Naineris grubei ( Gravier, 1908 )

Blake, James A., 2017, Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America, Zootaxa 4218 (1), pp. 1-145 : 101-103

Naineris grubei ( Gravier, 1908)

Figures 48–50

Scoloplos grubei Gravier, 1908: 42 –43; 1909: 646–649, pl. 18, figs. 49–57. Naineris grubei: Hartman 1957: 303 ; Blake 1996: 20 –22, fig. 1.8.

Material examined. Northern Chile, Iqique, LUCE Sta. M-131, intertidal, red rocks in pools (1, SMNH 154447 ) .— Southern Chile, Seno Reloneavi, Canal Tenglo, between Isla Tengo and Angelmó, LUCE Sta. M-13, 0– 6 m (1, SEM, JAB); Seno Reloneavi , Isla Tenglo, the bay on the South Side , LUCE Sta. M-60, intertidal (4, SMNH 154440 ) ; Bahía de Ancud, between Punta San Antonio and Punta Colorado, LUCE Sta. M-55, intertidal (1, SMNH 154444 ); Golf Corcovado, Boca del Guafo , Isla Guafo, the anchorage E of Punta Weather, LUCE Sta. M-70A, 25 m (1, SMNH 154450 ) ; Golfo de Ancud, Canal Caicaen, E of the mouth of Canal Quigua, LUCE Sta. M- 45, 18 m (1, SEM, JAB).— Straits of Magellan , near the estuary of Río los Ciervos, S of Punta Arenas, LUCE Sta. M-115, intertidal (1, SMNH 154449 ) .

Description. All specimens incomplete; largest fragment nearly complete, 85 mm long and 2.4 mm wide for 146 setigers. Color in alcohol: dark brown.

Largest specimens with prostomium truncate, slightly rounded on frontal margin ( Figs. 48 A, 49A, 50A); eyespots lacking; smaller specimens with prostomium more pear-shaped, blunt on anterior margin ( Fig. 48 A); peristomium with two achaetous rings in juveniles and smaller specimens ( Fig. 49 A), reduced to a single achaetous ring in larger specimens ( Figs. 48 A, 50A); proboscis not observed. Thoracic region with 19–20 setigers (17 according to Gravier 1909), appearing dorsally compressed; abdominal segments cylindrical in cross-section.

Thoracic notopodia elongate, cirriform from setiger 1 ( Fig. 48 B), continuing through thoracic ( Fig. 50 B) and abdominal setigers; neuropodia swollen, bearing large fascicles of setae and a single fingerlike postsetal lobe from setiger 1 ( Fig. 48 B); abdominal neuropodia simple, bluntly rounded, bearing a short ventral cirrus ( Fig. 48 C); a distinct ventral flange present; interramal cirrus lacking.

Thoracic notosetae including 30–35 long, crenulated capillaries; abdominal notopodia with 15 or more capillaries and 5–6 furcate setae; furcate setae with unequal tynes having blunted, notched tips, tynes connected by row of fine needles appearing as a thin membrane in light microscopy, shaft with ribs along one edge ( Figs. 48 H, 49D), in SEM 6–7 needles on either side, merging with tynes; tynes with distinct openings on tips (see arrows, Fig. 50 E).

Thoracic neurosetae including 7–8 rows of numerous uncini and two rows of crenulated capillaries ( Fig. 50 C); uncini with ribbed shaft and a bluntly rounded tip bearing a terminal notch, appearing bifid in some angles; entire end of shaft and tip with distinct lateral flange appearing hood-like in certain views ( Figs. 48 D–G, 49 B–C, 50D), smaller specimens with tips of uncini appearing more notched, probably due to less wear ( Fig. 49 B–C); abdominal neurosetae including 1–2 thin protruding aciculae with curved blunted tips, sometimes with thin membranous mucron ( Fig. 48 I), and 5–6 thin crenulated capillaries.

Branchiae from setiger 4 on all specimens ( Figs. 48 A, 49A, 50A); branchiae small, conical at first, increasing in size rapidly over following setigers, becoming cirriform with broad base and tapering to pointed tip; branchiae on abdominal segments considerably larger than on thoracic segments, triangular in shape; branchiae heavily ciliated on both margins. Bases of abdominal branchiae close together, joined by low transverse ridge. Middle thoracic through anterior abdominal segments with pair of oval-shaped dorsal sense organs medial and anterior to branchial bases.

Remarks. Naineris grubei is closely related to N. furcillata in the shape of the prostomium, number of thoracic setigers, and distribution and form of the setae. The two species differ in that the notopodia of posterior thoracic and abdominal setigers in N. furcillata have a distinctly forked appearance, whereas in N. grubei the notopodium is simple and entire throughout. Both species have abdominal neuropodia with a short ventral cirrus. The main difference between N. grubei and other congeners is in the nature of the notched or bidentate tips of the thoracic neuropodial uncini.

The new collections provide an opportunity to expand the original descriptions of Gravier (1908, 1909). The number of thoracic setigers was reported to be 17 in the original description, while the specimens from the Lund University Chile Expedition always have 19–20. The branchiae consistently begin on setiger 4 in the Lund materials, whereas Gravier (1909) indicated that they began on setiger 7 on his specimen from Peru. The small oval dorsal sensory organs of thoracic and anterior abdominal setigers do not appear to have been reported previously. The difference in the number of thoracic setigers and position of the first pair of branchiae between the original account of Gravier (1908, 1909) and the new materials from Chile are likely due to size of the specimens. Graviers’ specimens were smaller, less than 5 mm long and with less than 50 segments. These correspond closely with small specimens considered to be juveniles and identified as N. cf. grubei by Blake (1996) from southern California where the number of thoracic setigers ranged from 8–13 and branchiae first occurred from setiger 5–6.

Naineris grubei australis Hartman, 1957 , an Australian species, was recently redescribed by Zhadan et. al. (2015). This subspecies, however, differs significantly from the stem form described here in having an entirely different kind of thoracic neuropodial uncini. In N. g rubei from South America, the thoracic neuropodial uncini have numerous transverse ribs on the shaft and a bluntly rounded tip bearing a terminal notch that apically appears bifid in most angles; a lateral flange is also present. In contrast, N. grubei australis has the transverse ribs and lateral sheath, but the notch is elongate and terminates in a smoothly rounded tip, not one that is bifid. In addition, Zhadan et al. (2015) report and illustrate subuluncini among the uncini of thoracic neuropodia of N. grubei australis . Subuluncini are not present in N. grubei reported in this study. For this reason, the subspecies from Australia should be raised to full species status: Naineris australis New Status.

Distribution. Ecuador, Peru, and Chile, intertidal to 25 m.

Figures

FIGURE 48. Naineris grubei (Gravier, 1908). Chile, Seno Reloneavi, Isla Tenglo, Sta. M 60 (SMNH 154440). A, anterior end, dorsal view; B, thoracic parapodium, anterior view; C, abdominal parapodium, posterior view; D – G, thoracic neuropodial uncini; H, furcate seta; I, abdominal neuropodial acicular seta.

FIGURE 49. Naineris grubei (Gravier, 1908), Chile, LUCE Seno Reloneavi, Isla Tenglo, Sta. M 60 (SMNH 154440). Juvenile. A, anterior end, dorsal view; B – C, thoracic neuropodial uncini; D, furcate seta.

FIGURE 50. Naineris grubei (Gravier, 1908). Chile, LUCE, Sta. M 45 (SEMs, JAB). A, Anterior end, dorsal view; B, thoracic setigers 4 – 13, in dorsal view; C, thoracic neuropodial uncini; D, detail of same; E, furcate seta, arrows denote opening on tips of tynes.