Lycaea intermedia, Zeidler, 2021

Zeidler, Wolfgang, 2021, Review of the hyperiidean amphipod family Lycaeidae Claus, 1879 (Crustacea: Amphipoda: Hyperiidea), Zootaxa 5081 (1), pp. 1-59 : 14-18

Lycaea intermedia sp. nov.

( Figs 4–5 )

Material examined. Holotype. Female, 5.7 mm (ovig.), NHMD-228206 , Dana stn. 3931 iii, S.W. Indian Ocean, N. of Madagascar [12°09’S 49°34’E], 300 mw, 19 December 1929.

Allotype. Male, 6.3 mm, NHMD-228225 , Dana stn. 3964 v, S.W. Indian Ocean, S.W. of Madagascar [25°19’S 36°13’E], 50 mw, 15 January 1930.

Paratypes. All from the following Dana stations. Central South Pacific : 1 male, NHMD-619243 , 3561 x [04°20’S 116°46’W], 50 mw, 24 September 1928 ; 1 female, NHMD-228151 , 3579 iv [20°56’S 160°03’W], 100 mw, 23 October 1928 ; 2 females, NHMD-228154 , 3584 iii [10°51.5’S 168°40’W], 400 mw, 29 October 1928 ; 1 male, NHMD-228159 , 3585 xi [11°S 172°37’W], 300 mw, 2 November 1928 ; 1 female, NHMD-228162 , 3587 xiii [11°S 172°37’W], 50 mw, 2 November 1928 ; 1 female, NHMD-228172 , 3748 ii [03°48’S 133°35’E], 150 mw, 10 July 1929 . Indian Ocean: E. of Sumatra to South Africa : 1 female, NHMD-228173 , 3815 vii [03°36’S 97°37’E], 500 mw, 10 September 1929 ; 2 females, NHMD-228180 , 3851 iii [05°27’S 93°50’E], 200 mw, 15 October 1929 ; 1 female, NHMD-228182 , 3851 iv [05°27’S 93°50’E], 100 mw, 15 October 1929 ; 1 female, NHMD-228185 , 3916 v [01°45’N 73°03’E], 50 mw, 4 December 1929 ; 1 female, NHMD-228187 , 3918 ii [00°35’N 66°09’E], 600 mw, 7 December 1929 ; 1 female, NHMD-228190 , 3919 iii [00°07’S 63°56’E], 300 mw, 8 December 1929 ; 1 male, NHMD-228196 , 3921 viii [03°36’S 58°19’E], 100 mw, 11 December 1929 ; 1 female, NHMD-228200 , 3926 i [08°27’S 50°54’E], 600 mw, 16 December 1929 ; 1 female, NHMD-228205 , 3930 v [11°55’S 49°55’E], 100 mw, 19 December 1929 ; 3 females, 1 male, NHMD-619435 , 3931 iii [12°09’S 49°34’E], 300 mw, 19 December 1929 ; 1 male, NHMD-228208 , 3931 iv [12°09’S 49°34’E], 200 mw, 19 December 1929 ; 3 females, 1 male, NHMD-228209 , 3932 ii [11°35’S 48°45’E], 300 mw, 20 December 1929 ; 1 female, NHMD-228212 , 3934 iv [11°24’S 52°05’E], 200 mw, 20 December 1929 ; 1 female, NHMD-228213 , 3934 v [11°24’S 50°05’E], 200 mw, 20 December 1929 ; 1 female, NHMD-228214 , 3935 ii [10°50’S 48°30’E], 400 mw, 21 December 1929 ; 1 male, NHMD-228217 , 3938 ii [09°10’S 45°17’E], 400 mw, 23 December 1929 ; 1 female, NHMD-228220 , 3951 iv [14°16’S 41°48’E], 50 mw, 7 January 1930 ; 1 male, NHMD-228224 , 3964 iii [25°19’S 36°13’E], 300 mw, 15 January 1930 . S.E. Atlantic: 3 females, 2 males, NHMD-228227 , 3980 x [23°26’S 03°56’E], 50 mw, 17 February 1930 . Tasman Sea: 1 male, NHMD-228171 , 3665 iv [29°37’S 156°46’E], 100 mw, 25 February 1929 .

Other material. Indian Ocean: All but last lot from the following Dana stations, mostly in poor condition. 1 female, NHMD-228184 , 3907 iii; 1 male, NHMD-228186 , 3917 vii; 1 female, 1 male, NHMD-228188 , 3918 iv; NHMD-228192 , 3919 v; 4 females, NHMD-228197 , 3924 iv; 1 male, NHMD-228199 , 3924 v; 1 female, NHMD- 228201 , 3926 iii; 1 male, NHMD-228202 , 3927 iii; 1 female, NHMD-228204 , 3929 vii; 2 females, NHMD- 228210–11 , 3932 iii, 3932 x; 2 females, NHMD-228215 , 3936 v; 2 females, NHMD-228218 , 3948 ii; 1 female, NHMD-228219 , 3949 iii; 1 male, NHMD-228221 , 3958 ii. N.E. Atlantic: 1 female, NHMD-228139 , 1145 ix, 1 male, NHMD-228140 , 1145 x. South China Sea : 1 male, NHMD-228238 , 4815 . S. of Japan: 2 females, NHMD- 228237 , Jutlandia stn. 4775 .

Description of holotype. Female, 5.7 mm (ovig.). Head relatively large, much deeper than long (about 1.6 x), almost as long as first 5 pereonites combined. Buccal mass protruded well below head. Pereonite 2 with slight dorsal hump. G1 and G2 sub-chelate, morphologically similar, G2 slightly longer than G1; basis of G1 slightly broader and shorter than G2; carpus rectangular with sharp postero-distal tooth, reaching just past base of dactylus; propodus with postero-distal corner produced posteriorly to dactylus; carpus and propodus without small serrations on distal and posterior margins; dactylus slender, length about 0.6 x propodus. P3–6 with relatively short, stubby dactylus, those of P3 and P4 about 0.2 x length of propodus. P3 and P4 morphologically similar, P4 slightly longer than P3; merus marginally inflated anteriorly, slightly shorter than propodus, about 0.5 x basis; carpus length about 0.7 (P3) or 0.8 (P4) x propodus. P5 length about 1.2 x P4 and about 1.4 x P6; basis oval-shaped, length about 2 x maximum width; merus sub-equal in length to propodus, about 0.6–0.7 x basis; carpus length about 0.7 x propodus. P6 basis oval-shaped, length about 1.5 x maximum width, slightly shorter than basis of P5; merus with slightly inflated anterior margin, sub-equal in length to propodus, about 0.5 x basis; carpus length about 0.6 x propodus; anterior margin of carpus and propodus, and antero-distal corner of merus, slightly serrated. P7 basis with slightly bulging posterior margin, length about 1.8 x maximum width, about 0.9 x basis of P6; length of remaining articles together about 0.6 x basis; propodus with antero-distal corner produced into small, rounded lobe; dactylus sharp, hook-like. U1 peduncle relatively long, slightly more than 3.3 x length of exopod; rami relatively slender, equal in length. U2 endopod fused with peduncle. Telson slightly longer than width at base, with rounded tip.

Description of allotype. Male 6.3 mm. Like holotype female except for the following. Head more rounded, marginally deeper than long, almost as long as first 5 pereonites combined. Buccal mass barely protruded below head. A1 callynophore without antero-distal corner; postero-distal corner small, rounded, separated from following article by distinct notch. Pereonite 2 without dorsal hump. Dactylus of G1 and G2 slightly longer, almost 0.7 x propodus. P5 length about 1.4 x P4 and about 1.3 x P6; basis rectangular; merus length about 0.8 x propodus. P6 merus slightly shorter than propodus; dactylus retractile in small hollow at base of propodus. P7 basis broader, length about 1.5 x maximum width; length of remaining articles together slightly more than 0.4 x basis.

Variations. Ovigerous females of Lycaea intermedia ranged in size from 5.0 mm (NHMD-228180) to 6.1 mm (NHMD-228185). Males seem to be mature at about 6.0 mm but the largest male recorded was 9.2 mm (NHMD- 228227), but this was probably an exceptional example because the next largest specimen was only 7.3 mm (NHMD- 228159). Whether or not the dactylus of P6 is retractile is difficult to determine unless it is at least partly retracted. In some specimens it is only partly retracted and sometimes only on one side. However, this character was recorded in several males apart from the allotype (NHMD-228171; 228196, 228224, 228227) as well as in several females (NHMD-228173, 228182, 228185, 228227).

Etymology. Lycaea intermedia shares some characters with both L. bovallii and L. nasuta but is distinguished from them by a combination of several characters as detailed below. Hence it is considered to be somewhat “intermediate” between the two.

Remarks. Lycaea intermedia was extracted from a lot labelled “ L. nasuta ” amongst the collections of Dana material in the NHMD. It was probably identified as such based on the morphology of U 2 in that the inner ramus is fused with the peduncle. This would now also include L. bovallii . However, only three lots were identified as L. nasuta , the remainder were determined as L. bovallii or L. intermedia . Vinogradov et al. (1982, 1996) erroneously describe and illustrate G1 and G2 of L. nasuta as being similar to L. pulex and it is likely that this reference was used to determine the Dana material resulting in the mis-identification.

Lycaea intermedia is most similar to L. bovallii in the general habitus of both sexes, the relatively long peduncle of U1 and in that the inner ramus of U2 is fused with the peduncle, but is readily distinguished from it by the shorter, stubby dactylus of P3–6 and by the absence of serrations on the postero-distal corners of the carpus and propodus of G1 and G2. In addition, females of L. intermedia are distinguished by the small dorsal hump on the second pereonite, a character which is also shared with L. nasuta (also found in some specimens of L. lilia ), and in males the callynophore of A1 is without an antero-distal hump, a distinctive character of L. bovallii and L. vincentii . In addition to the above, it also resembles L. nasuta in that P3–6 have a relatively short dactylus but differs in that the dactylus of G1 and G2 is relatively longer and the morphology of both is similar, whereas for L. nasuta the propodus of G2 extends well beyond the postero-distal corner of the carpus, unlike G1. In addition, the head of males is rounded, without the characteristic anterior knob found in L. nasuta . Another distinctive character of L. intermedia is the retractile dactylus of P6, a character not found in any other species except L. osbornae sp. nov. (infra) but it is not evident in all specimens and can be difficult to determine unless the dactylus is at least partly retracted.

A salp associate has not been recorded for this species.

Distribution. The Dana collections, as detailed above, indicate that this species is widely distributed in the tropical regions of the Pacific and Indian Oceans, with a few records from the Atlantic Ocean and the Tasman Sea. It seems to be most common in the Indian Ocean.

Figures

FIGURE 4. Lycaea intermedia sp. nov. Holotype female, 5.7 mm (ovig.), NHMD-228206. Scale bars = 0.5 mm (habitus, G1–P7); 0.2 mm (A1, Us); 0.1 mm (A1).

FIGURE 5. Lycaea intermedia sp. nov. Allotype male, 6.3 mm, NHMD-228225. P6′ from female 5.3 mm, collected with holotype. P6″ from female 6.1 mm (ovig.), NHMD-228185. Scale bars = 0.5 mm (habitus, A2, G1–P7); 0.2 mm (A1, Us).