Micronephthys sphaerocirrata ( Wesenberg-Lund, 1949 )

Ravara, Ascensão, Cunha, Marina R. & Pleijel, Fredrik, 2010, Nephtyidae (Annelida, Polychaeta) from southern Europe 2682, Zootaxa 2682 (1), pp. 1-68 : 25-27

Micronephthys sphaerocirrata ( Wesenberg-Lund, 1949)

Figures 7 , 8

Nephthys sphaerocirrata Wesenberg-Lund, 1949: 294 , figs. 24–26; Day 1953: 431.

Nephthys (Micronephthys) sphaerocirrata Day 1967: 347 , fig. 15.3A–D; not Gibbs 1971: 155.

Micronephthys sphaerocirrata Rainer and Hutchings 1977: 320 , figs. 12 and 41; not Fauchald 1968: 17, figs. 36–40.

Micronephthys sphaerocirrata? Imajima 1970: 116 , 121; Rullier 1972: 96; Campoy 1982: 506;? Nateewathana and Hylleberg 1986: 209; Laborda 2004: 415.

Type locality. Off Kharg, Persian Gulf.

Material examined. Indian Ocean. Persian Gulf, off Kharg: 13 m, Mar 1937, 2 complete and 1 incomplete spms, syntypes (ZMUC-Pol-1473 to 1475). South Africa, Gqutywa Estuary, eastern Cape

Province: 33º21.8’S, 27º21.5’E, 1 m, Jun 1998, 2 complete and 1 incomplete spms ( NMWZ 1999.071.002); South African Collection from Prof. J. H. Day, 9 complete and 26 incomplete spms ( NHM 1961.9.80/119) .

Description. Examined specimens up to 19 mm long for up to 73 chaetigers. See Fig. 7 for length and width measurements. Body small, slightly wider anteriorly, gradually tapering from median region to pygidium. Colour in ethanol light salmon; chaetae and aciculae amber. One pair of eyes present subdermally at level of chaetiger 2–3. Distal pharynx region with 10 (?) pairs of terminal, bifid papillae, separated by dorsal simple papilla ( Fig. 8A ); middorsal and midventral papillae absent; subdistal region with 22 rows of 7– 10 conical subterminal papillae, followed by several minute papillae, extending to base of pharynx; proximal region smooth. Prostomium subpentagonal, anterior margin straight or slightly convex, posterior margin Vshaped and extending over first chaetiger; antennae and palps conical to cirriform; palps slightly shorter than antennae, inserted ventrolaterally and medially on prostomium ( Fig. 8B ). Nuchal organs rounded. Parapodia biramous; interramal space “U-shaped”. Parapodia of chaetiger 1 anteriorly directed, parallel to prostomium; notopodial acicular lobes conical; pre- and postchaetal lamellae rudimentary; neuropodial pre- and postchaetal lamellae forming a cylinder around acutely pointed acicular lobes; dorsal cirri minute; ventral cirri cirriform. Acicular lobes of following parapodia conical; prechaetal lamellae rudimentary; postchaetal lamellae well developed but not extending beyond acicular lobes, rounded, becoming rudimentary posteriorly; dorsal cirri with sphaerical base and conical tip; ventral cirri subsphaerical becoming more elongated in posterior chaetigers ( Fig. 8C–E ). Branchiae absent. Chaetae of four kinds: barred chaetae in preacicular position, finely spinulated chaetae ( Fig. 8F ) and lyriform chaetae with unequal rami ( Fig. 8G ) in postacicular position, capillary chaetae in the neuropodia of first chaetiger. One acicula per ramus, posterior ones with curved tips ( Fig. 8H ).

Remarks. This species was first described by Wesenberg-Lund (1949) from the Persian Gulf with a number of subsequent records from other regions, including Thailand, South Africa, Mediterranean Sea and several localities in the Pacific Ocean ( Japan, Vietnam, NE Australia, Marshall and Solomon Islands and New Caledonia) (e.g. Day 1967; Fauchald 1968; Rainer & Hutchings 1977; Nateewathana & Hylleberg 1986; Laborda 2004). In this study we have not been able to verify the identity of the South African and Australian records. But the South African specimens were examined and the identification confirmed. As for the NE Australia, Rainer and Hutchings (1977) could not detect any differences between their specimens and the original description or the specimens they examined from South Africa. On the other hand, we examined specimens identified as M. sphaerocirrata from the Marshall (USNM 118681) and Solomon (NHM 1970.396) Islands that conform with M. stammeri and M. oculifera , respectively. The specimens recorded from Vietnam ( Fauchald, 1968) were already by Lee and Jae (1983) referred to the subspecies M. sphaerocirrata orientalis , described from Korea. This subspecies differs from M. s. sphaerocirrata by the number of pharynx papillae in each row (12–15 instead of 6–9/8–11) and the prominent preacicular lamellae. Imajima and Takeda (1985) also attributed specimens found in Japan to this subspecies. Nateewathana and Hylleberg (1986) identified specimens from Thailand as M. sphaerocirrata despite some minor differences in the parapodial lamellae proportions. The Thailand specimens differ in having the neuropodial prechaetal lamellae well developed (as long as the acicular lobes) and the notopodial postchaetal lamellae larger than the acicular lobes. We consider that the identification of these specimens as M. sphaerocirrata needs further study and comparison with type material. Specimens from the Mediterranean Sea were not available to us but Laborda (2004) reports a small difference in the number of pharynx papillae in each row (8–16). Until further confirmation we advise treat this record with caution.

Distribution. Atlantic Ocean (SW Africa); Indian Ocean (Persian Gulf, South Africa); Pacific Ocean (NE Australia) ( Rainer & Hutchings 1977). There are further reports of this species from southern Spain, Thailand and New Caledonia ( Nateewathana & Hylleberg 1986; Laborda 2004), but these records require confirmation.

Habitat. Fine and muddy sand, from shallow subtidal to 500 m depth ( Rainer & Hutchings 1977; Laborda 2004).

Figures

FIGURE 7. Relationships between: A. Number of segments and body length. B. Body length and body width. × M. minuta. M. sphaerocirrata. M. stammeri. M. minuta plot is based on the literature (Théel, 1879; Pettibone, 1963; Jirkov & Paraketsova, 1996). M. sphaerocirrata plot includes measurements from Wesenberg-Lund (1949) and Rainer & Hutchings (1977). M. stammeri plot includes measurements from Banse (1959), San Martín (1982) (original description of M. maryae) and Rainer & Kaly (1988) (for M. maryae).

FIGURE 8. Micronephthys sphaerocirrata. A. Pharynx, dorsal view. B. Prostomium and anterior chaetigers, dorsal view. C. Dorsal (left) and ventral (right) cirrus from anterior parapodia. D. Dorsal (left) and ventral (right) cirrus from median parapodia. E. Dorsal (left) and ventral (right) cirrus from posterior parapodia. F. Postacicular chaeta. G. Lyriform chaeta. H. Acicula from posterior chaetiger.