Epigamia, Nygren, Arne, 2004

Nygren, Arne, 2004, Revision of Autolytinae (Syllidae: Polychaeta)., Zootaxa 680, pp. 1-314 : 163-166

Epigamia gen. n.

Linnean name definition. Type species Autolytus noroi Imajima & Hartman, 1964 .

Node­based name definition. Epigamia refers to the least inclusive clade comprising E. noroi ( Imajima & Hartman, 1964) , and E. macrophtalma ( Marenzeller, 1875) .

Apomorphies. Morphologically supported by one apomorphy ( Fig. 4 ): 1) body ciliation as 2 trochs per segment (character 4), other most parsimonious reconstructions (MPRs) possible, character state change is a parallelism, later reversed within clade, character state unknown in E. labordai ( San Martín & López, 2002).

General description.

Atokous form. Length 1.8–22 mm for 20–88 chaetigers; width, measured at level of proventricle and excluding parapodial lobes, 0.2–1.5 mm. Body shape, excluding parapodial lobes, cylindrical to rounded rectangular in transection, venter flattened; body width fairly constant with tapering end. Ciliation as 1 or 2 trochs per segment (unknown in some taxa). Prostomium usually rounded rectangular, in E. macrophtalma more rounded oval. Four eyes, with lenses, in trapezoid arrangement, anterior pair larger. Eyes confluent or separated; eye spots absent or present. Palps fused at base or completely fused; in dorsal view projecting 1/5–1/2 of prostomial length. Extension of nuchal epaulettes from end of chaetiger 1 to end of chaetiger 6.

Prostomium with 3 antennae; median antenna inserted medially on prostomium, the lateral on anterior margin. Tentacular cirri 2 pairs. Dorsal cirri alternate in length, except in E. macrophtalma ; cirrophores equal; cirrophores shorter or equal in length to parapodial lobes. All appendages cylindrical except in E. macrophtalma with flattened dorsal cirri from chaetiger 3.

Parapodial lobes generally large, rounded to rounded rectangular; in some taxa with slightly swollen dorsal part. Except for bayonet chaetae, all chaetae compounds with bidentate blades; serration present. Compounds with small or large distal tooth. Single thin bayonet chaetae, subdistally denticulated.

Pharynx with single to multiple sinuations. Trepan with various types of denticulation, in 1–3 rings. Basal ring present; infradental spines absent or present. Proventricle with varying number of rows of square shaped muscle cells. Pygidium with 2 cirri (reported length compared to body width, excluding parapodial lobes, at level of proventricle, if not otherwise stated); median papilla absent.

Epitokes.

Male. Body divided into 3 regions, anterior with 11 (see E. noroi ) or 14 uniramous chaetigers (region a), median with c. 37 biramous chaetigers (region b), and posterior with 3–23 uniramous chaetigers (region c). Body widest in anteromedian half of region b; body width measured in region a, as body width excluding parapodial lobes, and in region b, at the widest part, as body width including parapodial lobes. Ciliation as in atokes.

Prostomium rounded rectangular, wider than long, with straight or concave anterior margin. Eyes large, 2 pairs, with lenses; eyes situated on dorsal and ventral side of prostomium, ventral pair larger. Palps present, much smaller than in atokes. Nuchal epaulettes as in atokes.

Large median antenna inserted medially on prostomium, lateral antennae inserted on anterior margin. Lateral antennae bifid, basal part c. 1/2 of total length; outer ventral rami equal or longer than inner dorsal rami. Basal part and inner dorsal rami segmented with abundant cilia. Pair of small frontal processes inserted anterolaterally to dorsal pair of eyes. Tentacular cirri as in atokes. First dorsal cirri, larger than in atokes, equal in shape and size to median antenna. Achaetous knobs absent. Cirri with alternation in direction and size in region a, and c as in atokes; cirri in region b with less obvious alternation in both size and direction. However, this needs to be explored using a larger sample­size. Cirri length measured as body width excluding parapodial lobes in region a, and c; as body width including parapodial lobes in region b. Median antenna with large ceratophore, large cirrophores present on first dorsal cirri; cirrophores otherwise as in atokes. Appendages cylindrical, suspected to be flattened in epitokes of E. macrophtalma .

Pharynx and proventricle disintegrates at some stage, and is totally absent in fully developed epitokes.

Neuropodia as in atokes but generally larger and with enlarged, and prolonged dorsal part, especially in region b; in region b also with well­developed flattened notopodial lobes. Neuropodial aciculae as in atokes; notopodia in region b supported by c. 3 anterodorsal aciculae, and 3–4 thick and 3–5 thin posteroventral aciculae. Neuropodial chaetae as in atokes. Notopodial lobes with 20–50 swimming chaetae, in length equal to c. body width in region b including parapodial lobes. Pygidium as in atokes.

Female. Body divided into 3 regions, anterior with 14 uniramous chaetigers (region a), median with 29–41 biramous chaetigers (region b), posterior with 16–33 uniramous chaetigers (region c). Body width fairly constant, slightly wider in region b; body width measured in region a, as body width excluding parapodial lobes, and in region b as body width including parapodial lobes. Ciliation as in atokes.

Prostomium rounded rectangular, wider than long, with straight or concave anterior margin. Eyes large, 2 pairs, with lenses; eyes situated on dorsal and ventral side of prostomium, ventral pair larger. Palps present, much smaller than in atokes. Nuchal epaulettes as in atokes.

Median antenna inserted medially on prostomium, lateral antennae inserted on anterior margin. Tentacular cirri as in atokes. Achaetous knobs absent. Cirri with alternation in direction as in atokes, except for cirri in region b with less obvious alternation; cirri length as in atokes or longer. Cirri length measured as body width excluding parapodial lobes in region a, and c; as body width including parapodial lobes in region b. Cirrophores as in atokes. Appendages cylindrical, suspected to be flattened in epitokes of E. macrophtalma .

Pharynx and proventricle disintegrates at some stage, and is totally absent in fully developed epitokes.

Neuropodia as in atokes but generally larger and with enlarged, and prolonged dorsal part, especially in region b; in region b also with notopodial lobes, not as developed as in male. Neuropodial aciculae as in atokes; notopodia in region b supported by 5–14 anterodorsal aciculae, and 6–8 thick and 6–9 thin posteroventral aciculae. Neuropodial chaetae as in atokes. Notopodial lobes with 25–50 swimming chaetae, in length equal to c. body width in region b including parapodial lobes. Pygidium as in atokes.

Epigamia alexandri ( Malmgren, 1867) comb. n. (Fig. 83A–G)

Autolytus alexandri Malmgren, 1867: 37 , pl. 7, fig. 39, 39C–D; Langerhans 1879, 577; Verrill 1881, 292, pl. 12, fig. 8, 8A–C; Okada 1937; Hartman 1945: 17; Pettibone 1954: 246 –247; 1963: 147–148, fig. 37F–G; Gidholm 1965: 36 –38; Hamond 1969b; 1974; Hartmann­Schröder 1971: 176;? Qian & Chia 1989; San Martín 1994: 271 –272, fig. 1A–D; Hartmann­Schröder 1996: 180 –181.

Autolytus newtoni Malmgren, 1867: 36 –37.

Stephanosyllis ornata Verrill, 1874a: 132 . 1874b: 361, pl. 4, fig. 1.

Autolytus longigula Verrill, 1881 : pl. 12, fig. 3, 3A–B.

Autolytus longeferiens Saint­Joseph, 1887: 217 –219, pl. 10, fig. 95–97; Southern 1914: 39 –40; Fauvel 1923: 319 –320, fig. 122H–K; Okada 1929a; Cognetti 1961: 304; Gidholm 1966; 1967: 201 –203, figs 2C, 7G, 13C, 27; Hartmann­Schröder 1971: 178; Kirkegaard 1992: 230 –231, fig. 112A–C; Hartmann­Schröder 1996: 183; Nygren & Sundberg 2003: GenBank sequences, 16S rDNA partial sequence AF474262 , and 18S rDNA partial sequence AF474308 .

Proceraea (Stephanosyllis) ornata Webster & Benedict 1887: 724 .

Autolytus longiferiens Elwes 1908: 202 ; Allen 1915: 604; McIntosh 1910: 245 –247, pl. 86, fig. 17, pl. 87, fig. 16.

Autolytus paradoxus Saint­Joseph, 1887: 216 –217, pl. 10, fig. 92–94; Fauvel 1923: 318, fig. 122E– F; Hartmann­Schröder 1971: 175.

Autolytus verrilli Marenzeller, 1892: 416 –420, pl. 19, fig. 4; Wesenberg­Lund 1947: 33 –36, figs 14–15; 1950: 52, fig. 13.

Proceraea rzhavskyi Britayev & San Martín, 2001 : 105–113, fig. 1A–E. Not figs 2–5.

Material examined. Greenland: holotype (female epitoke) SMNH 2438, West Greenland, Davis Strait, 65°N 60°W, Swedish arctic expedition 1859. Norway: holotype (female epitoke) of Autolytus newtoni SMNH 2437, Spitsbergen, Storfjord, 78°37'N 19°E, 21 Aug 1864. Russia: holotype ZMMSU 849, and 4 paratypes ZMMSU 850–853 of Proceraea rzhavskyi, Mednyy Island (Commander Islands), Gladkovskaya Bay, 54°44'N 167°45'E, 6 m, on hydroid Abietinaria turgida, 1986 . Faroes: 35 spms (15 spms in formalin, 18 spms on slide, 2 spms in author's collection for DNA analyses), South of Vagar, 61°56.8'N 06°59.5'W, triangle­dredge, 76–78 m, hydroids, 27 Jun 1997; 7 spms (1 spm in formalin, 6 spms in author's collection for DNA analyses), East of Nolsøy, 62°01.5'N 06° 31.9W, triangle dredge, 41 m, bedrock, 27 Jul 1997; 29 spms (17 spms in formalin, 9 spms on slides (2 rear ends in author's collection for DNA analyses), 3 spms in author's collection for DNA analyses), East of Bordøy, 62°24.6'N 06°26.3'W, triangle dredge, 65–68 m, shellgravel with hydroids, 17 Jul 1997; 7 spms (6 spms on slides, 1 in author's collection for DNA analyses), East of Bordøy, 62°08.4'N 06°23.4'W, triangle dredge, 77 m, shellgravel with hydroids, 17 Jul 1997. France: 11 syntypes of Autolytus longeferiens MNHN 1031–1041, Dinard, Jun–Aug 1872–1881; holotype of Autolytus paradoxus MNHN 1030, Dinard, 18 Jul 1887. USA: 8 spms (4 spms in formalin (2 rear ends in author's collection for DNA analyses), 2 spms on slides (rear ends in author's collection for DNA analyses), 2 spms in author's collection for DNA analyses), Rock Pt and López Island, 48°29.6'N 122°56.9'W, dredge, 75 m, Polycarpa sp., barnacles with rich hydroid fauna, few sponges, 24 Jan 2001.

Diagnosis. Epigamia with a DDU­group posterior to chaetiger 27, a much convoluted pharynx, and a trepan with 1 large teeth alternating with 2–4 much smaller.

Description. Length 4.5–17.2 mm for 27–88 chaetigers, width 0.20–0.72 mm. Live specimens from faint reddish or yellowish, sometimes with 3 faint red lines, to more intensely red anterior to proventricle, intestinal region orange to red­brown; anterior appendages red­tipped; eyes red. Preserved specimens without colours. Ciliation as 2 trochs per segment.

Eyes confluent (Fig. 83B); eye spots present. Palps in dorsal view projecting c. 1/3 of prostomial length. Nuchal epaulettes reaching between end of chaetiger 1 (small individuals), and end of chaetiger 2 (Fig. 83A, B).

Median antenna reaching chaetiger 7–15 (n=10) in live specimens. Lateral antennae and dorsal tentacular cirri, length 1/2–2/3 of median antenna. Ventral tentacular cirri 1/3– 1/2 as long as dorsal pair. First dorsal cirri as long as median antenna, second dorsal cirri as long as ventral tentacular cirri. From chaetiger 1–27 cirri with usual alternation in direction, followed by 1 DDU­groups, 1–3 DDUU­groups, and 1–13 DDU­groups (n=6). Dorsal cirri from chaetiger 3, alternate in length (Fig. 83A); short cirri equals 1/2–2/3 of body width, long cirri equal or slightly longer than body width. Cirrophores present on tentacular cirri, and all dorsal cirri. Cirrophores equal, cirrostyles unequal; short cirrostyles 1/2– 2/ 3 in length of long cirrostyles; cirrophores shorter than parapodial lobes; cirrophores shorter than cirrostyles. All appendages cylindrical.

Parapodial lobes large, rounded, slightly swollen dorsal to chaetal fascicle. 2–4 aciculae in anterior chaetigers, 1–2 in median and posterior. Chaetal fascicle with 9–18 compounds in anterior chaetigers, 3–13 in median and posterior. Compound chaetae with large distal tooth (Fig. 83F); serration present. Single thin bayonet chaetae (Fig. 83G), beginning between chaetiger 3–30.

Pharynx with from one sinuation (small individuals) anterior to proventricle to multiple sinuations anterior and lateral to proventricle (Fig. 83D). Trepan in chaetiger 1–4, with 34–44 unequal teeth, 9 large teeth and 25–35 smaller; 1 large alternating with 2–4 much smaller, in 2 rings, small teeth situated slightly inside large teeth (Fig. 83E). Basal ring present; infradental spines present (Fig. 83E). Proventricle equal in length to 2–4 segments in chaetiger 6–18 with 34–44 rows of muscle cells (n=11). Anal cirri equal in length to 1– 2 times the body width.

Reproduction. Epigamy (Fig. 83C, D). Epitokous specimens caught in February to May in the North Atlantic ( Hamond 1969b). Transforming individuals observed in January in the North Pacific (pers. obs.).

Figures

FIGURE 4. Character transformations. Symbols as follow: black box, only one most parsimonious reconstruction (MPR) exists; white box, more than one MPR exist; X reversal; = parallelism; character later reversed within clade; character further changed within clade;? unknown character state for one or several taxa within clade.