Myrianida flava, Nygren, Arne, 2004

Nygren, Arne, 2004, Revision of Autolytinae (Syllidae: Polychaeta)., Zootaxa 680, pp. 1-314 : 130-136

Myrianida flava sp. n. (Fig. 63A–G)

Autolytus sp1 Nygren & Sundberg 2003: GenBank sequences, 16S rDNA partial sequence AF474254 , and 18S rDNA partial sequence AF474300 .

Material examined. USA: holotype ( SMNH 5952) and 13 spms (6 spms in formalin, 6 spms on slides (5 rear end in author's collection for DNA analyses), 1 spm in author's collection for DNA analyses, Washington, San Juan Island, 48°32.7' N 123°00.8'W, epifauna on floating dock outside Friday Harbor laboratory, sponges, hydroids, barnacles, 22 Jan 2001; 2 paratypes ( SMNH 5953, 5954) (female and male epitokes), Washington, San Juan Island, 48°32.73'N 123°00.75'W, collected with light on floating dock outside Friday Harbor laboratory, Jan 2001.

Diagnosis. Myrianida with saffron­yellow colour; long alternating dorsal cirri with equal cirrophores, and unequal cirrostyles; trepan with 17–30 unequal teeth irregularly arranged.

Description. Length in live specimens 3.1–6.2 mm for 44–55 chaetigers, width 0.25– 0.4 mm. In life, bright yellow to orange (Fig. 63A, B); anterior appendages red­tipped; eyes deep red (Fig. 63B). Ciliation as 1 troch per segment.

Eyes confluent (Fig. 63B); eye spots present. Palps in dorsal view projecting 1/3 of prostomial length (Fig. 63B), fused. Extension of nuchal epaulettes to between beginning of chaetiger 4 and end of chaetiger 5 (Fig. 63B).

Median antenna reaching chaetiger 11–14 (n=2). Lateral antennae and dorsal tentacular cirri, length 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 dorsal tentacular cirri. From chaetiger 1–27 cirri with usual alternation in direction, followed by 3–4 DDUU­groups and 1–2 DDU­groups (n=3). Dorsal cirri from chaetiger 3 alternate in length (Fig. 63A); short cirri slightly shorter or equal to body width, long cirri 1–1.5 times body width; chaetiger 4 sometimes with extra long dorsal cirri (Fig. 63A), almost equal in length to dorsal tentacular cirri. Cirrophores present on tentacular cirri, and all dorsal cirri. Cirrophores equal, cirrostyles unequal; short cirrostyles c. 2/ 3 in length of long cirrostyles; cirrophores equal in length to parapodial lobes; cirrophores shorter than cirrostyles. All appendages cylindrical.

Parapodial lobes rounded, of medium size. Anterior chaetigers with 1–3 aciculae, 1–2 in median and posterior. Chaetal fascicle with 8–10 compounds in anterior chaetigers, 4–8 in median and posterior. Compound chaetae with small distal tooth; serration present (Fig. 63D). Single thin bayonet chaetae (Fig. 63E), beginning between chaetiger 10–15.

Pharynx with sinuation anterior to proventricle. Trepan in chaetiger 2–4, with 17–30 unequal teeth; irregularly sized and irregularly arranged, in 1 ring (Fig. 63C). Basal ring present; infradental spines absent. Proventricle equal in length to 5–6.5 segments (Fig. 63B) in chaetiger 8–17 with 38–44 rows of muscle cells. Anal cirri equal in length to c. body width (Fig. 63A).

Reproduction. By schizogamy, most likely by posterior scissiparity. As indication to this are several specimens with newly regenerating posterior ends.

Morphology of epitokous stages.

Male. Length in live specimens 3.9–4.7 mm for 3+(23–26)+(4–8) chaetigers (n=5), width in region a 0.2–0.3 mm, width in region b 0.6–0.8 mm. Live specimens yellow, without colour markings (Fig. 63G). Ciliation as in stock.

Prostomium with concave anterior margin (Fig. 63G). Nuchal epaulettes rounded triangular, extending to beginning of chaetiger 1 (Fig. 63G).

Median antenna reaching middle of region b, c. chaetiger 8–10. Lateral bifid antenna, 1.5 times as long as prostomial width. Basal part 1/3 of total length, outer ventral rami 2 times longer than inner dorsal rami. Frontal processes, equal to 1/3 of prostomial width. Pair of small processes inserted immediately ventral to lateral antennae and proximal to ventral eyes (prostomial ventral processes), present in 3 out of 5 specimens. Tentacular cirri 1 pair (Fig. 63G), as long as 2/3 of prostomial width. First dorsal cirri, equal in length to median antenna. Achaetous knobs absent. Cirri on chaetiger 1 equal to 1.5 times body width, cirri on chaetiger 2 and 3 shorter (Fig. 63F), equal to body width; cirri in region b slightly shorter than in a, reciprocally equal, measuring 1/4 of body width; cirri in region c equals 1/4 of body width. Median ceratophore, small cirrophores on tentacular cirri, large cirrophores on first dorsal cirri, small cirrophores in region a, present; otherwise cirrophores absent. All appendages cylindrical (Fig. 63G).

Single neuropodial acicula in all chaetigers; 2 anterodorsal, and 3 thick and 3 thin posteroventral notopodial aciculae in region b. Neuropodial chaetal fascicle with 3–8 compounds; single thin bayonet chaetae beginning at chaetiger 1. Notopodial chaetal fascicle with 15–20 swimming chaetae. Anal cirri equal in length to cirri in region c.

Female. Length in preserved specimen 6 mm for 6+23+15 chaetigers (n=1), width in region a 0.3 mm, width in region b 0.7 mm. Live specimens yellowish orange without colour markings, eggs yellow (Fig. 63F).

Prostomium with straight anterior margin. Nuchal epaulettes rounded–triangular, extending to half of chaetiger 1 (Fig. 63F).

Median antenna reaching chaetiger 4–5. Lateral antennae, 2/ 3 in length of median antenna. Tentacular cirri 2 pairs, ventrally positioned, both pair equal to prostomial width. First dorsal cirri, about equal in length to following dorsal cirri, situated above first chaetigerous lobe. Achaetous knobs absent. Cirri in region a equal to 2 times body width; cirri in region b longer than in a, equal in length to body width; cirri in region c shorter than in b, about equal to body width. Cirrophores present on all dorsal cirri (Fig. 63F), equal in length to parapodial lobes in region a; tentacular cirrophores not possible to detect. All appendages cylindrical (Fig. 63F).

Single neuropodial acicula in all chaetigers; 2 anterodorsal, and 3 thick and 3 thin posteroventral notopodial aciculae in region b. Neuropodial chaetal fascicle with 3–8 compounds; single bayonet chaetae beginning at chaetiger 1. Notopodial chaetal fascicle with c. 15 swimming chaetae. Anal cirri equal in length to dorsal cirri in region c.

Habitat. 0–1 m, amongst rich epifauna, sponges, barnacles, hydroids.

Distribution. North East Pacific. Washington. Only known from type locality.

Etymology. Flava is latin and means yellow, named after its bright yellow­orange colour.

Remarks. Myrianida flava is easily identified when alive, its bright yellow­orange colour and long dorsal cirri is striking. Compared with other Myrianida it is relatively sluggish, and when disturbed the specimens coil up towards the back, much like in M.

inermis . In the molecular analysis M. flava group together with M. inermis , M. dentalia , and M. pentadentata Imajima, 1966 . M flava is distinguished from all these taxa in a number of characters, including its trepan with irregularly sized and arranged trepan teeth.

Myrianida hesperidium ( Claparède, 1868) comb. n. (Fig. 64A–F) Autolytus hesperidium Claparède, 1868: 526 –529, pl. 14, fig. 1, 1A–K; Nygren & Sundberg 2003: GenBank sequences, 16S rDNA partial sequence AF474259 , and 18S rDNA partial sequence AF474305 .

Autolytus tyrrhenicus Cognetti, 1953c: 123 –127, fig. 2; 1957: 72–73, fig. 16A–B.? Autolytus hesperidium Webster 1879: 225 –226.

Material examined. France: 20 spms (9 spms in formalin, 8 spms on slides (6 rear ends in author's collection for DNA analyses), 3 spms in author's collection for DNA analyses), Banyuls­sur­Mer, 42°28.8'N 03°08.1'E, docks in harbour, 1 m, mussels, sponges, hydroids, 19 Apr 2001.

Diagnosis. Myrianida with short equal cirrophores and equal cirrostyles; trepan with 12–13 equal triangular teeth, and a thin basal ring.

Description. Length 3.1–5.5 mm for 30–50 chaetigers, width 0.18–0.25 mm. Live specimens uncoloured to faintly yellowish (Fig. 64A), intestinal region greenish to yellowish with white specks from intestinal granular accumulations; eyes red. Ciliation as 1 troch per segment.

Eyes separated (Fig. 64A); eye spots present. Palps in dorsal view projecting 1/4–1/3 of prostomial length (Fig. 64A), fused. Extension of nuchal epaulettes to between end of chaetiger 2 and end of chaetiger 3 (Fig. 64A).

Median antenna reaching chaetiger 9–11 (n=6). Lateral antennae and dorsal tentacular cirri, length 1/2–2/3 of median antenna. Ventral tentacular cirri 1/2 as long as dorsal pair. First dorsal cirri, length 2/3 of median antenna, second dorsal cirri as long as ventral tentacular cirri, 1.5 times longer than following cirri. From chaetiger 1–27 cirri with usual alternation in direction followed by 3–4 DU­groups and 2–3 DDUU­groups (n=4). Dorsal cirri from chaetiger 3, of equal length, 1/2 of body width (Fig. 64A). Cirrophores present on tentacular cirri, and all dorsal cirri. Cirrophores and cirrostyles equal; cirrophores shorter than parapodial lobes; cirrophores shorter than cirrostyles. All appendages cylindrical (Fig. 64A).

Parapodial lobes rounded, of medium size. Anterior chaetigers with 2 aciculae, 1 in median and posterior. Chaetal fascicle with 7–14 compounds in anterior chaetigers, 3–8 in median and posterior. Compound chaetae with small distal tooth; serration present (Fig. 64E). Single thin bayonet chaetae (Fig. 64F), beginning between chaetiger 1–11 (n=6).

Pharynx with 1, often twisted, sinuation anterior and lateral to anterior half of proventricle (Fig. 64A). Trepan in chaetiger 2–3, with 12 (n=6) or 13 (n=1) equal teeth, arranged in 1 ring (Fig. 64D). Thin basal ring present; infradental spines present (Fig. 64D). Proventricle equal in length to 2–3 segments in chaetiger 8–11 with 24–25 rows of muscle cells (n=4). Anal cirri equal in length to 1–1.5 times body width.

Reproduction. Schizogamous reproduction by gemmiparity behind chaetiger 26 (Cognetti's specimen) or chaetiger 30. Stolon­bearing specimens found all year round, but mostly from Mars to May ( Cognetti 1957).

Morphology of epitokous stages.

Male. Length in preserved specimens 1.8–2.0 mm for 3+16+(0–1) chaetigers (n=3), width in region a 0.15 mm, width in region b 0.3 mm. Live specimens faintly greenish, without colour markings (Fig. 64C).

Prostomium with concave anterior margin (Fig. 64C). Nuchal epaulettes rounded, extending to beginning of chaetiger 1 (Fig. 64C).

Median antenna reaching middle of region b, c. chaetiger 9–11. Lateral bifid antennae, 2–3 times as long as prostomial width. Basal part 1/6 of total length, outer ventral rami 4– 5 times longer than inner dorsal rami (Fig. 64C). Frontal processes, equal to 1/3 of prostomial width. Tentacular cirri 1 pair (Fig. 64C), as long as 1–1.5 times prostomial width. First dorsal cirri, equal in length to median antenna. Achaetous knobs absent. Cirri in region a slightly longer or equal in length to body width, cirri on chaetiger 1 slightly longer than cirri on chaetiger 2 and 3 (Fig. 64C); cirri in region b shorter than in a, reciprocally equal, measuring 1/4 of body width. Median ceratophore, small tentacular cirrophores, large cirrophores on first dorsal cirri, present; cirrophores otherwise absent. All appendages cylindrical (Fig. 64C).

Single neuropodial acicula in all chaetigers; 2 anterodorsal, and 2 thick and 3 thin posteroventral notopodial aciculae in region b. Neuropodial chaetal fascicle with c. 10 compounds in all chaetigers; single bayonet chaetae beginning at chaetiger 1. Notopodial chaetal fascicle with c. 15 swimming chaetae. Anal cirri equal in length to cirri in region a.

Female. Length of one preserved specimen 3.4 mm for 6+14+5 chaetigers, width in region a 0.2 mm, width in region b 0.35 mm. Live specimens without colour markings, eggs yellow (Fig. 64B).

Prostomium with straight anterior margin (Fig. 64B). Nuchal epaulettes rounded triangular, extending to beginning of chaetiger 1.

Median antenna reaching chaetiger 4. Lateral antennae, 2/ 3 in length of median antenna. Tentacular cirri 1 pair (Fig. 64B), 2/ 3 in length of lateral antennae. First dorsal cirri, equal in length to following dorsal cirri (Fig. 64B), situated above first chaetigerous lobes. Achaetous knobs absent. Cirri equal along whole specimen, equal to 3/4 of body width excluding parapodial lobes (Fig. 64B). Small cirrophores on tentacular cirri, and short equal cirrophores on all dorsal cirri, present. All appendages cylindrical.

Single neuropodial acicula in all chaetigers; 2 anterodorsal, and 2–3 thick and 2 thin posteroventral notopodial aciculae in region b. Neuropodial chaetal fascicle with c. 10 compounds in all chaetigers; single thin bayonet chaetae beginning at chaetiger 1. Notopodial chaetal fascicle with c. 15 swimming chaetae. Anal cirri equal in length to dorsal cirri.

Habitat. Intertidal, shallow waters, amongst hydroids, bryozoans, sponges.

Distribution. Mediterranean Sea.

Remarks. The identity of the present specimens as Myrianida hesperidium is concluded from the detailed description of Claparède, with which the specimens agree in every detail, except for the number of anal cirri that Claparède stated to be 4, and of 2 kinds; this is interpreted as a malformation in Claparède's specimen. Myrianida hesperidium has not been reported since the original description except for Websters 1879, and has probably been confused with other species. Websters' specimens probably belong to another taxon, but his description is not sufficient for a reliable identification. Myrianida hesperidium is most closely related to M. quindecimdentata , and also very similar to M. convoluta but the pharynx is not as convoluted as in the latter species and it lacks the brilliant white antenna characteristic for the former species. The trepans for these three taxa are very similar, and the number of teeth overlap to some extent between the species; M. convoluta has either 9 or 15–16 teeth, M. quindecimdentata has between 12 and 24, while M. hesperidium has 12 or 13. The synonomy of A. tyrrhenicus is based on the description, and may seem to be problematic. Cognetti stated that his A. tyrrhenicus has ten teeth, but in the figure there are 11, and that it always reproduce by gemmiparity behind chaetiger 26. However these differences are not considered sufficient to keep the taxa separate, as the actual number of teeth may be difficult to count, and that it is most likely that the stolonization zone may show some variation and not be limited to the same segment. Future studies may though relieve that M. hesperidium and A. tyrrhenicus are separate taxa with different stolonization segments.

Myrianida inermis ( Saint­Joseph, 1887) comb. n. (Fig. 65A–E)

Autolytus inermis Saint­Joseph, 1887: 237 –238, pl. 12, fig. 117; Elwes 1908: 202; McIntosh 1910: 247 –248, pl. 86, fig. 18, pl. 87, fig. 17; Allen 1915: 606; 1927: 874; Okada 1937; Cognetti 1961: 304 –305; Gidholm 1965: 34; 1967: 193–195, figs 7D–E, 22A–B; Hartmann­Schröder 1971: 177; Kirkegaard 1992: 227 –228, fig. 110A–C; Hartmann­Schröder 1996: 182 –183; San Martín 2003 (in part): 487–489, fig. 267A; Nygren & Sundberg 2003: GenBank sequences, 16S rDNA partial sequence AF474256 , and 18S rDNA partial sequence AF474302 . Autolytides inermis Malaquin 1893: 76 ; Southern 1914: 43.

Autolytus (Autolytides) inermis Fauvel 1923: 322 , fig. 123H–K.

Material examined. France: 2 syntypes of A. inermis on slides NMNH 1061–1062, Dinard, Jul 1881 –1882. Faroes: 13 spms (12 spms in formalin, 1 spm on slide), East of Bordøy, 62°04,6'N 06°26,3'W, triangle­dredge, 65–68 m, shellgravel with hydroids, 7 Jul 1997; 5 spms (3 spms in formalin (1 rear end in author's collection for DNA analyses), 1 spm on slide (rear end in author's collection for DNA analyses), 1 spm in author's collection for DNA analyses), East of Nolsøy, 62°01.5'N 06°31.9'W, triangle­dredge, 41 m, bedrock, 27 Jun 1997; 1 spm on slide (rear end 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; 1 spm on slide (rear end in author's collection for DNA analyses), East of Bordøy, 62°08.4'N 06°23.4'W, triangle­dredge, 65–68 m, shellgravel, 7 Jul 1997. USA: 5 spms (1 spm on slide, 4 spms in author's collection for DNA analyses), California , pier outside Scripps Institution of Oceanography, 32°N 117°W, dive, 7 m, algae and epifauna, 7 Jan 2001; 4 spms (1 spm on slide, 3 spms in author's collection for DNA analyses), Washington, Rock point and López Island, 48°29.6'N 122° 56.9W, dredge, 70–80 m, Polycarpa sp, barnacles with associated fauna, 24 Jan 2001. Norway: 1 spm (rear end in author's collection for DNA analyses), Trondheim, 63°28.36' N 10°00.04'W, m, shells, dead Lophelia , gravel, Jan 2002.

Diagnosis. Myrianida with poorly developed teeth, pharynx with many sinuations; dorsal cirrophores inflated, cirrostyles attached subterminal on cirrophores.

Description. Length 1.4–6.9 mm for 23–53 chaetigers, width 0.2–0.3 mm. Live specimens uncoloured to reddish or yellowish in pharyngeal region (Fig. 65A, B), intestinal region yellowish to brownish with scattered white and yellow specks from intestinal granular accumulations; tips of anterior appendages sometimes reddish; eyes red. Ciliation as 1 troch per segment.

Eyes rather large, almost confluent (Fig. 65A, B); eye spots present. Palps in dorsal view projecting 1/4–1/3 of prostomial length (Fig. 65A), fused. Extension of nuchal epaulettes from half of chaetiger 2 to beginning of chaetiger 4 (Fig. 65B).

Median antenna reaching chaetiger 8–15 (n=12). 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 1–1.5 times the ventral tentacular cirri. From chaetiger 1–27 cirri with usual alternation in direction, followed by 1–7 DDUU­groups, and 1 DDU­group (n=5). Dorsal cirri from chaetiger 3 of equal length (Fig. 65A), 1/2–2/3 of body width. Cirrophores present on tentacular cirri, and all dorsal cirri. Cirrophores and cirrostyles equal; cirrophores inflated (Fig. 65B), equal in length to parapodial lobes; cirrophores shorter than cirrostyles; cirrostyles attached subterminal to cirrophores (Fig. 65B). All appendages cylindrical.

Parapodial lobes rounded, of medium size. Anterior chaetigers with 2 aciculae, 1 in median and posterior. Chaetal fascicle with 9–14 compounds in anterior chaetigers, 3–8 in median and posterior. Compound chaetae with small distal tooth (Fig. 65D); serration present. Single thin bayonet chaetae (Fig. 65E), beginning between chaetiger 1–13.

Pharynx with several sinuation anterior and lateral to anterior half of proventricle (Fig. 65B). Trepan in chaetiger 1–3, with 2–7 low separated diffuse teeth with or without sinusoid waves teeth, arranged in 1 ring (Fig. 65C). Basal ring absent; infradental spines absent (Fig. 65C). Proventricle equal in length to 1.5–2.5 (Fig. 65B) segments in chaetiger 7–13 with 20–23 rows of muscle cells (n=14). Anal cirri c. twice as long as body width.

Reproduction. Schizogamous reproduction by posterior scissiparity behind chaetiger 19, 22, 26 or 30. Stolon­bearing specimens found from May to December ( Gidholm 1967).