Lamispina milligani, Salazar-Vallejo, 2014

Salazar-Vallejo, Sergio I., 2014, Revision of Pherusa Oken, 1807 (Polychaeta: Flabelligeridae), Zootaxa 3886 (1), pp. 1-61 : 54-56

Lamispina milligani n. sp.

Figure 24

? Pherusa (sic).— Milligan, 1984:47.16, Fig. 47.12a–e.

Type material. Northwestern Atlantic, Florida. Holotype ( MCZ 1034 ), South of Dry Tortugas, RV Blake 1877–78, Sta. 43 (24°08' N, 82°51' W), 620 m, no date, A. Agassiz, coll.

Description. Holotype (MCZ 1034) includes an anterior and a posterior fragment, cylindrical, tapered posteriorly ( Fig. 24A ); first three chaetigers depressed, following ones swollen, wider; 7 mm long, 2.5 mm wide,

cephalic cage 4 mm long, 12 chaetigers (posterior fragment 18 mm long, 1.5 mm wide, 20 chaetigers). Tunic thin, finely papillated, with sediment particles, woolly, mostly detached from anterior region. Body papillae small, digitate, about 2 transverse series per segment, small along dorsal and ventral surfaces ( Fig. 24B ).

Cephalic hood exposed, short, margin smooth (damaged). Prostomium low cone; eyes not seen. Caruncle short, triangular. Palps lost; palp keels low, rounded. Lateral lips large, projected, distally paler. Ventral and dorsal lips fused to lateral lips ( Fig. 24C ).

Branchiae cirriform, arranged in a single row; 8 filaments decreasing in size laterally. Size relationship with palps unknown. Nephridial lobes small, barely projected, between branchiae 2 and 3, counting from the middorsal line.

Cephalic cage chaetae mostly broken, longest remaining chaetae less than twice as long as body width. Chaetigers 1–3 forming cephalic cage. Cephalic cage chaetae arranged in short series, ventrolateral. Number of chaetae in cephalic cage unknown; neuropodium 3 with 12 multiarticulated, long chaetae.

Anterior dorsal margin of first chaetiger with a medial lobe projected anteriorly, margin crenulated (another similar projection on the ventral margin of chaetiger 1). Chaetigers 1–3 decreasing in length, increasing in width posteriorly; notopodia with long conical lobes. Chaetal transition from cephalic cage to body chaetae abrupt; lamispines from chaetiger 4. Gonopodial lobes not seen.

Parapodia poorly developed, transverse low folds (posterior fragment damaged), chaetae emerge from body wall. Parapodia lateral; medial neuropodia ventrolateral. Notopodia long conical lobes directed anteriorly in chaetigers 1–3, then low lateral lobes, without special papillae. Neuropodial lobes low, without special papillae. Noto- and neuropodia close to each other.

Medial notochaetae arranged in transverse tufts; all multiarticulated capillaries, articles short basally, mediumsized medially, long distally ( Fig. 24D ); about 10 per fascicle, as long as 1/3 body width. Neurochaetae multiarticulated capillaries in chaetigers 1–3; lamispines from chaetiger 4, yellowish, arranged in transverse series, or in inverted C- or J-patterns, 8 in chaetiger 4, 9 thereafter (posterior fragment with 7–8 lamispines per fascicle). Lamispines in medial chaetigers with margins entire ( Fig. 24E ), becoming hirsute or plumose by lateral fragmentation of individual fibers in more posterior chaetigers ( Fig. 24F ).

Posterior end unknown.

Etymology. This species is named after Michael R. Milligan for his contributions to the Taxonomic Guide to the Polychaetes from the Northern Gulf of Mexico, because he wrote the chapter on flabelligerids ( Milligan 1984), and because he noticed that some of his specimens did not fit into Pherusa because of the long neurohooks, and very long notochaetae. Regretfully, his material was not found and its affinities to this species cannot be determined. The epithet is a noun in the genitive case.

Remarks. Lamispina milligani n. sp. can be grouped with L. falcata (Støp-Bowitz, 1948) n. comb. and L. schmidtii ( Annenkova-Chlopina, 1924) n. comb. because their bodies have delicate, filiform papillae, which can be eroded leaving bare surfaces. However, L. milligani is unique within the group because it has very short notochaetae (1/3 as long as body width), and because its lamispines have tips with fibers exposed. The specimen is very old and this exposure of chaetal fibers might be regarded as a physical degradation but this roughness resembles what can be seen in some other deep-water flabelligerids, such as Ilyphagus ( Salazar-Vallejo 2012d) , and by analogy, this feature is regarded as species specific. The differences between L. falcata and L. schmidtii were indicated previously.

Type locality. Florida Strait .

Distribution: Apparently restricted to the Florida Strait, in soft bottoms at 620 m depth. If Milligan’s juvenile specimens belonged to this species, then it would be present along the Northern Gulf of Mexico, in silty clay at 134 m depth.

Figures

FIGURE 24. Lamispina milligani n. sp., holotype (MCZ 1034), stained with methyl green. A. Anterior and posterior fragments; anterior fragment in dorsal view. B. Same, anterior end, ventral view. C. Head, branchiae and palps removed (BS: branchial scar, PS: palp scar). D. Chaetiger 11, right parapodium (inset medial notochaetal region). E. Posterior fragment, anterior chaetiger, lamispines (inset: tip). F. Same, posterior chaetiger, lamispine (inset: tip). Scale bars: A: 1.9 mm, B: 0.6 mm, C, D: 0.2 mm, E: 150 µm, F: 100 µm.