pelvic-fin length. Caudal peduncle depth 1.5 (1.3–1.7) in its length, and its length 4.3 (3.9–4.5) in SL. Caudal fin slightly rounded. Ctenoid scales present on cheek, upper margin of operculum, end of isthmus, jugular, breast, predorsal, caudal fin base, anal fin base, and body; cycloid scales present on posterior third of isthmus (except for ctenoid scales behind them), pectoral fin base, breast, second dorsal fin base, and usually the first scales of each row of scales under lateral line. Lateral line scales somewhat larger than most scales in other region and the last one tapered to a point. Colour in alcohol. Body pale brown to brown; dorsal side of head darker; cheek stripe present, sometimes inconspicuous; both jaws with well-spaced melanophores, thicker at tip. Gill chamber and gills pale. Interorbital space with minute dark brown dots. Slightly bigger dark brown dots present on symphysis of lower jaw and chin. Large blackish dots on isthmus concentrated along median ridge, extending to jugular and breast. Body usually with 8–10 narrow, dark brown vertical bars; width of bars equal to or slightly greater than space between bars. First dorsal fin pale to dark brown, darker distally. Second dorsal fin pale to dark brown, usually with darker margin; membrane of second dorsal fin sometimes with faint dark stripe on proximal fourth. Both dorsal-fin bases with brown to dark brown dots. Pectoral fin and pelvic fin pale, but some melanophores usually present on tips of third and fourth pelvic-fin rays. Anal fin pale, its distal half blackish. Caudal fin pale to dark brown, usually with darker margin. Stomach and intestine blackish. Peritoneum with sparsely to moderately distributed dark dots of various sizes. Colour in life unknown. Colour of fresh specimens ( Fig. 2 a) similar to colour in alcohol, but short-lived pink hue may be present on body and fins when specimens arrive on deck. Genetic analysis. Sequences of the COI gene fragment were obtained from 15 individuals of J. striatodes , three individuals of J. striata and a single individual of J . novaeguineae . Ten haplotypes were found in the sequences of J. striatodes among which nine were unique (ZMNH AF0000012, ZMNH AF0000013, ZMNH AF0000016, ZMNH AF0000017; ZMNH AF0000118; KAUM–I. 47460, KAUM–I. 47759, KAUM–I. 80608 and KAUM–I. 80610), and the last one was shared by six individuals (ZMNH AF0000011, ZMNH AF0000014, ZMNH AF0000015; ZMNH AF0000120, ZMNH AF00000121; KAUM–I. 77592). Two haplotypes of J. striata were found in the three KAUM individuals. These sequences, together with five additional sequences of Jaydia species, as well as Apogonichthyoides niger and Nectamia fusca , downloaded from GenBank, were aligned and used for the genetic analysis. The mean genetic distance within all 15 individuals of J. striatodes was 0.3%. The genetic distances between J. striatodes and seven other Jaydia species ranged from 12.2–16.9% ( Table 3 ). TABLE 3. Mean percent distance (Kimura 2-P) between cytochrome oxidase subunit I (COI) gene of eight Jaydia species and ranges of distance within species with mean within species distance in parentheses (in bold).

Species	J. striatodes	J. striata	J. queketti	J. carinata	J. smithi	J. truncata	J. lineata	J. novaeguineae
J. striatodes	0.0–1.0 (0.3)
J. striata	12.2	0.0–0.2 (0.1)
J. queketti	15.4	14.8	—
J. carinata	14.7	16.2	12.1	0.0
J. smithi	14.6	17.4	15.3	15.6	0.0
J. truncata	14.3	16.1	15.9	16.0	9.7	0.5
J. lineata	16.9	16.6	19.6	18.3	15.0	16.3	0.0–0.7 (0.3)
J. novaeguineae	15.1	14.6	15.4	17.1	14.6	16.2	15.8	—

The phylogenetic analyses recovered identical maximum likelihood (ML), maximum parsimony (MP) and neighbor-joining (NJ) trees ( Fig. 3 ). Apogonichthyoides niger and Nectamia fusca were chosen as outgroups to root the tree. The topology retrieved eight genetically distinct Jaydia species ( Table 3 ) that grouped into four distinct clades, with J. carinata and J. queketti as the basal lineage and sister to the rest of the species. Specimens of both J. striatodes and J. striata formed well-supported monophyletic clades ( Fig. 3 ) that were distinctly separate with mean sequence divergence of 12.2% ( Table 3 ). The analyses also retrieved these two species as sister taxa in a clade that was relatively well-supported (79% bootstrap) only in the neighbour-joining tree ( Fig. 3 ). Remarks. The proportion of body width ( Table 2 ) was relatively smaller in this study because the specimens may have been compressed in the trawl. The colour pattern of the second dorsal fin varied, with a faint dark stripe on proximal fourth of the fin sometimes absent. Gon (1997) placed Jaydia striatodes at the J . lineata group which also included J. striata , and J. novaeguineae . These four species may be confused with each other because of the small differences in colour pattern and meristic characters, causing inaccurate records of their distribution ranges. The colour pattern in photographs of Apogon striatus in Shao & Chen (1993) and Jaydia lineata in Ng & Lim (2014) fits J. striatodes . Our results confirm the sister group relationship between J. striatodes and J. striata ( Fig. 3 ) proposed by Gon (1997) . The two species are very similar but can be distinguished by the number of developed gill rakers on both the upper limb (3 vs. 2, respectively; Table 2 ) and ceratobranchial (9 vs. 8; Table 2 ). In addition, J. striatodes has a blackish distal half of the anal fin, even in small fish (< 35 mm ), but in J. striata the anal fin becomes pigmented distally in large fish (> 60 mm ) ( Gon 1997 ). The former character also separates J. striatodes from all other Jaydia species. Given the great similarity between J. striatodes and J. striata ( Fig. 2 ), they may be easily confused with each other. Because past authors have not been aware that small differences in the characters mentioned above distinguish species, it could be anticipated that reports of J. striata preceding the revision of the genus by Gon (1997) may include J. striatodes . Jaydia striata was first recorded from China in the coastal water of Guangdong Province and Sanya, Xincun of Hainan Island by Cheng (1959) . Several years later, Cheng et al . (1962) reported this species with a more detailed description and a drawing. A recently published book used the name in a key (Sun & Chen 2013). Unfortunately, all these authors overlooked key characters, or did not provide enough details to identify the species they had, although the higher counts (5–6) of gill rakers on the upper limb of first gill arch recorded in Cheng et al . (1962) suggests J. striatodes . Therefore we cannot determine with certainty whether only J. striatodes is present in coastal Chinese waters. Nevertheless, the absence of J. striata in the two surveys that netted the specimens of J. striatodes used in this study, as well as other Jaydia species, lead us to consider the presence of J. striata along the southern part of the Chinese mainland coastline as questionable. Further support for this conclusion comes from the fact that in the material examined by Gon (1997) J. striata is sympatric to J. striatodes , except in Hong Kong , where only the latter species is present. FIGURE 3. Neighbour-joining tree based on the HKY + I + G model (-ln L = 2904.0452, A: C: G: T = 0.2642: 0.2966: 0.1605: 0.2787, I = 0.6360, G = 1.7440) using COI gene fragment sequence of J. striatodes , J. striata and six other Jaydia species. Numbers on the branches indicate bootstrap support for the nodes from the likelihood, parsimony and neighbor-joining analyses (from the left in that order, bootstrap values>50% from 1000 replicates are shown). The tree was rooted using Apogonichthyoides niger and Nectamia fusca as outgroups. Jaydia striata is known from the Persian Gulf, Gulf of Oman , Arabian Sea, Bay of Bengal , Malaysia , Gulf of Thailand , Indonesia, Philippines , and Taiwan ( Gon 1997 ). Jaydia striatodes has a more limited range, including the west coast of Thailand , Gulf of Thailand , Philippines , and Hong Kong ( Gon 1997 ; Satapoomin 2011 ), and possibly west coast of Taiwan and Pratas Island or Spratly Island ( Shao & Chen 1993 ; Shao et al . 2008 ). The material used in this study extends the distribution of this species further south along the coast of China’s mainland to Beibu Gulf, and to Vietnam .