Pherusa aspera ( Stimpson, 1854 )

Salazar-Vallejo, Sergio I., 2014, Revision of Pherusa Oken, 1807 (Polychaeta: Flabelligeridae), Zootaxa 3886 (1), pp. 1-61 : 17-19

Pherusa aspera ( Stimpson, 1854)

Figure 4

Siphonostomum asperum Stimpson, 1854:31 .

Trophonia aspera .— Moore, 1909b:143.

Pherusa aspera .— Appy et al., 1980:33, Fig. 61.— Trott 2004:288 (both informal n. comb.).

Type material. Northwestern Atlantic Ocean. Neotype ( USNM 8889 ), Bay of Fundy , 1872, A.E. Verrill, coll.

Additional materials. Northeastern Atlantic Ocean. One specimen ( USNM 8950), anterior fragment, broken in two, off Cape Ann, Massachusetts, RV Speedwell, Sta. 157, 73 m, 15 Aug. 1878, A.E. Verrill, id. as T. aspera . One specimen ( USNM 8957), complete, broken posteriorly, regenerating posterior end, off Cape Cod, Massachusetts, RV Speedwell, Sta. 292, 53 m, 11 Aug. 1879, A.E. Verrill, id. as T. aspera (35 mm long, 4 mm wide, cephalic cage 9 mm long, 50 chaetigers; 10 notochaetae and 5 neurohooks in chaetiger 10). One specimen ( USNM 8960), complete, posterior region slightly collapsed, off Cape Cod, Massachusetts, RV Speedwell, Sta. 322, 123 m, 1 Sep. 1879, A.E. Verrill, id. as T. aspera (30 mm long, 2 mm wide, cephalic cage 7 mm long, 69 chaetigers). One specimen ( USNM 8961), without posterior end, anterior end slightly exposed, off Cape Cod, Massachusetts, RV Speedwell, Sta. 376, 84 m, 26 Sep. 1879, A.E. Verrill, id. as T. aspera . One specimen ( USNM 8962), anterior fragment, depressed, some papillae damaged, off Cape Cod, Massachusetts, RV Speedwell, Sta. 378, 176 m, 26 Sep. 1879, A.E. Verrill, id. as T. affinis (16 mm long, 5 mm wide, cephalic cage 9 mm long, 26 chaetigers). One specimen ( USNM 16177), anterior fragment, damaged, anterior end exposed, used for description, Grand Manan, New Brunswick, 1872, no further data, A. E. Verrill, id. as T. aspera . One specimen ( USNM 16178), anterior fragment, damaged, papillae eroded, off Whitehead, Nova Scotia, RV Bache, Sta. UU’, 51–95 m, 23 Aug. 1872, A. E. Verrill, id. as T. aspera . Two specimens ( USNM 19538), complete, without field data (34–38 mm long, 3–4 mm wide, cephalic cage 8–9 mm long, 63–65 chaetigers; 5 notochaetae and 3–4 neurohooks in chaetiger 10). Four specimens ( USNM 23262), one complete and three large, anterior fragments, Red Bay, Labrador, RV Blue Dolphin, 15 m, soft mud, 30 Jun. 1949, D.C. Nutt, coll., M. Pettibone, id. as Pherusa plumosa (complete specimen 38 mm long, 4 mm wide, cephalic cage 8 mm long, 71 chaetigers; only sand grains on dorsal papillae; 7 notochaetae and 4 neurohooks in chaetiger 10).

Description. Neotype (USNM 8889) without posterior end; body cylindrical, anteriorly swollen, slightly tapered medially and posteriorly ( Fig. 4A ), distally swollen, damaged, body wall broken in several places; 29 mm long, 2 mm wide, cephalic cage 5 mm long, 47 chaetigers. Papillae with sand particles dorsally, especially along anterior third of body, less abundant posteriorly (probably eroded). Papillae arranged in 5–6 alternating transverse series; ventral papillae smaller, without sediment particles ( Fig. 4B ).

Cephalic hood not exposed; not dissected to avoid further damage (anterior end features observed in USNM 8957). Prostomium low cone, medially furrowed; four black eyes, anterior ones larger. Caruncle short. Palps twice as thick as, and slightly shorter than branchiae; palp keels rounded, low. Dorsal and lateral lips well developed, ventral lip reduced ( Fig. 4C ).

Branchiae cirriform; four branchiae arranged in a single row, proximal branchiae separated into two lateral pairs. Nephridial lobes short, conical, placed under the superior, proximal branchia.

Cephalic cage chaetae 2.5x longer than body width. Chaetigers 1–3 forming cephalic cage; chaetae arranged in short series, dorsal in chaetiger 1, dorsolateral in chaetigers 2–3. Chaetiger 1 with 10 noto- and 7 neurochaetae, chaetiger 2 with 9 noto- and 6 neurochaetae, chaetiger 3 with 9 noto- and 6 neurochaetae.

Anterior dorsal margin of first chaetiger smooth barely projected. Chaetigers 1–3 progressively longer. Chaetal transition from cephalic cage to body chaetae abrupt; anchylosed, falcate blunt neurohooks from chaetiger 4. Gonopodial lobes not seen.

Parapodia poorly developed, chaetae emerge from body wall. Parapodia lateral; medial neuropodia ventrolateral. Notopodial lobes low with one pre- and two longer postchaetal papillae. Neuropodial lobes lower with one anterior, two posterior, and an inferior long papillae.

Medial notochaetae arranged in a È-pattern, transverse to body axis, directed dorsally. All notochaetae multiarticulated capillaries, articles short basally, medium-sized medially, longer distally ( Fig. 4D ), 7–8 per fascicle, as long as body width throughout the body. Neurochaetae multiarticulated capillaries in chaetigers 1–3; falcate anchylosed neurohooks from chaetiger 4, arranged in transverse series ( Fig. 4E ), 5–6 throughout the body.

Posterior end missing. Other specimens with posterior region blunt, without long chaetae; pygidium with terminal anus lacking anal cirri.

Neotype locality. Bay of Fundy , Canada.

Variation. The available specimens showed a narrow range of variation being 30–38 mm long, 2–4 mm wide, cephalic cage 7–9 mm long, 50–69 chaetigers.

Remarks. Pherusa aspera ( Stimpson, 1854) is redefined because it has been confused with other species in the area, particularly P. plumosa ( Müller, 1776) . These two species are similar but differ because in P. aspera , dorsal papillae are covered by sand grains resulting in irregular, rough tubercles, whereas in P. plumosa the dorsal papillae are covered by fine sediment particles, resulting in smooth tubercles. The presence of sand particles is more evident in smaller specimens of P. aspera , like the neotype, since a single particle might block the whole dorsal papilla, but in larger specimens the dorsal surface looks rough, or aspera , the Latin word for granulate.

The taxonomic status of P. aspera needs clarification because there are other similar species along Northwestern Atlantic coasts. The proposal of a neotype together with its description and illustrations will clarify its taxonomic definition ( ICZN 1999, Art. 75.3.1–75.3.3). The original material was deposited in the Smithsonian Institution but later transferred to Chicago in 1866, when William Stimpson was appointed director of the local Academy of Sciences, but destroyed in 1871 during the great Chicago fire (http://www.si.edu/oahp/ ScientificIllustrators/WStimpson.html; ICZN 1999, Art. 75.3.4). This species can easily be identified by using a key to the local fauna ( Appy et al. 1980), such that the neotype can be confidently regarded as belonging to the species ( ICZN 1999, Art. 75.3.5). The original type locality was Hake Bay, off Bay of Fundy, Maine, in shelly bottoms, 46 m. The neotype was collected in the same bay but, regretfully, no further field data were attached to the specimen; however, the neotype was collected near to the type locality ( ICZN 1999, Art. 75.3.6), and it has been deposited in the National Museum of Natural History, Smithsonian Institution ( ICZN 1999, Art. 75.3.7).

As stated above, P. aspera belongs in the group of species with dorsal body papillae encrusted with sand particles. This group also includes P. andersonorum n. sp., P. incrustata Quatrefages, 1866 reinst., P. neopapillata Hartman, 1961 , and P. obscura Quatrefages, 1849 reinst. However, P. aspera and P. andersonorum n. sp., are the only species with sand particles present on all body papillae. They differ in the relative number of neurohooks in medial and posterior chaetigers. In P. aspera there are 5–6 neurohooks per bundle (body 2 mm wide), whereas P. andersonorum n. sp., has fewer neurohooks per bundle (3–4; body 2.8 mm wide). A further difference is the habitat for each species and although there is little detailed information about P. aspera , it occurs in shelly bottoms in depths to 45 m ( Appy et al. 1980:33), whereas P. andersonorum lives in dead kelp holdfasts in subtidal rocky bottoms.

Distribution. Cape Cod to Labrador, in variable sediments of moderate depths (15–192 m).

Figures

FIGURE 4. Pherusa aspera (Stimpson, 1854). A. Neotype (USNM 8889), anterior region, dorsal view. B. Same, ventral view. C. Another specimen (USNM 8957), head, frontal view (branchiae and palps removed; BS: branchial scar, LL: lateral lip, PS: palp scar). D. Neotype, chaetiger 10, right notopodium (inset: chaetal tips). E. Same, chaetiger 9, neurochaetae (two smaller neurochaetae not shown). Scale bars: A, C: 0.7 mm, B: 0.9 mm, D: 225 µm, E: 112 µm.