Pherusa affinis ( Leidy, 1855 )

Salazar-Vallejo, Sergio I., 2014, Revision of Pherusa Oken, 1807 (Polychaeta: Flabelligeridae), Zootaxa 3886 (1), pp. 1-61 : 13-15

Pherusa affinis ( Leidy, 1855)

Figure 2

Siphonostomum affine Leidy, 1855:148 .

Trophonia affinis .— Verrill, 1873:507–508, Pl. 14, Fig. 75 (Reprinted 1874:311–312, Pl. 14, Fig. 75).

Pherusa affinis .— Gosner, 1978:194, Fig. 53.— Appy et al., 1980:33, Fig. 60 (both informal n. comb.).

Neotype material. Northwestern Atlantic Ocean . Neotype ( USNM 8882 ) and 13 paratypes ( USNM 1251742 ), one complete, off Point Judith (41°21'39" N, 71°28'53" W), Rhode Island, USFC Fish Hawk , Sta. 784, 12 Aug. 1880, sand, gravel and shell fragments, 20 m (complete paratype 32 mm long, 2 mm wide, cephalic cage 4.5 mm long, 75 chaetigers; small anterior fragment with a spongy tunic covering the back of chaetigers 1–2) .

Additional material. Northwestern Atlantic Ocean. One anterior fragment ( MCZ 55669), Wiscasset, Maine, 6 Jun. 1966, T. Creaser, coll. Five specimens, one complete ( USNM 8898 ), Buzzards Bay , Massachusetts, USFC Fish Hawk, Sta. 1221, 11– 16 m, 10 Aug. 1881. Eleven specimens, one complete ( USNM 9119 ), off Newport, Rhode Island , USFC Fish Hawk, Sta. 795, 35 m, 14 Aug. 1880 (19.5 mm long, 1.5 mm wide, cephalic cage 4 mm long, 57 chaetigers). Twenty-five specimens ( USNM 9429 ), USFC Fish Hawk, Sta. 772, off Beaver Tail Lighthouse, 15 m, 6 Aug. 1880 (anterior fragments, dried-out). One specimen ( USNM 23256 ), without posterior region, off Bridgeport, Connecticut, 7 Sep. 1889, M.H. Pettibone, id. Three specimens ( USNM 40214 ), chaetae broken, body papillae eroded, one complete, Clam Harbour, Nova Scotia, Canada, 27 Jun. 1958, J.C. Medcof, coll. (complete 75 mm long, 5 mm wide, cephalic cage 8.5 mm long, 79 chaetigers). Eight specimens ( USNM 57662 ), three complete, three anterior fragments, one medial and one posterior fragments, Cape Cod Bay , Massachusetts, Biotic Census Sta. 2224C, 18-20 m, 27 Mar. 1969, C.D. Long, id. (complete ones 83–108 mm long, 4.0– 8.5 mm wide, cephalic cage 15.0– 15.5 mm long, 77–89 chaetigers). One anterior fragment ( USNM 1260293 ), Cape Hatteras, North Carolina, 1963, M. Cerame-Vivas, coll .

Description. Neotype (USNM 8882), complete, body cylindrical, tapered, posterior region swollen, blunt; 44 mm long, 3 mm wide, cephalic cage 6 mm long, 80 chaetigers. Papillae with fine sediment particles, a few capitate, most rounded, digitate, lobate ( Fig. 2A ), some depressed ( Fig. 2C ), arranged transversally to body axis, especially on anterior chaetigers: most papillae small, abundant, giving the surface a velvety appearance, larger dorsally. Larger digitate papillae along chaetal lobes and over the anterior dorsal margin of chaetigers 1–5, making a single, transverse series.

Cephalic hood short, margin smooth. Prostomium low cone; four dark brown eyes, anterior ones larger, posterior ones smaller. Caruncle short. Palps large, longer than branchiae; palp keels rounded. Lateral lips narrow, well developed ( Fig. 2D ); ventral lip reduced; dorsal lip rounded.

Branchiae cirriform, thick, four arranged in a row, barely separated dorsally; two of them (third ones counting from top) displaced slightly inner to the others. Palps longer than branchiae; all branchiae of the same length and width.

Cephalic cage chaetae about as long as 1/5 body length, over 2.5x longer than body width. Chaetigers 1–3 forming cephalic cage. Chaetae arranged as short series, dorsolateral in chaetiger 1, lateral in chaetigers 2–3. Chaetiger 1 with 7–8 chaetae per ramus, chaetiger 2 with 6–7, and chaetiger 3 with 5–6 chaetae per ramus.

Anterior dorsal margin of first chaetiger papillated, papillae digitate. Chaetigers 1–3 (sometimes up to chaetiger 5) with longer digitate papillae on anterior segment margins and chaetal lobes, arranged in 1–2 transverse series on the latter. Chaetigers 1–3 increasing in size posteriorly. Chaetal transition from cephalic cage to body chaetae abrupt; anchylosed, falcate blunt neurohooks start in chaetiger 5. Gonopodial lobes present in chaetigers 5–6 (– 7 in largest anterior fragment, USNM 8898), transverse short slits, close to neuropodia, visible after brushing off papillae, reduced to flat lenticular areas, becoming long behind neurochaetal lobes after body contraction.

Parapodia poorly developed, reduced low chaetal lobes; chaetae emerge from the body wall. Parapodia lateral; medial neuropodia ventrolateral. Notopodia with two series of long digitate papillae, prechaetal ones smaller, not continued towards the neuropodia. Neuropodia less developed with similar papillar arrangement to notopodia.

Medial notochaetae arranged in short oblique series; all notochaetae multiarticulated capillaries, articles short basally, becoming medium-sized medially and distally ( Fig. 2E ), 8–10 (12 in largest specimen) per fascicle, as long as 1/3 body width. Neurochaetae multiarticulated capillaries in chaetigers 1–4; simple falcate neurohooks from chaetiger 5, superior one twice as large as others, arranged in transverse series, 3 in anterior chaetigers ( Fig. 2F ), up to 4 in medial chaetigers, reduced to 3 in posterior chaetigers.

Posterior end slightly swollen, blunt; pygidium short, conical; anus dorsoterminal, without cirri.

Variation. Complete specimens were 19.5–108.0 mm long, 1.5–8.5 mm wide, cephalic cage 4.0– 15.5 mm long, 57–89 chaetigers. Three neurohooks per row in anterior chaetigers, four in medial ones; superior one largest, twice as large as the others (invariable). Five anterior chaetigers with long parapodial and middorsal papillae.

Remarks. Siphonostomum affine Leidy, 1855 was briefly described and although it is apparently well defined and understood being frequently recorded in some benthic ecology or regional studies (e.g., Gosner 1978:194, Appy et al., 1980:33, Steimle & Terranova 1991:10, Pollock 1998:181, Trott 2004:288), it must be defined by the proposal of a neotype and its redescription including illustrations to clarify the taxonomic status of the species ( ICZN 1999, Art. 75.3.1–75.3.3). Joseph Leidy had a very productive life as a scientist, became president of the Academy of Natural Sciencies of Philadelphia ( Chapman 1891:348), and worked during 46 years in it ( Osborn 1913:342). His main legacy is in palaeontology and parasitic worms ( Walton 1927), the latter being part of the socalled Joseph Leidy Collection: parasitic organisms (Nemata, Nematomorpha), but his other specimens apparently were not deposited in the corresponding institution. Consequently, there is no type material available ( ICZN 1999, Art. 75.3.4). The description of the neotype and its corresponding illustrations help discriminate the species from similar ones ( ICZN 1999, Art. 75.3.5). The neotype was collected about 400 km away from the original type locality, but the regional oceanographic conditions are similar along this Northwestern Atlantic region, especially along the shore between type and neotype localities ( Townsend et al. 2006). Consequently, the neotype and other regional specimens are believed to be conspecific ( ICZN 1999, Art. 75.3.6), and have been deposited in the National Museum of Natural History, Smithsonian Institution ( ICZN 1999, Art. 75.3.7).

Pherusa affinis ( Leidy, 1855) groups with five other species due to their papillae being relatively clean with little or no sediment cover; however, P. affinis can be distinguished from the other species by having neurohooks from chaetiger 5.

Neotype locality. Off Point Judith (41°21'39" N, 71°28'53" W), Rhode Island, sand, gravel and shell fragments, 20 m depth. The original type locality was Beesley’s Point, New Jersey (39°16'36" N, 74°38'11" W), about 400 km along the Northeastern United States shore.

Distribution. From the Bay of Fundy to Cape Hatteras, in intertidal and shallow water muddy bottoms, 11-35 m depth.

Figures

FIGURE 2. Pherusa affinis (Leidy, 1855), paraneotypes (USNM 1251742). A. Anterior end, dorsal view. B. Same, ventral view. C. Non-type specimen (USNM 40214), anterior end, oblique dorsal view. D. Same, head, frontal view (branchiae and palps removed; BS: branchial scar, LL: lateral lip, PS: palp scar). E. Another paraneotype (USNM1251742), chaetiger 10, right notopodium (insets: basal and medial chaetal regions). F. Same, chaetiger 21, right neuropodium (insets: neurochaetal tips). Scale bars: A: 0.80 mm, B: 0.76 mm, C: 1.2 mm, D: 0.70 mm, E: 110 µm, F: 100 µm.