Comprehensive Description

provided by Smithsonian Contributions to Zoology
Malmgreniella nigralba (E. Berkeley, 1923)

Malmgrenia nigralba E. Berkeley, 1923:213, pl. l: figs. 5–7; 1924:193.—Berkeley and Berkeley, 1941:21; 1942:187; 1948:10. fig. 8.—Pettibone, 1967:3.—Hartman. 1968:133, figs. 1–3.—Kudenov, 1975b:77, 79.

Harmothoe lunulata.—Hartman, 1944:244 [part]; 1968:81 [part]. [Not Delle Chiaje. 1830.]

Malmgrenia lunulata.—Pettibone, 1953:25, pl. 9: fig. 77; pl. 10: figs. 80–82, 85, 87: pl. 11: figs. 96–103 [part].—Banse et al., 1968:525 [part].—Lie, 1968:303, 370, 371 [part: sta 5]. [Not Delle Chiaje, 1830.]

Harmothoe nigralba.—Hanley, 1987:153, fig. 3F,H.

MATERIAL EXAMINED.—EASTERN PACIFIC OCEAN: British Columbia: Vancouver Island, Piper's Lagoon, near Nanaimo, very low tide, sandy, 20 Jun 1920, E. Berkeley, collector, 3 syntypes (USNM 32875–6). Pipers's Lagoon, 21 May 1924, coarse gravelly sand, commensal in vertical burrows of Leptosynapta clarki Heding. E. Berkeley, collector, 2 specimens (USNM 55040). Washington: Puget Sound, Seattle, Golden Gardens Park, shore, with Leptosynapta clarki Heding, 7 May 1949, M. Pettibone, collector, 2 specimens (USNM 55041). Olalla, shore, 22 Jun 1939, M. Pettibone, collector, 1 specimen (USNM 24931). Gig Harbor, shore, 3 Aug 1944, J.E. Lynch, collector, 2 specimens (USNM 24926). Near Dutchers Cove, Case Inlet, shore, gravelly, shelly sand, with L. clarki, 21 Jun 1947. 6 Jun and 17 Aug 1948. M. Pettibone, collector, 18 specimens (USNM 24925, as M. lunulata var. nigralba by Pettibone, 1953). Southwest of Johnson Point, Case Inlet, 47°10′N, 122°50′W, 15–36 m, coarse shelly sand mixed with rock and many L clarki, sta 5, 12 Feb 1963, U. Lie, collector, 3 specimens (USNM 36444, as M. lunulata form A by Banse et al., 1968). California: Tomales Bay, sandy-mud, with Lepto synapta clarki, summer 1941, F. Pitelka and R. Paulson, collectors, 2 specimens (USNM 24929; AHF 1202, as H. eurosetae with bifid tips [Figure 48H] H. lunulata by Hartman, 1944). Off Santa Cruz Island, 9–27 m, summer 1939, W.G. Hewatt, collector, 1 specimen (USNM 55042, as M. nigralba by Berkeley and Berkeley, 1941).

DESCRIPTION.—Syntypes all fragmented. Complete syntype, in 2 pieces (USNM 32876), 14 mm long, 5 mm wide including setae, and 40 segments, posterior segment very small. Adult specimens from Case Inlet (USNM 24925) 18–24 mm long, 5–7 mm wide, with 37–40 segments; small specimen 7.5 mm long, 3 mm wide, with 30 segments.

Body showing striking black and white pigmentation; both dorsal and ventral sides of posterior segments showing dark pigmentation. Elytra 15 pairs, on usual segments, circular to subreniform, with group of microtubercles on anterior medial part; microtubercles absent on 1st pair and some posterior elytra (Figure 39B–D). Pigmentation on elytra somewhat variable. On syntypes from Nanaimo and specimens from Tomales Bay, 1st pair of elytra with complete circle of dark pigmentation and large reticular area (Figure 39B); following elytra with reticular area confined to posterior two-thirds up to near border, with some scattered microtubercles, and complete or nearly complete oval ring of dark pigmentation (Figure 39C,D; Berkeley, 1923, pl. 1: figs. 6, 7). Melanistic specimens from Case Inlet dark gray on most of posterior two-thirds of elytra, including borders; reticular area with scattered microtubercles, circle of darker color around central colorless area, and group of microtubercles on anterior medial part (absent on first pair and more posterior elytra) (Figure 40A–D; Pettibone, 1953, pl. 11: figs. 96, 98–100).

Bilobed prostomium with anterior lobes truncate, without peaks; anteroventral pair of eyes slightly larger than posterodorsal pair, ceratophore of median antenna bulbous, in anterior notch, style with minute papillae, slightly longer than prostomium; ceratophores of lateral antennae inserted terminoventrally, converging midventrally, with styles short, subulate, papillate; palps stout, tapered; tentaculophores lateral to prostomium, with 0–1 seta on inner side; dorsal and ventral tentacular cirri similar to median antenna (Figure 39A; Berkeley, 1923, pl. 1: fig. 5; Pettibone, 1953, pl. 11: figs. 96, 97; Hanley, 1987, fig. 3F,H).

Segment 2 with 1st pair of large elytrophores, biramous parapodia, and long ventral buccal cirri similar to tentacular cirri (Figure 39A,E); notosetae similar to following notosetae; neurosetae more slender than those following, with bulbous tips, upper and lower ones entire, middle ones with secondary tooth (Figure 39F). Extended pharynx with 9 pairs of border papillae and 2 pairs of hooked jaws.

Biramous parapodia with smaller notopodium rounded, with projecting acicular lobe on lower side; larger neuropodium with subconical presetal acicular lobe with digitiform or tapered supraacicular process and slightly shorter rounded postsetal lobe (Figure 39E,G,H; Pettibone, 1953, pl. 11: fig. 101). Notosetae moderate in number, about same width as neurosetae, short to longer, smooth or with faint spinose rows (Figure 39I). Neurosetae moderate in number, upper ones with longer spinose region, upper few with rounded blunt tip, some with small secondary tooth; middle ones with shorter spinose region, hooked tip with distinct secondary tooth; lower ones with entire rounded tip or with small tooth (Figure 39J; Pettibone, 1953, pl. 11: figs. 102, 103). Dorsal cirri with cylindrical cirrophore with glandular area on posterior side; style with short clavate papillae, tapered distally and extending to about tips of neurosetae; dorsal tubercles nodular; ventral cirri short, subulate, with small papillae (Figure 39H). Pygidium with anus medial to last pair of small parapodia, with pair of anal cirri.

BIOLOGY.—Malmgreniella nigralba was found in the Nanaimo area, Vancouver Island by Edith Berkeley in coarse gravelly sand living commensally in the vertical burrows of the synaptid Leptosynapta clarki Heding (as L. inhaerens) and by M. Pettibone in the Puget Sound area. In Tomales Bay, Central California, M. nigralba also was found associated with L. clarki (as L. albicans) by F. Pitelka and R. Paulson.

DISTRIBUTION.—Eastern Pacific Ocean from British Columbia to Central California, in low water to 36 meters.
bibliographic citation
Pettibone, Marian H. 1993. "Scaled polychaetes (Polynoidae) associated with ophiuroids and other invertebrates and review of species referred to Malmgrenia McIntosh and replaced by Malmgreniella Hartman, with descriptions of new taxa." Smithsonian Contributions to Zoology. 1-92. https://doi.org/10.5479/si.00810282.538