Paraprionospio inaequibranchia (Caullery, 1914)

Yokoyama, Hisashi, 2007, A revision of the genus Paraprionospio Caullery (Polychaeta: Spionidae), Zoological Journal of the Linnean Society 151 (2), pp. 253-284 : 267-270

PARAPRIONOSPIO INAEQUIBRANCHIA

( CAULLERY, 1914) ( FIGS 10 , 11 )

Prionospio (Paraprionospio) pinnata inaequibranchia Caullery, 1914

Material examined: Four syntypes of Prionospio pinnata var. inaequibranchia: ZMA v.pol .1568, Station 2, Java Sea, 37 m deep; ZMA v.pol .1566, Station 51, Java Sea, 69–91 m; ZMA v.pol .1571, Station 181, Ambon, Banda Sea, 54 m; ZMA v.pol .1688, Station 261, Banda Sea, 27 m. One complete specimen reported as Paraprionospio lamellibranchia by Hartman (1975): 110 setigers measuring 29 mm long and 0.7 mm wide, Station RH33, mouth of Godavari estuary, Kakinada Bay, India. Two specimens (OMNH-Iv 4888): off Matang mangroves, Perak, Malaysia, 2.5 m deep, 17.x.1995, collected by A. Arshad.

Description: The following description is based on syntypes ( Fig. 10 ) and a specimen reported as Paraprionospio lamellibranchia by Hartman (1975) ( Fig. 11 ) and specimens collected from Malaysia. Prostomium fusiform with round or bluntly pointed anterior end. Peristomium without pigment patch and marginal papilla. Two pairs of dark-brown eyes in trapezoidal arrangement occasionally visible on prostomium. Three pairs of branchiae on setigers 1–3; first branchiae usually largest, third branchiae to setiger 9, lamellae reducing to low ridge. In anterior setigers, notopodial setae bilimbate capillaries only, arranged in three rows, replaced gradually by long slender non-limbate capillaries posteriorly. Notopodial hooded hooks beginning on setiger 30–35, numbering about three per parapodium; each hook with 4 pairs of apical teeth above main fang. Neuropodial setae in anterior setigers bilimbate capillaries only, replaced by 9–13 hooded hooks and alternating non-limbate, slender capillaries, and a punctate sabre seta from setiger 9. Neuropodial hooks with 4–5 pairs of apical teeth above main fang ( Fig. 11C ). Dorsum of setigers 13–17 with transverse series of slightly raised three ridges. Well-developed membranous dorsal crests appearing on setigers 21 and present on variable number of setigers (setiger 26–29), accompanied by semi-transparent dorsal cuticle ( Fig. 11B ). Interparapodial pouches appearing between setigers 9 and 14, present on posterior setigers ( Fig. 11A, B ). Pygidium with long median anal cirrus and two short, lateral cirri.

smallest ( Figs 10 , 11A ). All branchiae bearing lamellae; in proximal region of branchial shaft, lamellae consisting of two lanceolate and triangular plates; thereafter two plates connecting at their bases; in middle and distal regions, two plates united completely and showing flabellate-shape. Filament present at base of third branchia ( Figs 10 , 11A ). Notopodial postsetal lamellae elongate subtriangular on setigers 1–3, becoming low rounded back to about setiger 11 reducing in size; in succeeding setigers, lamellae elevated posteriorly, becoming triangular and lanceolate posteriorly ( Fig. 11A, B ). Anterior neuropodial postsetal lamellae elongate distally pointed, becoming low rounded posterior to setiger 3; posterior Variation among syntypes and other specimens: Syntypes, all anterior fragments with 18–33 setigers, measuring 9–14 mm long and 1.2–1.8 mm wide (setiger 5, excluding parapodia). Eyes not visible on prostomium. All branchiae bearing lamellae except in basal region and distal tip ( Fig. 10 ). Membranous dorsal crest connecting notopodial postsetal lamellae on setigers 21–23 ( v.pol .1568, setiger 24 and succeeding setigers missing). Semi-transparent, dorsal cuticle found in setigers 21–27 ( v.pol .1688). Interparapodial pouches beginning between setiger 10 ( v.pol .1566, 1571) and setiger 15 ( v.pol . 1568) and present on variable number of setigers (three in v.pol . 1571 to ten in v.pol . 1688).

A specimen reported as Paraprionospio lamellibranchia by Hartman (1975) complete with 110 setigers measuring 29 mm long and 0.7 mm wide ( Fig. 11 ). Prostomium with bluntly pointed anterior end ( Fig. 11D ). Two inconspicuous eyes on widest part of prostomium. First branchiae extremely large (distal end of right branchia regenerating) extending posteriorly to setiger 8, third branchia smallest extending to setiger 5 ( Fig. 11A ). All branchiae bearing lamellae consisting of single flabellate plate; first branchia bearing 43 lamellae (left side). Notopodial hooded hooks appear from setiger 35. Neuropodial hooks with four pairs of apical teeth above main fang ( Fig. 11C ). Two transverse ciliated bands on dorsum of setigers 6–16 ( Fig. 11A ). Membranous dorsal crest connecting notopodial postsetal lamellae ( Fig. 11B ) on setigers 21–29. Ventral upper margin of setigers 5–12 protruding anteriorly to form collar-like process incised midventrally, but not forming a true collar or flap with a free margin ( Fig. 11D ). Interparapodial pouches present on setigers 9–76, well developed except in anterior few setigers ( Fig. 11A, B ).

Specimens collected from Malaysia incomplete with 64–89 setigers, measuring 52–53 mm long and 1.6– 1.7 mm wide. Two pairs of dark-brown eyes in trapezoidal arrangement on prostomium. One specimen bearing yellowish-brown pigment patches on lateral sides of prostomium. First branchiae extending posteriorly to setiger 7, second branchiae equal in length to first branchia, but narrower, third pair shortest, extending to setiger 3. In proximal region of branchial shaft, branchial lamellae consisting of two (lanceolate and triangular) plates; thereafter two plates connecting at their bases; in middle and distal regions, two plates united completely and showing flabellate shape. Notopodial hooded hooks beginning on setiger 30 or setiger 33. Neuropodial hooded hook with four or five pairs of apical teeth. Well-developed membranous dorsal crests on setigers 21–26. Interparapodial pouches beginning on setiger 10 or setiger 14, present on posteriormost setiger of anterior fragments.

Remarks: Paraprionospio inaequibranchia was originally described as a new variety of Paraprionospio pinnata by Caullery (1914) as having three pairs of branchiae with different sizes based on specimens collected from the Java Sea and Banda Sea. Paraprionospio inaequibranchia differs from Paraprionospio pinnata by the presence of a thread-like filament at the base of the third branchia and membranous dorsal crests beginning from setiger 21. Such differences should be taken as being of specific significance.

Hartman (1975) described Paraprionospio lamellibranchia based on the holotype collected from the Mozambique Channel at a water depth of 423 m. She also reported the occurrence of Paraprionospio lamellibranchia from the northern Indian Ocean at stations in the Arabian Sea and Bay of Bengal at depths to 64 m, specimens of which also served for the original description of Paraprionospio lamellibranchia . Examination of the holotype of Paraprionospio lamellibranchia and a specimen collected from Station RH 33 in Kakinada Bay, Bay of Bengal, however, revealed that the two specimens differ morphologically. The latter specimen has flabellate lamellar plates of branchia, non-limbate slender capillaries in the 9th neuropodium and four pairs of apical teeth of hooded hooks, which were not found in the holotype of Paraprionospio lamellibranchia . On the other hand, no morphological distinction was found between the specimen from Kakinada Bay and the syntypes of Paraprionospio inaequibranchia . The specimen collected from Kakinada Bay agrees also with the specimens collected from the Strait of Malacca except for the number of setigers bearing a dorsal crest (i.e. setigers 21–29 vs. setigers 21–26). These findings suggests that the specimens collected from the three localities, i.e. Indonesia, Malaysia and India, are conspecific. The posteriormost setiger in the syntypes of Paraprionospio inaequibranchia where a dorsal crest occurs is inconspicuous due to worn specimens with anterior fragments only. At the present time, the posteriormost setiger in Paraprionospio inaequibranchia is shown as a range (i.e. from setiger 26 to setiger 29), which was determined from specimens collected from Kakinada Bay and Strait of Malacca.

Distribution: Indonesia; Malaysia; India.

Figures

Figure 10. Paraprionospio inaequibranchia, syntype (ZMA, v.pol. 1688). Anterior end, in dorso-lateral view. Notopodial lamella on setiger 9 and neuropodial lamellae on setigers 3–8 are broken.

Figure 11. Paraprionospio inaequibranchia, reported as Paraprionospio lamellibranchia by Hartman (1975). The specimen was collected from Station RH33 in Kakinada Bay, India. A, anterior end, in lateral view; B, setigers 24–26, in lateral view, showing interparapodial pouches, membranous dorsal crests and semi-transparent dorsal cuticles; C, neuropodial hooded hook from setiger 22; D, anterior end, in ventral view.