(Figs. 11–12)
Hyperoche mediterranea Senna, 1908: 159 –168, text figs. 1–10; pl. 1, figs. 1–2 (in colour).— Stephensen 1925: 229 (table). Barnard 1930: 415 (key). Chevreux 1935: 191. Hurley 1955: 147 –150, figs. 115–132. Hurley 1969: 33. Dick 1970: 57 –58, fig. 6. Shih et al. 1971: 165. Sanger 1973: 5, 7, 8 & 11 (tables), 10. Hirota 1974: passim. Flores & Brusca 1975: 10 –14, fig. 2. Laval 1980: 18 (table), 27, 37, fig. 2. Brusca 1981: 10 (list), 41, fig. 7g & 7 j. Vinogradov et al. 1982: 282 (key), 284–285, fig. 143. Hoogenboom & Hennen 1985: 234 –242, fig. 1. Zeidler 1992: 100, fig. 12. Lin et al. 1995: 122 (table). Shih & Chen 1995: 84 (key), 87–88, fig. 52. Lin et al. 1996: 229 (table). Zeidler 1998: 54. Barkhatov et al. 1999: 808 (table). Lavaniegos & Ohman 1999: 495 (table). Lima & Valentin 2001: 473 & 476 (tables). Escobar-Briones et al. 2002: 367 (list). Gates et al. 2003: 311. Zelickman 2005: xvi (list). Garcia-Madrigal 2007: 147, 191 (list). Gasca 2009 a: 88 (table). Lavaniegos & Hereu 2009: 151 (appendix). Mori et al. 2010: 9 (list).
? non [mis-identification; all juveniles, most likely of H. martinezii]— Steuer 1911: 674–677 (incl. key); pl. 1, figs. 1–5. Stephensen 1924: 79, fig. 33. Pirlot 1939: 37; pl. 2, figs. 5–6. Harbison et al. 1977: 467, 482 (table). Harbison et al. 1978: 239, 251 (table).
? Hyperoche medusarum [mis-identification]— Siegfried 1963: 8. Sorarrain et al. 2001: 407 –409.
Type material. Type material of Hyperoche mediterranea (females about 5 mm, males about 7 mm) could not be found in any major European institution and is considered lost. The type locality is the Mediterranean Sea, Gulf of Naples, near Messina, Prof. Mingazzini, October 1903 and February-April 1904.
Diagnosis. Females: Sexually mature at about 4 mm. Antennae 1 relatively short, about 0.7 x as long as head, slightly longer than A 2. Head length equal to first two pereonites combined. Pereon globular, length about 1.8 x pleon. Gnathopoda and pereopoda with very hirsute articles except for coxae and basis. Gnathopod 1; basis slightly shorter than remaining articles combined; merus spoon-shaped, projecting under carpus, almost to base of propodus, with fringe of setae on distal margin; carpal process with sharp, dactyl-like tip, extending slightly past distal margin of propodus, anterior margin denticulate; posterior and distal margin of propodus also denticulate; dactylus slightly curved, length almost half of propodus. Gnathopod 2 slightly longer and more slender than G 1 but similar in structure except that the merus is not produced as far under the carpus. Pereopod 3 slightly longer than P 4; basis length almost 3 x merus; carpus with postero-distal corner slightly produced, with denticulate posterior margin, slightly longer than merus and 0.7 x propodus; posterior margin of propodus denticulate; dactylus length about 0.4 x propodus. Pereopod 4 slightly longer than P 5–7; similar in structure to P 3 except the basis is relatively shorter and the propodus is relatively longer. Pereopods 5–7 are similar in size and structure. Pereopod 5; basis length about twice merus; carpus length about 1.2 x merus, about 0.6 x propodus; dactylus length 0.6–0.7 x propodus. Pereopods 6 & 7; like P 5 but basis relatively longer, especially P 7, and P 7 with coxa fused with pereonite. Epimeral plates with postero-distal corner rounded. Uropod 1; peduncle reaching almost to limit of peduncle of U 2 and to about 0.4 x peduncle of U 3; inner ramus slightly longer than outer, slightly longer than peduncle. Uropod 2; inner ramus slightly longer than peduncle, slightly longer than outer ramus. Uropod 3; inner ramus slightly shorter and marginally wider than outer, length about 0.7 x peduncle. Telson triangular, as long as wide, slightly shorter than half of peduncle of U 3.
Males: Sexually mature at about 5–6 mm. Antennae almost as long as entire animal. Pereon slender, slightly longer than pleon. Appendages similar to females in structure and relative lengths of articles, except for the following minor variations. Gnathopoda with merus not projected as far under the carpus. Pereopods 5–7 with marginally thicker articles. Epimeral plates relatively much longer and deeper. Urosome relatively less slender. Uropod 1; peduncle reaching limit of peduncle of U 2, to just past half peduncle of U 3; rami of similar length, inner margins with characteristic proximal excavation, length about 0.7 x peduncle. Uropod 2; inner ramus slightly longer than outer, slightly shorter than peduncle. Uropod 3; rami relatively broader and shorter, length about 0.6 x peduncle.
Material examined. S.W. Atlantic: Two juvenile males (SAMA C 7940), off southern Brazil [34 °04.10’S 47 ° 54 ’W], R/V Almirante Saldanha stn. 4600, surface, 3 October 1977. S.E. Atlantic: Two females (2 lots SAM), off Cape Town [33 °06’S 17 ° 53 ’E], Univ. Cape Town Ecol. Survey stns. WCD 45 U & 52 S, 60 m, 3 & 5 May 1960. N.E. Pacific: Two lots (SAMA C 7941 – 2), off Vancouver Island; 4 females, 3 males [49 ° 35.6 ’N 124 ° 26.53 ’W], Cruise IOS 0 0 29 stn. SET 1, 125–0 m, 16 August 2000; female [48.16 ’N 126 ° 39 ’W], Cruise IOS 0 331, BIONESS stn. A4, 50– 10 m, 24 September 2003. Female (ZMUC), off California [32 ° 57 ’N 128 ° 48 ’W], Jutlandia stn. 4773, 220 mw, 2 March 1933. Three lots (ZMUC), Gulf of Panama; male [06° 49 ’N 80 ° 25 ’W], Dana stn. 1205 IV, 300 mw, 14 January 1922; male & female [06° 48 ’N 80 ° 33 ’W], Dana stns. 1208 III & V, 300 & 3000 mw, 16 January 1922. S.E. Pacific: Two females, 4 males (4 lots—ZMUC), west of the Galapagos Islands [00° 18 ’S 99 °07’W], Dana stns. 3558 III, VII, VIII & IX, 2000, 300, 100 & 50 mw respectively, 18 September 1928. Female (USNM 1090278), Drake Passage, south of Chile [58 ° 51 ’S 70 ° 28 ’W], R/V Eltanin (USARP) Cruise 5, stn. 300, 1416 m (? bottom), University of Southern California, 3 November 1962. S.W. Pacific: Seven females, 9 males, 2 juveniles (9 lots—SAMA C 4577–4584 & 4586), Tasman Sea, ranging from east of Nelson Bay, New South Wales [32 ° 47 ’S 152 ° 40 ’E] to Bass Strait [39 ° 56 ’S 148 ° 36 ’E], mainly near surface, CSIRO R/V Warreen, 1939 – 40 (Zeidler 1998). Eight males (ZMUC), Bass Strait [38 °05’S 149 ° 45 ’E], surface, T. Mortensen, 11 September 1914. Female, male (SAMA C 7943 & 7944), off south-eastern Tasmania [44 ° 12 ’S 147 ° 24.5–28.9 ’E], CSIRO cruise 492, stns. 75 & 81, 14 & 15 November 1992. North, and east of New Zealand (12 lots—ZMUC); 3 males [34 ° 24 ’S 178 ° 42.5 ’E], Dana stn. 3630 II, 2000 mw, 17 December 1928; female [36 ° 23.5 ’S 175 ° 20 ’E], Dana, stn. 3636 II, 10 mw, 3 January 1929; female [37 °00’S 178 ° 16 ’E], Dana stn. 3638 II, 600 mw, 4 January 1929; 2 females, male & female, male [43 ° 40 ’S 176 ° 36 ’E], Dana stns. 3641 I & II, 300 & 100 mw, 8 January 1929; 6 females, 2 males (4 lots) [42 ° 32 ’S 174 ° 50 ’E], Dana stns. 3645 I–III & V, 1000, 600, 300 & 50 mw respectively, 12 January 1929; 4 females, 3 males (3 lots) [35 ° 36 ’S 171 ° 52 ’E], Dana stns. 3651 II–IV, 2000, 1500 & 1000 mw respectively, 22 January 1929. Southern Australia: Seven females, 9 males, 5 juveniles (SAMA C 7945), Robe jetty, eastern South Australia [37 °09’S 139 ° 45 ”E], WZ & L. Gershwin, 21 January 2002. Two females (SAMA C 7946), near Pearson Island, Nuyts Archipelago, South Australia [32 ° 12 ’S 133 ° 20 ’E], near surface, WZ, 24 May 2006.
Remarks. This is one of the smaller species of Hyperoche, like H. martinezii, reaching sexual maturity at about 4–6 mm. The most distinctive characters of this species are the form of the gnathopoda and the rounded pleonites. The only other species with similar pleonites, except for H. macrocephalus sp. nov., are H. martinezii and H. picta, but in those species the postero-distal corner of the merus is only slightly produced in gnathopod 1 and not at all for gnathopod 2, and in addition in H. picta the dactyls of the gnathopoda are inserted sub-terminally, in a small pocket on the medial face of the propodus. Another diagnostic character of this species is the setose articles of the gnathopoda and pereopoda, seemingly becoming more setose distally, especially for eastern Australian specimens, but this not always readily evident with some specimens being less hirsute. It is most similar to H. macrocephalus sp. nov. but is readily distinguished by the relatively smaller head and the structure of the gnathopoda and other minor characters, as detailed under that species.
This species has been recorded as an associate of the following ctenophores; Beroe forskalii (Lavaniegos & Ohman 1999), Pleurobrachia bachei (Flores & Brusca 1975), Luecothea multicornis & Ocyropsis maculata (Lavaneigos & Ohman 1999) and Lampetia pancerina (Laval 1980, Hoogenboom & Hennen 1985), and also the hydromedusae Eutonina indicans & Phialidium sp. (Brusca 1981). Lavaniegos and Ohman (1999) list additional hosts; Geryonia sp. (= Carmarina), Abyla sp. and Salpa sp.
Distribution. A relatively rare species known from widely separated records in tropical and temperate regions, mainly from surface waters. It seems to be widespread, although uncommon, in the Mediterranean Sea. In the north-eastern Pacific it ranges from British Columbia to the Gulf of California and in the west it occurs in the China Sea region. It seems to be more common in the south-western Pacific with several records from the Tasman Sea and north of New Zealand as well as from off Southern Australia. It has not been recorded from the North Atlantic, except for the discounted records of Pirlot (1939) and Harbison et al. (1977), which is surprising considering the many historical expeditions conducted in the region, and that it is linked to the Mediterranean Sea. Also, there are no records from the Indian Ocean.