Microcanthus strigatus (Cuvier in Cuvier & Valenciennes 1831 )

Tea, Yi-Kai & Gill, Anthony C., 2020, Systematic reappraisal of the anti-equatorial fish genus Microcanthus Swainson (Teleostei: Microcanthidae), with redescription and resurrection of Microcanthus joyceae Whitley, Zootaxa 4802 (1), pp. 41-60 : 50-52

Microcanthus strigatus (Cuvier in Cuvier & Valenciennes 1831)

Stripey

Figures 1 , 4–7 ; Table 2

Chaetodon strigatus Cuvier (ex Langsdorff) in Cuvier & Valenciennes 1831: 25, pl. 170 (type locality: Nagasaki, Japan, based on manuscript of Langsdorff; holotype ZMB 8157, not examined).— Waite 1902: 189 (Pinjarrah, Western Australia; synonymy of C. strigatus Cuvier with Neochaetodon vittatum Castelnau , but not references to eastern Australian specimens).

Chaetodon (Microcanthus) strigatus .— Swainson 1839: 215 (new subgeneric assignment).

Therapaina strigatus .— Kaup 1860: 140 (new generic assignment).

? Helotosoma servus Kaup 1863: 162 (type locality: Japan; type specimens not located).

Neochaetodon vittatum Castelnau 1873: 130 (type locality, Freemantle, Western Australia; holotype MNHN A-4567, not examined).— Macleay 1881: 390 (checklist).

Microcanthus vittatus .— Whitley 1931: 112, pl. 13, fig. 3 (Western Australia; resurrection from synonymy).— Whitley 1964: 46 (checklist).

Microcanthus hawaiiensis Fowler 1941: 254 , figs 6–7 (type locality, Honolulu , Hawaiian Islands; holotype ANSP 69740 ).

Microcanthus strigatus .— Jordan & Evermann 1902: 357 (list, Formosa (= Taiwan)).— Jordan & Fowler 1902: 541 ( Japan).— Seale 1914: 73 ( Hong Kong).— Alexander 1922: 482 (Houtman Abrolhos, Western Australia).— McCulloch 1929: 248 (synonymy with Neochaetodon vittatum Castelnau 1873 ; distribution in part).— Tinker 1944: 241 (Hawaii, distribution in part; illustration).— Fraser-Brunner 1945: 463, fig. 1A (in part, Asian specimen only).—Gosline 1971: 282 (zoogeographic relationships of inshore fishes).— Springer 1982: (checklist, in part, Hawaiian distribution only).— Edgar 2000: 462 (distribution in part; colour photo, Houtman Abrolhos, Western Australia).—Randall & Lim 2000: 623 (checklist).—Hutchins 2001: 264 (checklist in part, Western Australian distribution only).—Friedlander 2004: 154 (checklist of fishes collected for aquarium fisheries).—Mundy 2005: 411 (checklist).— Hoese & Bray 2006: 1324 (checklist in part, Western Australian distribution only).— Senou et al. 2006: 474 (checklist, Sagami Sea, Japan).—Motomura et al. 2010: 133–134, fig. 259 (checklist, Kagoshima, Japan).—Parin et al. 2014: 376 (checklist, Japan and the Kuril Islands).—Kim et al. 2015: 147, fig. 1b–c (distribution records).—Kwun et al. 2017: 142 (checklist, Korea).—Nakae et al. 2018: 282 (checklist, Ryukyus Islands, Japan)

Diagnosis. Microcanthus strigatus is diagnosed in having the following combination of coloration characters: fifth body stripe inflected toward the anal fin origin at an angle of 120–150° (usually 130°); lower abdomen usually with a broken stripe, as a series of 2–5 (usually 3) spots and short dashes ( Figures 5–7 ).

Description. Dorsal-fin rays XI,16 (15–17); anal-fin rays III,14 (13–15); pectoral-fin rays 16/16 (15–17); upper procurrent caudal-fin rays 9 (8–9); lower procurrent caudal-fin rays 8 (7–9); total caudal-fin rays 32–35; diagonal rows of scales in lateral series 55 (48–57); circumpeduncular scales 28 (26–30); gill rakers 16–17; branchiostegals 7. Frequency distribution of numbers of dorsal-, anal- and pectoral-fin rays, and numbers of circumpeduncular scales and diagonal rows of scales in lateral series are presented in Table 2.

Body laterally compressed, moderately tall and roughly circular in lateral view, dorsal-fin origin to pelvic-fin origin 51.9–59.3% SL; head small 28.1–36.6% SL; snout acute, 8.3–11% SL; eye large, 11.0–14.6% SL; interorbital region naked, 8.7–11.1% SL in width.

As percentage of SL (based on examination of 66 specimens, 56.9–157.3 mm SL): predorsal length 41.7–49.0; prepelvic length 42.0–50.1; dorsal-fin origin to pelvic-fin origin 51.9–59.3; pelvic-fin origin to anal-fin origin 27.3– 35.4; dorsal-fin origin to anal-fin origin 60.8–72.9; spiny dorsal-fin base length 32.6–45.1; soft dorsal-fin base length 22.0–30.4; anal-fin origin to dorsal fin terminus 36.0–43.5; anal-fin base length 24.2–30.4; mid-dorsal fin to anal-fin origin 47.4–60.7; dorsal-fin terminus to dorsal end of caudal peduncle 7.1–13.7; anal-fin terminus to ventral end of caudal peduncle 6.3–10.1; anal-fin terminus to dorsal end of caudal peduncle 15.4–20.5; dorsal-fin terminus to ventral end of caudal peduncle 14.6–19.5; first anal-fin spine 7.0–11.5; second anal-fin spine 16.0–21.1; third anal-fin spine 8.6–14.7; pectoral-fin length 20.3–27.1; pelvic-fin length 22.0–29.7; pelvic fin spine 13.5–16.8.

Etymology. The specific epithet strigatus is the Latin for strigate, in having transverse bands or streaks of colour.

Distribution and habitat. Microcanthus strigatus is known from East Asia, Hawaii and Western Australia ( Figure 4 ). In East Asia, it occurs in southern Japan, Korea, the eastern coast of China, Taiwan and Hong Kong. Photographs in the Image Database of Fishes, Kanagawa Prefectural Museum of Natural History (KPM), indicate that the species commonly occurs in the Izu Peninsula and Sagami Bay (KPM-NR 16956), Okinawa Islands (KPM-NR 32524), Suruga Bay (KPM-NR 15245), and the Kii Peninsula (KPM-NR 84644). Microcanthus strigatus frequently inhabits rocky areas and ledges in coastal warm-temperate reefs, but can occasionally be seen in harbours, embankments, and coastal ports. Adults frequently school in large groups ( Figure 6 ). It ranges between 10 and 30 m depth, but can occur as shallow as 0.3 m (KPM-NR 4998) to as deep as 300 m (KPM-NR 11529). In Western Australia it is known from Cape Leeuwin to the Exmouth Gulf. It also occurs in Hawaii, where it has been reported from Honolulu Harbor, Haleiwa, Mokuleja, Moiliili, Kaneohe Bay, Kahala, and Molokai. Recent surveys suggest that the species now has a more restricted and localized distribution to within Lydgate State Park in Kauai.

Remarks. We tentatively consider Helotosoma servus Kaup (1863) , type species of Helotosoma Kaup (1963) , as a synonym of M. strigatus . The genus has been previously regarded as a synonym of Atypichthys (e.g., Fowler & Bean 1929; Golvan 1962; Norman 1966; Eschmeyer 1990; Fricke et al. 2019). The earliest reference to such synonymy we were able to locate is Jordan (1919), who simply stated: “said to be a synonymy of Atypichthys Gthr. ” ( Jordan 1919: 327). He did not, however, provide a justification or cite literature that provided further details. However, Atypichthys is restricted to southern Australia and the southwest Pacific, whereas the type locality for H. servus is Japan. Kaup’s description agrees well with our specimens of M. strigatus . The only noteworthy exceptions are slight differences in the orientation of the body stripes and his record of 16 anal-fin rays. However, although our specimens had only 13–15, usually 14 anal-fin rays, Randall et al. (1998) recorded 14–16 anal-fin rays for Microcanthus . It is also possible that Kaup counted the final “split-to-the-base” ray as two rays.

The holotypes of Chaetodon strigatus (ZMB 8157) and Neochaetodon vittatum (MNHN A-4567) were not examined in this review as both are dried and cannot provide comparable morphometrics. Our justification for synonymy of these nominal species is based largely on their type localities. The holotype of the C. strigatus was illustrated in black and white by Cuvier & Valenciennes (1831, pl. 170). It is unusual in showing a pair of stripes extending from the lower half of the pectoral fin. The upper of these corresponds to fifth body stripe of other specimens, and the lower presumably to the broken stripe (as a series of spots; see Figure 5 ). The lower part of the body adjacent to the anal fin is dusky, but is slightly darker immediately above the second anal-fin spine. We interpret this as the inflected part of the fifth body stripe. A colour photograph of the dried holotype of N. vittatum is provided on MNHN’s website. It lacks the broken stripe on the breast but has the characteristic fifth body stripe inflected toward the anal fin. Bauchot (1963) gave Melbourne, Victoria, as the locality for this specimen. However, this is in error, and presumably is a consequence of the confusing subtitle of the paper in which the species was described: “Supplement to the fishes of Victoria ”.

Material examined. EAST ASIA: Japan, Osumi Islands, Nakayama fishing port, KAUM-I. 68452 (96.2 mm SL); Japan, Osumi Islands , Nishinoomote fishing port, KAUM-I. 58577 (108.3 mm SL); Japan, Matsu-shima Island , KAUM-I. 110003 (128.0 mm SL); Japan, Sato , Koshiki Islands , KAUM- I. 77255 (142.4 mm SL); Japan, Amami Islands , Oshima-gun , KAUM-I. 57595 (122.6 mm SL); Japan, Shibushi Bay , KAUM-I. 30813 (131.8 mm SL); Japan, Koshiki Islands , KAUM-I.77752 (147.6 mm SL); Japan, Kumage , Yudomari Port , KAUM-I. 20063 (85.2 mm SL); Japan, Osumi Islands , Nokan , Hamatsuwaki port, KAUM-I. 60871 (94.4 mm SL); Japan, Taijiri fishing port, KAUM-I. 106014 (145.8 mm SL); Japan, Nishinoomote , KAUM-I. 80285 (148.4 mm SL); Japan, Sakinoyama , Kataura , KAUM-I. 97830 (133.0 mm SL); Japan, Sakinoyama , Kataura , KAUM- I. 97829 (126.7 mm SL); Japan, Matsushima , KAUM-I. 110002 (135.6 mm SL); Japan, Koshiki Islands , Nishi fishing port, KAUM-I. 79657 (82.8 mm SL); Japan, Chiringa Island , KAUM-I. 22548 (137.3 mm SL); Japan, Koshiki Islands , Satonishi fishing port, KAUM-I. 80597 (157.3 mm SL); Japan, Yakushima Island , Nagata , mouth of Nagata River , KAUM-I. 25201 (81.4 mm SL); Japan, Yakushima Islands , tide pool east of Yudomari port, KAUM-I. 20062 (77.7 mm SL); Japan, Osumi Islands , Makigou fishing port, KAUM-I. 66281 (120.0 mm SL); Japan, Uchinoura Bay , KAUM-I. 66684 (126.9 mm SL); Japan, Osumi Islands , Nishinoomote fishing port, KAUM-I. 98924 (104.4 mm SL); Japan, Sakinoyama , Kataura , KAUM-I. 97828 (118.3 mm SL); Japan, Osumi Islands , Hamatsuwaki port, KAUM-I. 69058 (111.4 mm SL); Japan, Shibushi Bay , KAUM-I. 30816 (134.8 mm SL); Japan, Osumi Islands , Nakayama fishing port, KAUM- I. 68451 (105.4 mm SL); Japan, Ibusuki , southwest of Kawajiri fishing port, KAUM-I. 20639 (90.1 mm SL); Japan, Osumi Islands , Makigou fishing port, KAUM-I. 66280 (102.6 mm SL); Japan, Osumi Islands , Nishinoomote fishing port, KAUM-I. 98924 (104.3 mm SL); Japan, east of Sakinoyama , Kataura , KAUM-I. 97828 (118.1 mm SL); Japan, Yakushima Island , Kurio Port , KPM-NI 24269 (73.8 mm SL); Japan, Yakushima Island , Koseda , KPM-NI 22923 (80.6 mm SL); Japan, Ryukyu Islands , Wan port, KPM-NI 26381 (109.2 mm SL); Japan, Okinawa Prefecture, Ryukyu Islands , Gushi fishing port, KPM-NI 22418 (136.0 mm SL); East China Sea , KAUM-I. 60193 (142.4 mm SL); Hong Kong, ANSP 76638 (106.0 mm SL); Hong Kong, ANSP 76867 (96.2 mm SL); China, Fujian province, Pingtang , ANSP 76579 (80.5 mm SL); WESTERN AUSTRALIA: Rottnest Island , WAM P.4945-001 (2: 80.5–81.3 mm SL); Rottnest Island , WAM P.33193-001 (2: 79.3–81.5 mm SL); Rottnest Island , WAM P.5601-001 (2: 98.2–113.0 mm SL); Rottnest Island , WAM P.5632-001 (114.0 mm SL); Rottnest Island , WAM P.4946-001 (56.9 mm SL); Woodman Point , WAM P.25225-003 (2: 70.9–73.5 mm SL); Shark Bay , WAM P.5382-001 (2: 76.7–77.0 mm SL); Shark Bay , WAM P.5868-001 (79.7 mm SL); Shark Bay , WAM P.4436-001 (77.6 mm SL); HAWAII: Oahu , Laie , ANSP, 86808 (84.1 mm SL); Oahu , Moiliili , BPBM 4202 (71.4 mm SL); Oahu , Kaneohe Bay , BPBM 9794 (2: 106.0– 109.3 mm SL); Oahu , Haleiwa River , BPBM 15432 (2: 101.1–109.3 mm SL); Oahu , Honolulu , BPBM 4201 (2: 98.5–154.0 mm SL); Oahu , Honolulu , ANSP 69742 (148.5 mm SL; paratype of M. hawaiiensis ); Oahu, Honolulu, ANSP 88443 (103.1 mm SL); Oahu, Honolulu, ANSP 86807 (90.5 mm SL); Molokai, northwest side of island, BPBM 23814 (2: 91.6–103.8 mm SL); Molokai, northwest side of island, BPBM 24134 (116.9 mm SL) .

Figures

FIGURE 1. X-radiograph of Microcanthus strigatus, KPM-NI 24269, 73.8 mm SL, Yakushima Island, Japan. Radiograph by A. Hay.

FIGURE 4. Phylogenetic relationships and population structure for Microcanthus. A) Tree inferred using maximum likelihood and Bayesian inference based on mitochondrial 16S, COI and control region. Numbers at nodes indicate posterior probabilities inferred using Bayesian analysis in MrBayes and likelihood bootstrap support from a maximum-likelihood analysis in RAxML. Atypichthys (not shown) was used as the outgroup. B) Geographic distribution of Microcanthus. Geographic distributions of Microcanthus are colour coded as follow: Blue—East Asia (M. strigatus); Yellow—Hawaii (M. strigatus); Pink—Western Australia (M. strigatus); Purple—Southwest Pacific (M. joyceae). C) Bayesian clustering plots for 82 individuals of Microcanthus from populations of M. strigatus from East Asia, Hawaii and Western Australia, and M. joyceae from the southwest Pacific. The most likely number of partitions was K = 3 (LnP = -184055). The second most likely number of partitions was K = 4 (LnP = -187956). For discussion of phylogenetic relationships and population genetics of Microcanthus, see Tea et al. (2019).

FIGURE 5. Microcanthus strigatus, KAUM-I. 98924, 104.3 mm SL, Tanegashima Island, Osumi Islands, Kagoshima Prefecture, Japan. Note the broken stripe (as a series of spots) on the lower abdomen (black arrow) and the inflected anal-fin stripe (white arrow). Photograph by Y.K. Tea.

FIGURE 6. A school of Microcanthus strigatus, underwater photograh at Yakushima, Japan. Note the characteristic inflected anal-fin stripe and series of spots on the lower abdomen. Photograph by S. Harazaki.

FIGURE 7. Microcanthus strigatus, in situ photograph from Omeo Wreck, Coogee, Western Australia. The fish species in the background is the pempherid Pempheris klunzingeri. Photograph by R. Turnbull.