Symphurus hongae, Lee & Munroe, 2021

Lee, Mao-Ying & Munroe, Thomas A., 2021, Unraveling cryptic diversity among shallow-water tonguefishes (Pleuronectiformes: Cynoglossidae: Symphurus) from the Indo-West Pacific region, with descriptions of five new species, Zootaxa 5039 (1), pp. 1-55 : 27-32

Symphurus hongae n. sp.

(English name: Hong’s tonguefish)

( Figs. 1 , 3 , 7–8 , 14 ; Tables 1–5, 8, 13)

Symphurus cf. microrhynchus (TW) . Lee et al. 2014: 576 (tentatively identified; genetic information used to resolve another taxonomic issue). Lee et al. 2017: 72 (tentatively identified; genetic information used to resolve another taxonomic issue).

Holotype: ASIZP0067658 , male, 53.3 mm SL, Off Nangfang-Ao, Northeastern Taiwan, M.-Y. Lee, 8 Mar 2007.

Paratypes: 35 (22 examined in detail) specimens (39.6–57.0 mm SL): ASIZP0061556 , mature female, 56.8 mm SL, off Da-Shi, Northeastern Taiwan , T.-H. Wu , 7 Dec 2000 . ASIZP0072360 , 28 (15 exam.), males, 39.6– 49.5 mm SL, off Dong-Gang, Southwestern Taiwan, M.-Y. Lee & T. A. Munroe , 4 Jul 2007 . ASIZP0072361 , immature female, 42.9 mm SL, Off Dong-Gang, Southwestern Taiwan, M.-Y. Lee & T. A. Munroe , 4 Jul 2007 . ASIZP0072362 , mature female, 45.1 mm SL, off Dong-Gang, Southwestern Taiwan, M.-Y. Lee & T. A. Munroe , 4 Jul 2007 . ASIZP0072363 , male, 44.6 mm SL, off Dong-Gang, Southwestern Taiwan, M.-Y. Lee & T. A. Munroe , 4 Jul 2007 . ASIZP0072370 , male, 57.0 mm SL, off Da-Shi , Northeastern Taiwan, M.-Y. Lee, 30 Dec 2009 . ASIZP0072371 , mature female, 50.6 mm SL, off Da-Shi , Northeastern Taiwan, M.-Y. Lee, 30 Dec 2009 . NMMB-P 3561 , mature female, 51.8 mm SL, off Kao-Hsiung , Southwestern Taiwan, 100 m, J.-H. Lee, 2 Aug 2001 .

Diagnosis. Symphurus hongae n. sp. is distinguished from all congeners by the combination of: a 1–2–2–2–2 ID pattern; 12 caudal-fin rays; 9 (3 + 6) abdominal vertebrae; 46–49 total vertebrae; 4 hypurals; 85–90 dorsal-fin rays; 71–78 anal-fin rays; 72–81 longitudinal scale rows; 28–31 transverse scale rows; 15–17 scale rows on head posterior to lower orbit; relatively wide body (BD= 27.2–30.2% of SL); PAL slightly long (22.5–27.6% of SL); short head (HL= 20.4–22.7% of SL), with its length usually shorter than its width (HW/HL= 1.07–1.16); relatively long postorbital length (POL= 71.0–74.8% of HL); upper head lobe usually larger than lower head lobe; dorsal-fin origin at vertical through posterior margin of pupil of upper eye; short predorsal length (PDL= 16.1–21.7% of HL); snout short (SNL= 11.7–15.5% of HL; SNL/ED= 0.87–1. 39), rounded to obliquely blunt anteriorly; anterior margin of upper eye usually in advance of anterior margin of lower eye; fleshy ridge well developed on posterior part of ocular-side lower jaw; with membrane covering both eyes; with continuous fleshy flap between ocular-side anterior nostril and lower part of eye; ocular-side pigmentation uniformly yellow to light brown, with dermal melanophores present at bases of anteriormost dorsal-fin rays; blind-side pigmentation uniformly white, usually with pepper-dots and dermal melanophores at bases of dorsal- and anal-fin rays; both sides of bases of anteriormost dorsal- and analfin rays with obvious dermal spots; peritoneum bluish-black.

Description. Symphurus hongae ( Fig. 7 ) is a dwarf species known from 36 specimens, the largest of which is 57.0 mm SL. Meristic characters summarized in Tables 2–5. Predominant ID pattern 1–2–2–2–2 (21/ 23 specimens). Caudal-fin rays 12. Dorsal-fin rays 85–90. Anal-fin rays 71–78. Pelvic-fin rays 4. Total vertebrae 46–49; abdominal vertebrae 9 (3 + 6). Hypurals 4. Longitudinal scale rows 72–81. Scale rows on head posterior to lower orbit 15–17. Transverse scale rows 28–31.

Proportions of morphometric features presented in Table 8. Body moderately deep; maximum depth in anterior one-third of body usually at point equal with vertical between anus and seventh anal-fin ray; body with gradual taper posterior to midpoint. Preanal length shorter than body depth. Head moderately short and wide; head width longer than head length (HW/HL= 1.07–1.16, Mean= 1.12). Upper head lobe wider than lower head lobe (UHL/LHL= 1.04–1.48, Mean= 1.22); slightly shorter than postorbital length. Lower lobe of ocular-side opercle wider than upper opercular lobe; posterior margin of lower lobe projecting slightly beyond posterior margin of upper opercular lobe. Snout relatively short, slightly rounded to obliquely blunt anteriorly; snout length usually equal to, or slightly greater than, eye diameter (SNL/ED= 0.87–1.39, Mean=1.15). Well developed dermal papillae present on blind side of snout and chin. Ocular-side anterior nostril tubular and short, usually not reaching anterior margin of lower eye when depressed posteriorly. Ocular-side posterior nostril a small, rounded tube located on snout just anterior to interorbital space. Blind-side anterior nostril tubular and relatively long, easily distinguishable from dermal papillae; blind-side posterior nostril a shorter, wider, posteriorly directed tube situated posterior to vertical at posterior margin of jaws. Jaws short and slightly arched; upper jaw length slightly longer than snout length; posterior margin of upper jaw usually extending to point between verticals through anterior margin of lower eye and anterior margin of pupil of lower eye. Ocular-side lower jaw with well-developed fleshy ridge on its posterior portion. Cheek depth relatively wide; usually equal to, or slightly longer than, snout length. Eyes moderately large (ED= 10.9–14.0% of HL), oval, contiguous; membrane covering both eyes; eye membrane connected with anterior nostril by fleshy flap of skin. Eyes usually unequal in position, with anterior margin of upper eye greatly in advance of anterior margin of lower eye. Pupillary operculum absent. Dorsal-fin origin located at point between verticals through posterior margin of upper eye and vertical slightly posterior to eye; predorsal length relatively short. Anteriormost dorsal-fin rays obviously shorter than more posterior fin rays. Scales absent on both sides of dorsal- and anal-fin rays. Pelvic fin moderately long; longest pelvic-fin ray, when extended posteriorly, usually reaching base of third to fifth analfin ray. Posteriormost pelvic-fin ray connected to anal fin by delicate membrane. Caudal fin relatively long, with several rows of ctenoid scales on its base. Scales on both sides of body numerous, strongly ctenoid.

Teeth present and recurved slightly inwards on all jaws, but better developed on blind-side jaws. Ocular-side premaxilla and dentary with single row of sharply pointed, well-developed teeth. Blind-side premaxilla with two to three rows of sharp, recurved teeth. Blind-side lower jaw with three to six rows of well-developed teeth.

Pigmentation of freshly collected specimens. Pattern of body pigmentation generally similar for both sexes at all sizes ( Fig. 7 ). Background body pigmentation of ocular side generally light-yellow to light-brown, sometimes also with several complete or incomplete crossbands; ocular surface darker along regions overlying pterygiophores of dorsal and anal fins. Melanophores in dermis also present in darker region of pterygiophores. External surface of abdominal area usually bluish-black. Background pigmentation of ocular side of head generally similar to that on body; one dark region behind eyes formed by concentration of dermal melanophores. Ocular side of snout light yellow, obvious dermal spots at bases of anterior dorsal-fin rays and on the isthmus. Outer surface of ocular-side opercle yellow to brown, with same background pigmentation as that on body and head; margin of opercle darker brown and easily distinguishable from bluish regions of opercle. Inner surface of ocular-side opercle and isthmus with small dark brown or blackish dots; ocular-side lips and chin region uniformly yellow to brown; margins of lips pigmented with small black melanophores. Ocular-side anterior nostril light-yellow to brown. Upper aspects of eyes and eye sockets light blue with darker spots; pupils bluish-black. Blind side generally white to light-yellow with bluish-black peritoneum showing through abdominal wall; pepper-dots overlying pterygiophore regions of dorsal and anal fins; some specimens with median longitudinal row of darkly pigmented melanophores along vertebral axis. Well-developed dermal melanophores also forming single longitudinal row along bases of dorsal and anal fins. Outer surface of blind-side opercle white to light-yellow, similar to that of background pigmentation. Inner surface of blind-side opercle unpigmented. Fin rays of dorsal, anal, and pelvic fins uniformly yellow to brown; basal regions of fin rays and membranes between fin rays light-yellow, with diffuse scattering of yellow to brown chromatophores covering entire fin membranes on both sides of fins. Entire dorsal and anal fins with regular pattern of streaks separating fins into darker and lighter areas. Basal margins of fin rays and associated fin membranes on blind side light-yellow to light-brown.

Pigmentation of recently preserved specimens. Similar to that of freshly caught fishes. In specimens preserved for decades, body pigmentation usually faded, except dermal spots at bases of anterior dorsal-fin rays, spots on isthmus, some pepper-dots on body, and bluish-black peritoneum, still clearly visible.

Size and sexual maturity. Twenty-three specimens range in size from 39.4–57.0 mm SL. Females are 42.9 mm SL to 56.8 mm in SL. Males (n = 18, 39.4–57.0 mm SL) attain similar sizes to those of females. One of five females (42.9 mm SL) is immature showing little elongation of the ovaries, while two others (45.1–50.6 mm SL) are nongravid, mature females with elongate ovaries, and two others (51.8, 56.8 mm SL) are gravid females.

Distribution. Symphurus hongae is known mostly from specimens taken from the fish landings at Da-Shi, Dong-Gang, and Nanfang-Ao, Taiwan ( Fig. 3 ). Specimens included in the present study were found in landings also containing an assemblage of fish species that generally live at or about depths shallower than 100 m. Based on this information, the authors suggest that S. hongae is a shallow-water species of tonguefish. More accurate information about localities, bathymetric distribution and substrata inhabited is needed for this species.

Etymology. The name hongae is in memory of Y.-S. Hong, mother of M.-Y. Lee, who died tragically in an automobile accident while this study was in progress, in recognition of her financial and moral support of his (M.-Y.) research.

Remarks. One additional sequence ( MF415269 ) isolated from an ichthyoplankton assemblage and uploaded to Genbank by D. Huang and X. Zhang from China, was identified as Symphurus microrhynchus . After updating the molecular analysis into the data set of this study, that sequence grouped with those of S. hongae . This finding presents the possibility of extending the distribution of S. hongae to southern China. However, the locality information of this sequence is mentioned only as the South China Sea. Evidence to support the distribution of this species in Chinese waters still needs robust (i.e., better documented) data, and especially saving preserved specimens for confirmation of their identity.

Comparisons. Symphurus hongae is a member of the high scale count species group of the S. microrhynchus species complex. Among the five members of this group, S. hongae is most similar to S. robustus n. sp. in that both have similar meristic and morphometric characters. In meristic features, S. hongae differs from S. robustus n. sp. in having relatively lower scale counts, including counts for head scales (15–17 vs. 16–18 in S. robustus n. sp.), transverse scales (28–31 vs. 31–34 in S. robustus n. sp.), and longitudinal scales (72–81 vs. 78–88 in S. robustus n. sp.). Among morphometric features, generally, the sizes of several morphological features of S. hongae are slightly smaller than are those for corresponding features in S. robustus n. sp. ( Fig. 8 ). Maximum size of specimens of S. hongae is 57.0 mm SL vs. 67.5 mm SL in S. robustus n. sp. Besides differences in maximum size, S. hongae can be differentiated from S. robustus n. sp. in having a thinner body (TH= 15.7–19.6% of BD vs. 22.1–30.0% of BD in S. robustus n. sp.), a relatively shorter upper jaw (UJL= 17.9–20.4% vs. 21.1–24.4% of HL), slightly shorter snout (SNL= 11.7–16.2% vs. 16.8–21.2% of HL in S. robustus n. sp.), and relatively larger eye (ED= 10.9–14.0% of HL vs. 9.6–12.0% in S. robustus n. sp.), with a larger pupil (pupil/ED= 0.45–0.68 vs. 0.35–0.46 in S. robustus n. sp.). Snout length relative to eye diameter is slightly shorter in S. hongae compared with that of S. robustus n. sp. (SNL/ED= 0.86–1.39 vs. SNL/ED 1.55–2.00 in S. robustus n. sp.), and the head is relatively longer in S. hongae (HL= 20.4–22.7% of SL vs. 19.1–21.8% in S. robustus n. sp.), as is the postorbital length (POL= 71.0–74.8% of HL in S. hongae vs. 65.8–70.2% of HL in S. robustus n. sp.), the body is relatively longer (TKL= 22.5–27.6% of SL vs. 21.6–24.7% in S. robustus n. sp.) and deeper (BD= 27.2–30.2% of SL vs. 25.5–28.3% in S. robustus n. sp.), and the head is slightly wider (HW= 22.7–25.6% of SL vs. 21.0–24.4% in S. robustus n. sp.) with a relatively shorter predorsal length (PDL= 16.1–21.7% of HL vs. 21.6–28.0% HL in S. robustus n. sp.). To more clearly reveal differences between these species, various combinations of morphometric characters useful in differentiating these two species were plotted ( Fig. 8 ).

In comparing qualitative and pigmentation features of these species, S. hongae usually features dermal spots at bases of the anteriormost ocular-side dorsal- and anal-fin rays (vs. dermal spots at ocular-side bases of the anteriormost dorsal- and anal-fin rays usually lacking in S. robustus n. sp.). In S. hongae , the upper jaw usually extends posteriorly to a point between verticals at the anterior margin of the pupil and middle of the lower eye, whereas in S. robustus n. sp., the lower jaw usually extends further to the vertical at the posterior margin of the pupil of the lower eye. The eyes of S. hongae have a different shape (oval or slightly elongate vs. round) and are positioned differently ( S. hongae with anterior margin of upper eye greatly in advance of that of lower eye vs. anterior margins of both eyes usually equal in position in S. robustus n. sp.).

Symphurus hongae is also similar to S. leptosomus n. sp., in that both species have pepper-dots on the bases of the dorsal and anal fins. In comparing meristic features between these two species, S. hongae has lower counts of head scales (15–17 vs. 20 in S. leptosomus n. sp.) and fewer transverse scales (28–31 vs. 37 in S. leptosomus n. sp.). In its morphometric features, S. hongae differs from S. leptosomus n. sp. in having a much wider body (BD= 27.2–30.2% of SL vs. 24.6% of SL in S. leptosomus n. sp.), in having the preanal length shorter than body depth (PAL/BD= 0.79–0.98 vs. 1.08 in S. leptosomus n. sp.), and by its relatively shorter head (HL= 20.4–22.7% of SL vs. 23.9% of SL in S. leptosomus n. sp.). When comparing pigmentation of these two species, S. hongae presents a uniformly light-brown background pigmentation on the ocular side (vs. ocular side dark-brown and covered with irregular speckles and blotches in S. leptosomus n. sp.).

In most meristic and morphometric characters, counts and measurements for S. hongae partially or fully overlap those of S. polylepis n. sp. Despite these similarities, S. hongae is easily distinguished from S. polylepis n. sp. in of its pigmentation. Symphurus hongae has well-developed pepper-dots and dermal melanophores on the dorsal- and anal-fin bases (vs. lacking pepper-dots and dermal melanophores lacking on the dorsal- and anal-fin bases in S. polylepis n. sp.). In meristic features, S. hongae also differs from S. polylepis n. sp. in having much lower counts of longitudinal scales (73–81 vs. 88–94 in S. polylepis n. sp.).

Among species of shallow-water tonguefishes from Indo-Pacific waters, S. hongae is also similar to S. brachycephalus . Differences between S. hongae and S. brachycephalus were highlighted above in the Comparisons section of the species account for S. brachycephalus .

Differences between S. hongae and members of the low scale count species group ( S. holothuriae , S. longirostris , and S. microrhynchus ) appear in the Comparisons sections in the species accounts for those species, respectively.

Symphurus hongae has the same ID pattern (1–2–2–2–2) and overlapping counts for dorsal-fin rays (85–90 vs. 86–92), anal-fin rays (71–78 vs. 73–80), and total vertebrae (48 vs. 48–51) as those found in S. monostigmus and S. leucochilus . However, S. hongae is readily differentiated from both S. monostigmus and S. leucochilus in having a membranous connection between the ocular-side anterior nostril and the lower eye, and it also has a fleshy ridge present on the ocular-side lower jaw (vs. both features absent in these other species). Additionally, S. hongae has fewer longitudinal scales (72–81) and fewer transverse scale rows (28–31) than is found in these other species (vs. 75–92 longitudinal and 32–38 transverse scales, respectively). Symphurus hongae differs further from S. monostigmus in having 12 (vs. 14) caudal-fin rays and 4 hypurals (vs. 5 hypurals), in lacking the pigment spot on the abdomen that features so prominently in S. monostigmus , and S. hongae has a narrower head (HW/HL= 1.07–1.16) compared with that of S. monostigmus (HW/HL= 1.38–1.42).

Figures

FIGURE 1. Diagnostic pigmentation features on blind sides of Indo-West Pacific shallow-water species of Symphurus. (A) Example of pepper-dots and dermal spots represented by S. hongae, ASIZP0072360, male, 48.0 mm SL, Dong-Gang, SW Taiwan, 04 Jul 2007. (B) Example of an unpigmented blind side represented by S. longirostris, ASIZP0072352, female (mature), 57.3 mm SL, off Kochi, Japan, 04 Apr 1994. (C) Example of median melanophores along vertebral axis as represented by S. leucochilus, holotype, USNM 408271, mature female, 58.7 mm SL, Da-Shi fish market, northeastern Taiwan, 24 Aug 2011. (D) Example of species without median series of melanophores on vertebral axis represented by S. brachycephalus, ASIZP0072364, female (mature), 49.4 mm SL, off Nan Trang, Vietnam, 19 Apr 2009.

FIGURE 3. Geographic distribution of Symphurus microrhynchus, S. holothuriae, and five new species of Indo-West Pacific shallow-water tonguefishes based on specimens examined in this study. Symbols may represent more than one locality and/or more than a single collection from each locality.

FIGURE 7. Symphurus hongae n. sp., holotype, ASIZP0067658, male, 53.3 mm SL, Off Nangfang-Ao, North eastern Taiwan. A. Ocular-side pigmentation of holotype. B. Blind-side pigmentation of holotype. C. Symphurus hongae n. sp., paratype, ASIZP0072360, male, 43.1 mm SL, Off Nangfang-Ao, Northeastern Taiwan. D. Blind-side pigmentation of paratype. Scale equals 10 mm.

FIGURE 8. Comparison of selected diagnostic features for Symphurus hongae and S. robustus. Data for these two species are presented for individuals. A. Snout length vs. Postorbital length (both as % of HL). B. Snout length vs. Length of eye diameter (both as % of HL). C. Body depth (as % of SL) vs. Body thickness (as % of BD). D. Predorsal length (as % of HL) vs. Head length (as % of SL).

FIGURE 14. Summarized maximum-likelihood (ML) tree of selected species of the genus Symphurus from the Indo-West Pacific Ocean based on partial COI gene dataset and results from the species delimitation analyses and other considerations (see materials & methods). Numbers above nodes indicate bootstrap values in percentage.Values below 70% not shown. Information of samples indicated in Table 1.