Iago garricki Fourmanoir & Rivaton, 1979

Ng, Shing-Lai, Ho, Hsuan-Ching, Liu, Kwang-Ming & Joung, Shoou-Jeng, 2022, Redescription of the longnose houndshark Iago garricki (Carcharhiniformes Triakidae), based on specimens recently collected from the South China Sea, Zootaxa 5189 (1), pp. 67-77 : 68-76

Iago garricki Fourmanoir & Rivaton, 1979

Figs. 1–5 ; Table 1

Iago garricki Fourmanoir & Rivaton, 1979: 434 , figs. 22 (Efate, Vanuatu, western-central Pacific Ocean). Compagno 1984:

395–396; Last & Stevens 1994: 212–213; White et al. 2006: 190–191; White et al. 2018: 120–121 Ebert et al. 2021: 475. Materials examined. Holotype. MNHN-IC-1978-0694, 620 mm TL, mature female, 17°05’S; 167°05’E, Vanuatu, Coral Sea, 350 m depth, 1978. Non-types. MHNH-IC- 1997-3572, 508 mm TL, adult male, 16°65’S; 168°02’E, Vanuatu, western-central Pacific Ocean, 541–577 m depth, 1994. MHNH-IC- 2008-1304, 244 mm TL, juvenile male, 15°69’S; 167°01’E, Vanuatu, western-central Pacific Ocean, 509–659 m depth, 2006. MHNH-IC- 2008-1346, 250 mm TL, juvenile female, 15°68’S; 167°01’E, Vanuatu, western-central Pacific Ocean, 503–600 m depth, 2006. ASIZP 81240, 280 mm TL, juvenile female, ca. 19°N, 114°E, off western Dongsha Atoll, South China Sea, ca. 300 m depth, bottom trawl, 19 February 2021, coll. Y.- T. Lee. ASIZP 81241, 435 mm TL, adult male, NMMB-P 36356, 495 mm TL, adult male, NMMB-P 36357, 500 mm TL, adult male, ASIZP 81242, 515 mm TL, adult male, ca. 19°N, 114°E, off western Dongsha Atoll, South China Sea, ca. 300 m depth, bottom trawl, 19 February 2021, coll. C.-H. Lin.

Diagnosis. A species of Iago with a long, narrow snout, preoral length 35.1% (34.9–38.7%) head length; eye large, length 18.5% (17.0–24.1%) head length; gill slit rather short, the first gill slit height 47.8% (31.4–51.6%) eye length; anterolateral teeth straight to slightly oblique, blade-like, with 1–3 broad, smooth distal cusplets ( Fig. 4c ); first dorsal-fin origin not reaching a vertical line through pectoral-fin base; caudal-fin ventral lobe moderately developed in adults; body color generally grey, with faint dark edges on dorsal-fin apexes, more prominent in juveniles ( Fig. 2 ).

Description. Morphometric data are provided in Table 1 . The following data are provided for the holotype, followed by the range of measured or counted non-types in parentheses.

TABLE 1. (Continued)

TABLE 1. (Continued)

Body subtriangular in cross-section at first dorsal-fin base; pectoral–pelvic space 19.0% (18.1–24.1%) TL, pelvic–caudal space 28.8% (23.9–28.1%) TL; second dorsal-fin origin to anal-fin origin 88.4% (66.7–99.1%) analfin base length; anal–caudal space 20.5% (16.1–18.2%) preanal length; a distinct hump present at dorsal profile above pectoral fins in holotype (hump absent in other non-types); interdorsal and postdorsal ridge absent. Caudal peduncle long, slender, elliptical in cross-section, tapering towards caudal fin, without lateral keels; height 128% (129–252%) width at upper caudal-fin origin, 25.0% (17.5–38.2%) dorsal–caudal space. Precaudal pits absent.

Head length 108% (90.5–112%) pectoral–pelvic space; head slightly depressed, rather flat in lateral view, slightly convex over eye, slightly concave on preorbital snout, post-oral head straight. Snout tip narrowly rounded in dorsoventral view; moderately pointed in lateral view, narrowly rounded in ventral view in both juveniles and adults ( Fig. 3 ); preoral snout 35.1% (34.9–38.7%) head length. Eyes elliptical, large, eye length 18.5% (17.0–24.1%) head length; positioned laterally on head; fleshy subocular ridges vestigial; anterior notch absent, posterior notch not prominent; nictitating lower eyelids external; subocular pouches shallow, scaled with secondary lower eyelids. Spiracles very small, bean-shaped, positioned below middle of eye.

Gill slits rather short; first and second gill slits tallest, fifth shortest; height of the fifth 74.8% (56.8–87.8%) height of the first; height of the first 8.8% (7.6–9.2%) head, 47.8% (31.4–51.6%) eye length. Upper margin of gill slits barely reaching a horizontal line through lower margins of eyes.

Nostrils moderately large, with circular incurrent apertures; well separated from mouth; width 57.8% (45.5– 79.5%) internarial space, 43.9% (33.3–61.5%) eye length, 91.9% (80.0–137%) in first gill slit height; excurrent apertures small, bean-shaped; anterior nasal flaps broadly triangular, large; mesonarial flaps and posterior nasal flaps poorly developed.

Mouth considerably arched (less arched in juveniles), width 36.9% (25.7–41.6%) head length; length 48.5% (37.1–65.5%) width; tongue very large, flat, blunted apically, covering almost the entire floor; buccal papillae absent, buccopharyngeal denticles present on anterior part of the palate to the level of spiracle. Labial furrows moderately elongate; lower furrows distinctly shorter than upper furrows, length 71.6% (39.2–91.9%) length of upper furrows; length of upper furrows 73.6% (58.7–91.3%) mouth length; anterior tip of upper furrows anterior to vertical mid-orbit, reaching about level of lower jaw symphysis.

Teeth including symphysials in 50/44 (43–54/36–41) rows, 2–4 series functional. Tooth formula of upper jaw 24+3+23 (20–25+1–4+20–25), lower jaw 22+1+21 (18–20+1–2+17–20). Teeth not arranged in diagonal files, no toothless spaces at symphysis. Tooth size similar between jaws, but different in shape between and along jaws ( Fig. 4 ). Symphyseal teeth in upper jaw only slightly smaller than anterolateral teeth, with erect, slender, symmetrical cusp, notched medially and laterally, medial and lateral margins smooth, moderately notched ( Fig. 4A ). Anterolateral teeth in upper jaw with somewhat broad, straight to slightly oblique, blade-like cusps; mesial margins weakly convex basally, straight distally; 1–3 broad, smooth distal cusplets present; both margins and basal cusplets without serrations ( Fig. 4C ). Lateral teeth in upper jaw becoming more oblique gradually towards posterolateral side. Symphyseal teeth size in lower jaw same as anterolateral teeth ( Fig. 4B ). Anterolateral teeth shape in lower jaw similar to upper jaw, but with straight cusps, becoming somewhat oblique gradually towards posterolateral side ( Fig. 4D ).

Lateral trunk denticles below first dorsal fin small and imbricated; crowns narrowly pointed distally; apices narrowly pointed; crowns with 2–4 longitudinal ridges; no prominent reticulations on crown; crown length much longer than width ( Fig. 5 ).

Pectoral fins triangular; subequal or slightly larger than first dorsal fin; anterior margin straight; posterior margin 78.6% (58.9–79.6%) anterior margin; base narrow, its length 30.4% (29.6–41.2%) anterior margin; apex broadly rounded; posterior margin moderately concave; free rear tips broadly round; inner margins straight; origin under fourth gill opening to midway between fourth and fifth gill openings. Pelvic fins very narrowly subtriangular; anterior margin somewhat convex, 33.8% (36.2–42.3%) pectoral-fin anterior margin; apex very broadly rounded; posterior margin concave; free rear tip acutely pointed; inner margins straight. Claspers of four adult males long, slender and narrow-based; length (56.8–82.0%) pelvic-anal space; apex narrowly rounded, extending to near midway of pelvic-anal space.

First dorsal fin falcate; anterior margin concave basally, slightly convex distally; apex narrowly rounded (broadly rounded in juveniles); posterior margin deeply concave to the free rear tip; free rear tip narrowly pointed; inner margin straight; origin reaching a vertical line through anterior half of middle pectoral-fin inner margin, before pectoral-fin base; free rear tip slightly posterior to midway between pectoral-fin base and pelvic fin origin; insertion about opposite to pectoral fin apex; first dorsal-fin base 29.7% (28.1–40.5%) interdorsal space, 71.1% (54.6–95.2%) dorsal–caudal-fin space; fin height 70.8% (68.6–93.5%) base length; inner margin 39.4% (47.4–84.3%) height, 27.9% (37.5–68.7%) base length.

Second dorsal fin slightly falcate, smaller than the first dorsal fin, height 74.5% (48.9–86.1%) first dorsal-fin height, base length 76.4% (56.6–107%) first dorsal-fin base length; anterior margin slightly concave basally, straight distally; apex narrowly rounded (broadly rounded in juveniles); posterior margin upright, deeply concave before the free rear tip; free rear tip pointed, terminating barely anterior to anal-fin free rear tip; inner margin straight; origin slightly anterior to anal-fin origin; insertion well posterior to fin apex, opposite to anal-fin insertion; second dorsalfin base length 54.4% (40.8–81.0%) dorsal–caudal space; height 69.1% (57.0–77.5%) base length; inner margin 77.2% (35.8–67.9%) height, 53.4% (26.6–39.9%) base length.

Anal fin low and weakly falcate, about half of second dorsal fin; height 69.1% (35.8–62.3%) second dorsalfin height, base length 82.6% (62.4–96.1%) second dorsal-fin base length; anterior margin weakly convex; apex broadly rounded; posterior margin concave; free rear tip short, narrowly pointed, well separated from lower caudalfin origin; inner margin straight; insertion nearly opposite to fin apex, just posterior to second dorsal-fin insertion; anal-fin base length 40.8% (40.6–61.4%) anal–caudal space; fin height 57.8% (27.7–69.6%) base length; inner margin 78.8% (39.7–93.3%) height, 45.6% (27.7–53.8%) base length; preanal ridges and grooves absent.

Caudal fin asymmetrical, upper lobe moderately narrow; terminal lobe enlarged, ventral lobe narrow, moderately developed in adults, weakly developed in juveniles; dorsal margin moderately long, 28.8% (27.6–33.3%) precaudal length, nearly straight to weakly convex, slightly concave above terminal lobe, without lateral undulations; preventral margin slightly convex, 73.3% (59.2–83.3%) in dorsal–caudal space, apex broadly rounded; lower postventral margin very short, moderately concave; upper postventral margin slightly concave anteriorly, slightly convex near subterminal notch; subterminal notch very short; subterminal margin weakly convex, terminal margin nearly straight to slightly convex; subterminal margin length 67.1% (71.8–88.5%) terminal margin length; terminal lobe margins straight to slightly concave; terminal lobe length 75.7% (63.6–73.8%) dorsal-caudal margin.

Total vertebral centra 156 (149–157), precaudal centra 98 (94–102), monospondylous centra 41 (39–42), diplospondylous precaudal centra 57 (53–61).

Coloration. When fresh, grey to brownish grey dorsally, gradually becoming paler ventrally. In adults, dorsal fins dusky, with narrow dark edges on apexes; dark blotches on dorsal-fin apexes present in juveniles. Caudal fin generally greyish brown with narrow white margins on terminal and lower lobe; weak black edges on dorsal margin, more prominent in juveniles; anal fin dusky, with inconspicuous white margin on apex; pectoral fins mostly dusky, with narrow dark edges on anterior margins; posterior margins somewhat whitish; pelvic fins uniformly dusky, without any dark edges; ventral surface completely white. In preservative, eyes white, others very similar to fresh color.

Size. To about 750 mm TL ( Fourmanoir & Rivaton 1979). Length-at-birth is estimated approximately 280 mm TL, given the presence of umbilical scar in the small specimens (ASIZP 81240).

Distribution. Known from Indo-Pacific, from the South China Sea to northwestern and northeastern Australia, including Indonesia, the Philippines, Papua New Guinea and Vanuatu. Bathymetric range 250– 659 m.The occurrence of I. garricki from the South China Sea represents the northernmost distributional record (ca. 700 km northward extension from the Philippines).

Ecology. Stomach contents of one specimen (ASIZP 81242) and six adult males (470–500 mm TL, not retained) included small Macrouridae ( Hymenocephalus sp. , Nezumia sp. , Ventrifossa spp. ), crustaceans (Penaeoidea, Munidae) and cephalopods. This species is assumed benthic and has a generalist diet.

Remarks. Fourmanoir & Rivaton (1979) described I. garricki based on five specimens. One of the specimens was designated as holotype and preserved in MHNH, but the whereabouts of other specimens is unknown. A search for those paratypes in MHNH by HCH was unsuccessful.

Iago garricki can be distinguished from its only congener, I. omanensis , by having a shorter head, its length 20.2–22.2% TL (vs. 23.0–27.5% TL) and longer upper labial furrow (2.2–3.4% TL, vs. 1.1–2.0% TL). The two species can further be separated by the preoral length, which is slightly longer in I. garricki (7.2–8.3% TL, vs. 5.7–7.6% TL in I. omanensis ), although the values slightly overlap. The shape of lateral teeth is also unique in I. garricki , in which small cusplets on lateral side present basally (vs. cusplets absent in I. omanensis ). Vertebral count also separates the two species, I. garricki has more diplospondylous centra (53–61, vs. 45–52 in I. omanensis ), more precaudal centra (94–102, vs. 81–91), and more total centra (149–157, vs. 129–147) (data taken from Compagno & Springer, 1971).

According to Ebert et al. (2021), I. garricki is further distinguished from I. omanensis by having much smaller gill slits, their length smaller than eye length (vs. longer than eye length in I. omanensis ), and the first dorsal-fin origin over pectoral-fin inner margin (vs. situated well over the pectoral-fin base). Geographically, the distribution of I. garricki does not overlap with that of I. omanensis , the former is restricted to the western Pacific and the southeastern Indian Ocean, while the latter occurs in the northern Indian Ocean, including the Red Sea.

Although having similar morphometrics, juveniles of I. garricki generally process broader dorsal-fin tips, a less arched mouth, and a poorly developed caudal-fin ventral lobe when compared to adults. Juveniles have large dark blotches on the dorsal fins (vs. only narrow dark margins present on fin edges in adults), and prominent black edges on caudal fin dorsal margin (vs. poorly-defined black edges present in adults).

Difference in morphometrics and counts between the holotype and the other non-types are observed. For example, the holotype has three more lower jaw teeth than the other non-types. Some morphometrics (e.g. first dorsal-fin height, caudal-fin proportions) of the holotype are also not within the range of the non-types. Furthermore, the holotype processes a distinct hump on the dorsal profile above pectoral fins, but it was not observed in other examined specimens. The hump is not likely a result of preservation condition, as it already existed when fresh ( Fourmanoir & Rivaton 1979: fig. 22a). We assume the difference as sexual dimorphism, mature female processes a humped dorsal profile above pectoral fins, and may have difference in morphometrics and counts. Since only one mature female (the holotype) was examined, however, it warrants further investigation given the smaller size of other examined male specimens comparing to the holotype.

Figures

FIGURE 1. Holotype of Iago garricki. MNHN-IC-1978-0694, 599 mm TL, adult female. Preserved condition.

FIGURE 2. Fresh coloration (previously frozen) of Iago garricki specimens collected from the South China Sea. A. ASIZP 81240, 280 mm TL, juvenile female. B. ASIZP 81241, 435 mm TL, adult male. C. NMMB-P36356, 495 mm TL, adult male. D. NMMB-P36357, 500 mm TL, adult male E. ASIZP 81242, 515 mm TL, adult male. Scale bar = 10 cm.

FIGURE 3. Ventral views of head. A. ASIZP 81240, 280 mm TL, juvenile female. B. ASIZP 81242, 515 mm TL, adult male.

FIGURE 4. Teeth ofASIZP 81242, 515 mmTL, adult male.A. upper jaw symphyseal teeth. B. lower jaw symphyseal teeth. C. left upper jaw lateral teeth. D. left lower jaw lateral teeth.

FIGURE 5. Dermal denticles from below first dorsal-fin base of ASIZP 81242, 515 mm TL, adult male.

Tables

TABLE 1 Morphometric data of Iago garricki and I. omanensis from Compagno & Springer (1971). *: Counts were not

		I. garricki		I. omanensis
	Holotype	Non-types		Non-types
Total length (mm)	599	244–515 (n=8)		224–582 (n=16)
Measurements (% TL)		Mean (range)	SD	Range
Pre-second dorsal length	58.8	59.0 (55.6–61.4)	1.9	56.8–59.9
Pre-first dorsal length	24.2	26.3 (25.0–28.2)	1.0	24.0–29.5
Head length	20.5	21.4 (20.2–22.2)	0.6	23.0–27.5
Prebranchial length	15.9	17.3 (16.7–17.8)	0.3	16.2–20.0
Prespiracular length	12.1	13.0 (12.2–14.3)	0.6	-
Preorbital length	7.6	7.7 (6.9–8.4)	0.5	-
Prepectoral length	19.5	21.0 (19.2–22.8)	1.4	21.2–25.9
Prepelvic length	41.7	44.2 (41.2–46.2)	1.7	41.6–46.5
Snout-vent length	43.7	45.8 (43.4–47.6)	1.5	43.5–49.1
Preanal length	58.8	61.5 (58.9–64.1)	1.6	58.3–63.4
Precaudal length	77.6	77.0 (75.0–78.4)	1.2	-
Interdorsal space	26.2	24.8 (23.6–26.8)	1.3	21.4–25.3
Dorsal-caudal space	10.9	11.1 (9.7–12.2)	0.7	-
Pectoral-pelvic space	19.0	21.0 (18.1–24.1)	1.8	13.7–20.0
Pelvic-anal space	13.0	12.2 (10.4–14.8)	1.2	11.0–13.2
Anal-caudal space	12.0	10.5 (10.1–11.1)	0.4	7.2–10.5
Pelvic-caudal space	28.8	26.9 (23.9–28.1)	1.3	-
Prenarial length	5.5	5.4 (4.4–6.0)	0.5	-
Preoral length	7.2	7.9 (7.4–8.3)	0.3	5.7–7.6
Eye length	3.8	4.6 (3.6–5.1)	0.4	3.3–5.1

......Continued on the next page