Lanceola sphaerica Vinogradov, 1970

Zeidler, Wolfgang, 2021, Redescription of two rare, deep-sea species of hyperiidean amphipod, Lanceola loveni antarctica Vinogradov, 1962 and L. sphaerica Vinogradov, 1970 (Crustacea: Amphipoda: Hyperiidea: Lanceolidae), Zootaxa 5067 (1), pp. 106-114 : 111-113

Lanceola sphaerica Vinogradov, 1970

Lanceola clausi var. sphaerica Vinogradov 1957: 196 , fig. 6.

Lanceola sphaerica Vinogradov, 1970: 383 , 386–388, figs 1–2.— Vinogradov et al. 1982 / 1996: 73–75 /84–86, fig. 20.—Zeidler 2009: 44–45, fig. 13.— Zeidler 2019: 514 .

Material examined. Southern Ocean: immature female ( USNM 1090248 ), Amundsen Sea, Cruise 11, station 930 [70°08’S 109°48’W], 1,391 m, 19 January 1964 (figured here) . SE Pacific: immature female ( USNM 1089971 ), off Chilean coast near Valdivia, Cruise 6, station 326 [38°19’S 74°34’W], 1,691–2,072 m, 25 November 1962 .

Type material. Lanceola sphaerica was first described as a variety of L. clausi from two damaged specimens, a mature female (8 mm) and a male (9 mm), both caught in the Kurile-Kamchatka region of the North-West Pacific. The female from Vityaz station 2076 [43°39’N 149°24’E], 4,200 –7,800 m, 9 May 1953 and the male from Vityaz station 2208 [49°23’N 158°45’E], 0–6,500 m, 22 June 1953 ( Vinogradov 1957). Later, Vinogradov (1970) established it as a full species with the availability of a well-preserved male (5.5 mm) from the same general area; Vityaz station 5626 [45°11’N 152°28’E], 3,000 –4,000 m, 23–24 August 1966. All three specimens are in the Zoological Museum of the Moscow State University (Mb–1051, 1052, 1053).

Description of immature female 4.5 mm ( Fig. 3 ). Pereonites 1–4 inflated, almost spherical. Head without rostrum. Eyes very small, reniform, without crystalline cones. A1 slightly longer than head and first pereonite combined. A2 as long as A1 with two long setae terminally. G1; basis relatively slender, slightly shorter than remaining articles combined; carpus length 0.5 x basis, distal margin width about 1.3 x proximal margin of propodus; propodus conical-shaped, length about 2 x proximal width; dactylus length almost 0.5 x propodus. G2 much longer and slenderer than G1; basis length about 0.7 x remaining articles combined, about 2 x carpus length; propodus gradually tapering to narrow distal margin, length about 1.4 x carpus; dactylus inserted terminally to propodus, length about 0.4 x propodus. P3 and P4 similar in length and morphology; basis length slightly more than 2 x merus; merus with distinct antero-distal bulge, maximum width about 0.8 x length; carpus length 1.6 x merus for P3, 1.8 x merus for P4; propodus length 1.3 x carpus for P3, 1.1 x carpus for P4; dactylus length slightly more than 0.3 x propodus. P5–7 all with relatively long, slender articles and fully retractile, hooded dactyls but propodus not club-like distally. P5 slightly shorter than P4; basis length almost 2 x merus; carpus length 1.3 x merus, 0.8 x propodus; dactylus in relatively broad hollow. P6 length almost 1.3 x P5, slightly longer than first four pereonites combined; basis length about 2 x merus; merus with very slight postero-distal bulge; carpus length 1.5 x merus; propodus length about 1.4 x merus; dactylus strongly curved, pressed against anterior margin of propodus. P7 length 0.7 x P6; basis length 2.5 x merus; merus with slight postero-distal bulge; carpus length 1.2 x merus, about 0.6 x propodus. Urosome with relatively slender peduncles and rami. Rami of all uropoda more or less sub-equal in length, with slightly serrated margins. Peduncles and rami of U1 & U2 similar in length. Peduncle length of U3 slightly less than rami. Telson acute, apex rounded; length about 1.5 x width at base, reaching to about the middle of peduncle of U3.

Remarks. Lanceola sphaerica is distinguished from all its congeners by a combination of several characters; i) the inflated pereon (especially in females); ii) the relatively long dactyls of P3–7 (especially P 3–4 in mature males); iii) the structure of P5 becoming sub-chelate in males; and iv) the relatively short telson. It is clearly most similar to the highly variable species, L. clausi , in the general habitus and the relative lengths of the pereopods but is readily distinguished by the slightly more inflated pereon and the relatively longer dactyls of P3–7. The female specimen described here is similar to L. clausi pirloti Shoemaker, 1945 in that the antennae are of similar length and the merus of P3–4 has a distinct antero-distal bulge, but differs from it in that the basis of the gnathopoda is slender; P6 is relatively longer and the uropoda are slenderer. In the long dactyls of P3 and P4, it resembles L. longidactyla Vinogradov, 1964 but in that species the dactyls are relatively much longer and P5 is not modified. It also resembles L. chelifera Vinogradov, 1970 , especially in the modification of P5 but in that species the dactylus of P5 is not retractile or hooded and the structure of P3 and P4 is completely different.

As noted by Vinogradov (1970), females of L. sphaerica differ from males in the following characters: i) P3 and P4 are more weakly armed and the dactyls are relatively shorter; ii) the articles of P5 are more linear, with less armature and the propodus is not robust and the dactylus is not as strong, not becoming sub-chelate. The specimen described here agrees with these characters and there are only very minor differences in the relative lengths of articles that can be determined from the limited information provided for the female by Vinogradov (1957, 1970). The sexual dimorphism exhibited in the morphology of P5 seems to become more prominent in mature males. Like L. clausi , L. sphaerica seems to occur in the colder waters of both Hemispheres.

Distribution. Known only from the Kurile-Kamchatka region of the Pacific Ocean, the Amundsen Sea, Antarctica and the South-East Pacific, as detailed above. The latter is a new distribution record for L. sphaerica . Vinogradov (1970) records it as “one of the most deeply-living hyperiids, being restricted to the abyssopelagic zone (including the trench waters) and does not rise above 3,000 m into the bathypelagic”, based on the specimens from the Kurile-Kamchatka region. It is recorded here from 1,391 m and 1,691 –2,072 m.

Figures

FIGURE 3. Lanceola sphaerica Vinogradov. 1970: female 4.5 mm (USNM 1090248), Amundsen Sea, 1391 m. Scale bars: 0.5 mm (habitus); 0.2 mm (remainder).