Glossobius impressus Say 1818

Glossobius impressus (Say, 1818)

Figures 1–3

Cymothoa impressa Say, 1818: 397.— De Kay, 1844: 48.

Ceratothoa linearis Dana, 1853: 752, pl. 50: figs l (a–d).— Gerstaecker, 1882: 260.— Stebbing, 1893: 354.— Richardson, 1900: 221; 1901: 529.

Ceratothoa exocoeti Cunningham, 1871: 499, pl. 59: fig. 5.— Gerstaecker, 1882: 260.

Glossobius linearis.— Schioedte & Meinert, 1883: 301, pl. 12: figs. 1–9.— Hansen, 1895: 18, pl. 2: figs. 2–2d.— Brian & Dartevelle, 1949: 176.

Ceratothoa impressa. — Richardson, 1905: 234 –236, figs. 236–240; 1913: 2, 6.— Fowler, 1912: 292 –293, pl. 83.— Tattersall, 1921: 214.— Stephensen, 1948: 43 –44, fig. 9.— Schultz, 1969: 155 –156, fig. 233.—Anonymous, 1971: 16–17.— Lincoln, 1971a: 103 –104, photograph facing p. 90; 1971b: 184.— Trilles, 1972: 7 –9, figs. 3–24, photographs 5, 6; 1973: 1253– 1255, pl. 2: figs. 14–16.— Bowman, 1978: 217.— Kussakin, 1979: 287, fig. 153.— Kurochkin, 1980: 289.

Meinertia impressa. — Nierstrasz, 1915: 89 –90; 1918: 119.

Codonophilus impressus. — Nierstrasz, 1931: 131.

Glossobius impressa. — Avdeev, 1981: 1160, 1164; 1982a: 70.

Glossobius impressus. — Avdeev, 1982b: 65 –67, fig. 2, no. 4; 1985: 89.— Bruce & Bowman, 1989: 22 –26, figs. 15–17.— Kensley & Schotte, 1989: 183 –185, fig. 83(B).— Williams & Williams, 2000: 155.— Luque, Vieira, Takemoto, Pavanelli & Eiras, 2013: 1449 –1470.

Not Ceratothoa impressa. — Berkeley & Houde, 1978: 636 [= Glossobius hemiramphi Williams & Williams, 1985].

Type and type locality. The holotype is held at the Academy of Natural Sciences Museum, Pennsylvania (ANSP 1608). Type locality is Cape May, New Jersey from an unknown host (Bruce & Bowman 1989).

Material examined. ♀ (ovig. 25 mm), 29°17.00'S, 153°49.00'E, east of Evans Head, New South Wales, Australia, 7 November 1978, coll. FRV “Kapala” (AM P53749); Note: specimen with missing antennule and antenna, broken rostrum and a missing dactylus on left pereopod 1 (ventral view) without host data. ♀ (ovig. 32 mm), 22°S, 4°W, off Namibia, from the mouth of flying fish, coll. Nelson (SAM C345).

Ovigerous female. Length 25 mm, width 6 mm (Australian specimen, AM P53749).

Body 3.7 times as long as greatest width, body dorsal surface smooth and polished in appearance, body widest at pereonite 1–4, narrowest at pereonite 7, body lateral margins subparallel. Cephalon 0.8 times longer than wide, visible from dorsal view. Frontal margin apex rounded, (broken). Eyes well-developed, 0.3 times width of head. Labrum lateral margin convex, anterior margin broad.

Pereonite 1 anterior margin produced and smooth, anterolateral angle with distinct produced bulbous lobe and laminar flange; pereonite 2 with distinct produced bulbous lobe and laminar flange similar to pereonite 1, posterolateral angles narrowly rounded; pereonite 7 posterior margin weakly arched. Coxae 2–3 posteroventral angles with weak produced points; 4–7 with weakly oblique carina. Pleonites 2–5 not overlapped by pereonite 7, pleonites 2–5 similar width to pereonite 7; pleonite 5 with posterolateral angles not overlapped by lateral margins of pleonite 4. Pleotelson 0.4 times as long as anterior width, lateral margins convex, posterior margin weakly emarginate.

Pereopod 1 basis 1.1 times as long as greatest width; ischium 1.3 times as long as basis; merus proximal margin with slight bulbous protrusion; carpus with rounded proximal margin; propodus 1.4 times as long as wide; dactylus slender, 1.2 times as long as propodus, 3.2 times as long as basal width. Pereopod 2 propodus 1.2 times as long as wide; dactylus 1.4 times as long as propodus. Pereopod 6 basis 0.6 times as long as greatest width, ischium 1.1 times as long as basis, propodus 1.4 times as long as wide, dactylus 2.5 times as long as propodus. Pereopod 7 basis 0.6 times as long as greatest width; ischium 1.2 times as long as basis, without protrusions; merus proximal margin with bulbous protrusion, merus 0.3 times as long as ischium, 0.4 times as long as wide; carpus 0.3 times as long as ischium, without bulbous protrusion, 0.6 times as long as wide; propodus 0.8 times as long as ischium, 1.4 times as long as wide; dactylus slender, 1.8 times as long as propodus, 3.7 times as long as basal width.

Pleopod 1 exopod 0.7 times as long as wide, lateral margin strongly convex, distally weakly rounded, mesial margin straight, peduncle 0.3 times as long as wide, without retinaculae.

Uropod not extending beyond pleotelson posterior margin, peduncle 1.0 times longer than rami length, peduncle lateral margin without setae; marginal setae absent. Endopod apically slightly pointed, 2.5 times as long as greatest width, lateral margin proximally convex, mesial margin weakly convex. Exopod similar length to endopod, 2.5 times as long as greatest width, apically rounded, lateral margin weakly convex, terminating with no setae, mesial margin weakly convex.

Colour. Cephalon to pereonites 1–3 and appendages appearing dark brown to black, gradually lightening towards posterior end of body, similar to that observed by Bruce & Bowman (1989).

Size. Ovigerous female: 24–40 mm, pre-ovigerous female: 28–39 mm, mature male: 8–11 mm (Bruce & Bowman 1989).

Remarks. Glossobius impressus can be identified by the prominent lateral lobes on pereonites 1 and 2; broad rostrum; median emargination of pleotelson posterior margin; slender, long and weakly twisted pereopod 3 dactylus, twice as long as pereopod 3 propodus; bulbous protrusion on pereopods 6 and 7 merus; and strongly convexed lateral margins of pleopods. Males have distinct eyes; lack the distinct lateral lobes on pereonites 1 and 2; subparallel bodies; pereonites 1–6 of similar length; smooth pleopod margins and similar pereopod morphology as seen in Trilles (1972) and Bruce & Bowman (1989).

The variations observed in the Australian specimen (in comparison to the holotype) are the slender subparallel body, 3.7 times longer than wide (3.5 times longer than wide in holotype); less prominent lateral lobes on pereonites 1 and 2; pereonite 7 posterior margin not overlapping pleon; pleotelson length and width size similar to pleonites 2–5 (pleotelson greatest length approximately 0.5 times as long as pleonites 2–5). The African specimen is more similar to the holotype, differing in the more slender antennae and the subequal uropodal rami. Kensley & Schotte (1989) described the Caribbean specimen as having small but distinct eyes, uropod reaching half way along the posterior margin of pleotelson and exopod shorter than endopod.

Glossobius anctus differs from G. impressus in that it does not have prominent lateral lobes on pereonites 1 and 2; larger labrum (2.0 times); longer than wide pleopods, with smoother endopod and exopod margins; broader coxae margins and a pleotelson with a subtruncate posterior margin.

Glossobius impressus has been reported from four genera of Exocoetidae: Cheilopogon Lowe, 1841, Cypselurus Swainson, 1838, Exocoetus Linnaeus, 1758 and Hirundichthys Breder, 1928. Glossobius impressus has previously only been known to occur in the tropical and subtropical oceans (Bruce & Bowman 1989; Williams & Williams 2000). Current material from New South Wales and southern Africa indicates that the species can occur in warm-temperate waters.

Distribution. Indian Ocean: Makassar Strait (Nierstrasz 1915); South Pacific Ocean: New South Wales, Australia (present material), New Caledonia (Trilles 1972); South Atlantic Ocean: southern Africa (present material), Brazil (Schioedte & Meinert, 1883; Kensley & Schotte 1989; Luque et al. 2013); North Atlantic Ocean: Cape May, New Jersey (Say 1818); Gulf Stream, Florida (Dana 1853, Schioedte & Meinert 1883); Cape Verde (Cunnigham 1871); Caribbean (Kensley & Schotte 1989; Williams & Williams 2000); Senegal (Kensley & Schotte 1989).

Hosts. Known from the family Exocoetidae; spotfin flying fish Cheilopogon furcatus (Mitchill, 1815) (see Avdeev 1982b), bandwing flying fish Cheilopogon exsiliens (Linnaeus, 1771), Cypselurus sp. (see Avdeev 1982b) Exocoetus sp. (see Avdeev 1982b; Luque et al. 2013), mirrorwing flying fish Hirundichthys speculiger (Valenciennes, 1847) (see Avdeev 1982b; Kensley & Schotte 1989; Bruce & Bowman 1989), fourwing flying fish Hirundichthys affinis (Günther, 1866) (see Bruce & Bowman 1989; Williams & Williams 2000).

Accidental host occurrence includes swordfish Xiphius gladius (Linnaeus, 1758) (see Trilles 1972) and yellowfin tuna Thunnus albacares (Bonnaterre, 1788) (see Bruce & Bowman 1989) Coryphaena sp. (Avdeev 1982b) and Sphyraena sp. (Avdeev 1982b) as exocoetid fishes are part of their diet (Bruce & Bowman 1989).