Myrianida Milne Edwards 1845
- Dataset
- Revision of Autolytinae (Syllidae: Polychaeta).
- Rank
- GENUS
Classification
- kingdom
- Animalia
- phylum
- Annelida
- class
- Polychaeta
- order
- Phyllodocida
- family
- Syllidae
- genus
- Myrianida
description
Description. Holotype incomplete, length 0.6 mm for 9 segments, width 0.15 mm. Preserved material brownish, no colour markings. Body ciliation as 1 intrasegmental band per segment. Eyes separated; eye spots absent. Palps in dorsal view projecting 1 / 4 – 1 / 3 of prostomium length, fused. Extension of nuchal epaulettes to end of tentacular segment. Median antenna reaching chaetiger 5. Lateral antennae and first dorsal cirri, length 1 / 2 of median antenna. Dorsal tentacular cirri, length 2 / 3 of lateral antennae. Ventral tentacular cirri 1 / 2 as long as dorsal pair. Alternation in direction of cirri not assessed. Cirri from chaetiger 2 of equal length (Fig. 59 A), 1 / 2 of body width. 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. Parapodial lobes rounded, of medium size. All chaetigers with 1 – 2 aciculae. Chaetal fascicle with c. 10 compound chaetae. Compound chaetae with small distal tooth; serration present (Fig. 59 B). Single thin bayonet chaetae (Fig. 59 C), beginning at chaetiger 3. Pharynx with short sinuation anterior to the proventricle. Trepan in chaetiger 1, with 20 – 25 equal teeth, difficult to assess. Basal ring present (uncertain observation), infradental spines may be present, difficult to assess. Proventricle equal in length to 2 segments in chaetiger 4 – 5 with c. 23 rows of muscle cells. Posterior part lost. Reproduction. Unknown. Habitat. Algae with sand.
description
Description. Holotype is a budding specimen with two developing stolons (Fig. 58 A), incomplete, length of stock 2.2 mm for 23 chaetigers, width 0.2 mm. Preserved material yellowish brown, no colour markings. Ciliation not possible to assess. Eyes separated; eye spots present. Palps in dorsal view projecting c. 1 / 3 of prostomial length (Fig. 58 A). Extension of nuchal epaulettes to end of chaetiger 1. Anterior appendages and most dorsal cirri lost. Alternation in direction of cirri not assessed. Dorsal cirri from chaetiger 3, alternate in length; short cirri slightly shorter than 1 / 2 body width, long cirri slightly longer than 1 / 2 body width. Cirrophores on tentacular segment and all dorsal cirri present. Cirrophores equal, cirrostyles unequal (Fig. 58 B, C); short cirrostyles 2 / 3 in length of long cirrostyles; cirrophores longer than parapodial lobes; cirrophores on short cirri longer than cirrostyles (Fig. 58 B), cirrophores on long cirri equal in size to cirrostyles (Fig. 58 C). Appendages cylindrical, including lost lateral antennae and tentacular cirri (Winternitz 1936). Parapodial lobes rounded, of medium size. Anterior chaetigers with 2 – 3 aciculae, 1 in median and posterior. Chaetal fascicle with 10 – 12 compounds in anterior chaetigers, 5 – 8 in median and posterior. Compound chaetae with small distal tooth; serration present (Fig. 58 E). Single thin bayonet chaetae (Fig. 58 F), beginning at chaetiger 1. Pharynx with sinuation anterior and lateral to anterior half of proventricle. Trepan in chaetiger 2 with 26 – 30 equal teeth (Fig. 58 D). Basal ring thin, distinct; small infradental spines present (Fig. 58 D). Proventricle equal in length to 3 segments in chaetiger 5 – 8, with 28 – 30 rows of muscle cells. Reproduction. Schizogamous reproduction by gemmiparity behind chaetiger 23. Habitat. Unknown.
description
Description. Holotype is a rear fragment, description is based on the paratype. Paratype incomplete, length 1.5 mm for 22 chaetigers, width 0.1 mm. Preserved material without colour markings. Ciliation not possible to assess. Eyes separated; eye spots absent. Palps in dorsal view projecting 1 / 5 of prostomial length, fused. Extension of nuchal epaulettes to half of chaetiger 1. Median antenna reaching c. chaetiger 8. Lateral antennae and dorsal tentacular cirri, length 1 / 2 of median antenna. Ventral tentacular cirri 1 / 2 as long as dorsal pair. First dorsal cirri as long as median antenna, second dorsal cirri as long as following dorsal cirri. Alternation in direction of cirri not assessed. Dorsal cirri from chaetiger 3, of equal length, 1 / 3 of body width. Cirrophores present on tentacular cirri, and all dorsal cirri. Cirrophores and cirrostyles equal; cirrophores much shorter than parapodial lobes; cirrophores shorter than cirrostyles. All appendages cylindrical. Parapodial lobes rounded, of medium size. Single acicula in all chaetigers. Chaetal fascicle with 5 – 6 compounds in all chaetigers. Compound chaetae with small distal tooth; serration present. Single thin bayonet chaetae present in all chaetigers. Pharynx with 1 sinuation anterior to proventricle. Trepan in chaetiger 3 – 4, with c. 18 equal teeth, arranged in 1 ring (Fig. 55 A). Basal ring moderately to well developed; infradental spines present (Fig. 55 B). Proventricle equal in length to 1.5 segments (Fig. 55 C) in chaetiger 7 – 8 with c. 20 rows of muscle cells. Pygidium (holotype) has lost its cirri. Reproduction. Unknown Habitat. Intertidal, under stones.
description
Description. Length 1.7 – 2 mm for 31 – 45 chaetigers, width 0.2 mm. Preserved material whitish, no colour markings. Ciliation not possible to assess. Eyes separated (Fig. 56 B); eye spots present. Palps in dorsal view projecting 1 / 4 – 1 / 3 of prostomial length (Fig. 56 A), fused. Extension of nuchal epaulettes to end of chaetiger 3 (Fig. 56 B). Median antenna lost. Lateral antennae reaching chaetiger 7 – 9. Tentacular cirri and first dorsal cirri lost. Cirri on chaetiger 2 equal in length to body width. From chaetiger 1 – 27 cirri with usual alternation in direction, more posterior difficult to assess. Dorsal cirri from chaetiger 3 alternate in length; short cirri equals 1 / 2 of body width, long cirri equals 3 / 4 of body width. Cirrophores present on tentacular cirri, and all dorsal cirri. Cirrophores equal, cirrostyles unequal; short cirrostyles c. 2 / 3 in length of long cirrostyles; cirrophores shorter than parapodial lobes; cirrophores shorter than cirrostyles. Appendages cylindrical, including lost median antenna (HartmannSchröder 1982). Parapodial lobes rounded, of medium size. Single acicula in all chaetigers. Chaetal fascicle with 5 – 7 compounds in all chaetigers. Compound chaetae with small distal tooth; serration present (Fig. 56 E). Single thin bayonet chaetae (Fig. 56 D), beginning at chaetiger 4. Pharynx with from one to several sinuations anterior and lateral to anterior half of proventricle (Fig. 56 A). Trepan in chaetiger 1 (Fig. 56 B), with 16 – 18 equal teeth (Fig. 56 C), arranged in 1 ring. Thin distinct basal ring; infradental spines present (Fig. 56 C). Proventricle equal in length to 3 – 5 segments in chaetiger 8 – 13 (Fig. 56 A) with 25 – 27 rows of muscle cells. Anal cirri lost. Reproduction and morphology of epitokous stage. Schizogamy. The holotype of Autolytus devaneyi has 4 regenerating posterior chaetigers (Fig. 56 A) that possibly represent a developing stolon. HartmannSchröder briefly describes stolons that she refers to Myrianida australiensis. Male stolons with (2 – 3) + (13 – 15) + 0 chaetigers, for 1.13 mm, female stolons with 25 chaetigers, swimming chaetae in posterior chaetigers only (possibly immature). Habitat. Amongst algae, in intertidal zone.
description
Description. Length 1.7 – 2.6 mm for 22 stock chaetigers, length including stolons 3.2 – 5.9 mm; width 0.15 – 0.20 mm. Live specimens uncoloured to faintly yellowish, intestinal region yellowish with white specks from intestinal granular accumulations (Fig. 60 A), small orange glands present across each segment, especially in cirrophores; eyes red. Ciliation as 1 troch per segment. Eyes separated; eye spots present. Palps do not project in front of prostomium (Fig. 60 B), fused. Extension of nuchal epaulettes to between end of chaetiger 1 and end of chaetiger 2 (Fig. 60 B). Median antenna reaching chaetiger 6 – 8 (n = 2). 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 following dorsal cirri (Fig. 60 B). Alternation in direction of cirri not assessed. Dorsal cirri from chaetiger 3, of equal length (Fig. 60 B), c. 1 / 2 of body width. 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. 60 A, B). Parapodial lobes rounded, of medium size. Single acicula in all chaetigers. Chaetal fascicle with 5 – 7 compounds in anterior chaetigers, 2 – 6 in median and posterior. Compound chaetae with small distal tooth; serration present. Single thin bayonet chaetae, beginning between chaetiger 1 – 15. Pharynx with many sinuations anterior to proventricle (Fig. 60 B). Trepan in chaetiger 1 – 2, with 9 or 15 – 16 equal teeth, in 1 ring (Fig. 60 C). Thin basal ring present; infradental spines present (Fig. 60 C). Proventricle equal in length to 1.5 – 2.5 segments (Fig. 60 B) in chaetiger 7 – 12 with 19 – 21 rows of muscle cells (n = 4). Anal cirri equal in length to body width. Reproduction. Schizogamous reproduction by gemmiparity behind chaetiger 22. Stolonbearing specimens occur all year round but mostly in May to January (Cognetti 1957). Morphology of epitokous stages. Male. Length in preserved specimen 1.8 mm for 3 + 14 + 0 chaetigers (n = 1), width in region a 0.15 mm, width in region b 0.3 mm. Live specimens faintly greenish, without colour markings (Fig. 60 D). Ciliation as in stock. Prostomium without straight anterior margin. Nuchal epaulettes rounded, extending to beginning of chaetiger 1. Median antenna reaching middle of region b, c. chaetiger 8. Lateral bifid antennae, 3 times as long as prostomial width; basal part 1 / 5 of total length, outer ventral rami 4 – 5 times longer than inner dorsal rami (Fig. 60 D). Frontal processes, equal to 1 / 5 of prostomial width. Tentacular cirri 1 pair (Fig. 60 D), as long as 1 – 1.5 times prostomial width. First dorsal cirri, 2 / 3 as long as 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; 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 long cirri, short cirrophores on cirri in region a, present; cirrophores otherwise absent. All appendages cylindrical (Fig. 60 D). Single neuropodial acicula in all chaetigers; 2 anterodorsal, and 2 thick and 3 thin, posteroventral notopodial aciculae in region b. Neuropodial chaetal fascicle with 5 – 10 compounds; single thin bayonet chaetae beginning at chaetiger 1. Notopodial chaetal fascicle with c. 15 swimming chaetae. Anal cirri equal in length to 2 times body width. Female. No fully developed stolons examined. Habitat. Intertidal and subtidal, amongst hydroids, bryozans, and tunicates.
description
Description. Length 3.8 – 8.9 mm for 30 – 70 chaetigers, width 0.25 – 0.44 mm. Live specimens uncoloured to faintly yellowishorange (Fig. 57 A – B), intestinal region often with scattered white specks from intestinal granular accumulations; tips of anterior appendages often reddish; eyes orangered. Ciliation as 1 troch per segment. Eyes separated (Fig. 57 A); eye spots present. Palps in dorsal view projecting 1 / 3 – 1 / 2 of prostomial length (Fig. 57 A), fused. Extension of nuchal epaulettes to between end of chaetiger 1 and end of chaetiger 2 (Fig. 57 A). Median antenna reaching chaetiger 9 – 16 (n = 19). 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 as long as median antenna, second dorsal cirri as long as ventral tentacular cirri. From chaetiger 1 – 27 cirri with usual alternation in direction (Fig. 57 A, B), followed by 2 – 6 DDUUgroups, and a varying number of DDU, DUU, and DMUgroups (n = 17). Dorsal cirri from chaetiger 3 alternate in length; short cirri equals 2 / 3 – 3 / 4 of body width, long cirri equal to or slightly longer than body width. Cirrophores present on tentacular cirri, and all dorsal cirri. Cirrophores and cirrostyles unequal; cirrophores and cirrostyles on short cirri 2 / 3 in length of its counterpart in long cirri; cirrophores on short cirri equal to or slightly longer than parapodial lobes, cirrophores on long cirri longer than parapodial lobes; cirrophores shorter than cirrostyles. All appendages cylindrical (Fig. 57 B). Parapodial lobes rounded, medium to large in size. Anterior chaetigers with 2 – 3 aciculae, 1 in median and posterior. Chaetal fascicle with 10 – 15 compounds in anterior chaetigers, 4 – 9 in median and posterior. Compound chaetae with small distal tooth; serration present (Fig. 57 D). Single thin bayonet chaetae (Fig. 57 E), beginning at chaetiger 6 – 20. Pharynx with sinuation anterior to proventricle (Fig. 57 A). Trepan in chaetiger 2 – 4, with 22 – 29 unequal teeth; 8 (n = 1), 9 (n = 11) or 10 (n = 2) large and 14 – 21 smaller; 1 large alternating with 1 – 3 smaller, arranged in 1 ring (Fig. 57 C). Basal ring present; infradental spines present (Fig. 57 C). Proventricle equal in length to 3 – 4.5 segments in chaetiger 8 – 14 with 30 – 39 rows of muscle cells (n = 21). Anal cirri equal in length to 1 – 1.5 times body width. Reproduction. Schizogamous reproduction by gemmiparity behind chaetiger 34 – 88. Stolonbearing specimens observed from June to October, but not in January and May, in Scandinavian waters (Gidholm 1967). Freeswimming stolons occur in plankton from April to November in the Atlantic (Hamond 1974). Morphology of epitokous stages. Male. Length in preserved specimens 3.4 – 3.7 mm for 3 + (23 – 24) + 0 chaetigers (n = 3), width in region a 0.2 mm, width in region b 0.6 mm. Live specimens faintly greenish, without colour markings. Ciliation as in stock. Prostomium with concave anterior margin. Nuchal epaulettes rounded, extending to beginning of chaetiger 1. Median antenna reaching middle of region b (chaetiger 10 – 12). Lateral bifid antennae, 2 – 3 times as long as prostomial width; basal part 1 / 2 of total length, rami of about equal size. Frontal processes, equal to 1 / 3 of prostomial width. Tentacular cirri 1 pair, as long as prostomial width. First dorsal cirri, equal in length to median antenna; achaetous knobs absent. Cirri on chaetiger 1 equal to body width, cirri on chaetiger 2 and 3 shorter, equal to 3 / 4 of body width. Cirri in region b shorter than in a, reciprocally equal, measuring c. 1 / 4 of body width. Median ceratophore, small cirrophores on tentacular cirri, large cirrophores on first dorsal cirri, and short cirrophores in region a, present; cirrophores otherwise absent. Cirri in region a cylindrical to fusiform, cirri in region b fusiform, frontal processes slightly club shaped, other appendages cylindrical. Single neuropodial acicula in all chaetigers; 2 anterodorsal, and 2 thick and 2 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 1 – 2 times body width. Female. Based on female stolons of Autolytus mirabilis. Length in preserved specimen c. 3 mm for 2 + (15 – 18) + (0 – 2) chaetigers (n = 18), width in region a 0.3 mm, width in region b 0.7 mm. Prostomium with concave anterior margin. Nuchal epaulettes rounded – triangular, reaching beginning of chaetiger 1. Median antenna reaching chaetiger 3. Lateral antennae, 2 / 3 in length of median antenna. Tentacular cirri 1 or 2 pairs. 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 body width; cirri in region b slightly longer than in a; cirri in region c tapering towards the posterior end. Cirrophores present on all dorsal cirri, equal in length to parapodial lobes in region a; tentacular cirrophores not possible to detect. All appendages cylindrical. Single neuropodial acicula in all chaetigers; 2 anterodorsal, and 2 thick and 3 thin posteroventral notopodial aciculae in region b. Neuropodial chaetal fascicle with 4 – 5 compounds; single bayonet chaetae beginning at chaetiger 1. Notopodial chaetal fascicle with c. 15 swimming chaetae. Anal cirri lost. Habitat. From low intertidal, but mostly subtidal. Amongst hydroids, bryozans, and tunicates. Fed successfully in laboratory experiments with Laomedea dichotoma var. plana, L. gelatinosa, and L. loveni (Hamond 1969 c).
description
Description. Length in live specimens 3.0 – 8.2 mm for 22 – 43 stock chaetigers, length including stolons up to 13 mm, width 0.28 – 0.45 mm. Body sides, particularly in pharyngeal region, reddish, otherwise uncoloured to faintly yellowishorange (Fig. 62 A, B), intestinal with a more or less intense white middorsal line from intestinal granular accumulations (Fig. 62 A); tips of anterior appendages often reddish; eyes red. Ciliation as 1 troch per segment. Eyes separated; eye spots present (Fig. 62 B). Palps in dorsal view projecting 1 / 3 of prostomial length (Fig. 62 B), fused. Extension of nuchal epaulettes to between beginning of chaetiger 1 and beginning of chaetiger 2 (Fig. 62 B). Median antenna reaching chaetiger 7 – 11 (n = 12) in live specimens. Lateral antennae and dorsal tentacular cirri, length 2 / 3 of median antenna. Ventral tentacular cirri 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 – 3 DDUUgroups, and 1 – 4 DDUgroups (n = 10). Dorsal cirri from chaetiger 3, of subequal length (Fig. 62 A), 1 / 2 – 2 / 3 of body width. Cirrophores present on tentacular cirri and all dorsal cirri. Cirrophores and cirrostyles equal; cirrophores slightly shorter, or equal to parapodial lobes; cirrophores shorter than cirrostyles. All appendages cylindrical (Fig. 62 A). Parapodial lobes rounded, of medium – large size. Anterior chaetigers with 2 – 3 aciculae, 1 – 2 in median and posterior. Chaetal fascicle with 10 – 19 compounds in anterior chaetigers, 4 – 12 in median and posterior. Compound chaetae with small distal tooth; serration present. Single thin bayonet chaetae, beginning between chaetiger 1 – 22. Pharynx with sinuation anterior to proventricle. Trepan in chaetiger 1 – 3, with 24 – 34 equal teeth, arranged in 1 ring (Fig. 62 E). Basal ring present; infradental spines present (Fig. 62 E). Proventricle equal in length to 2 – 2.5 segments in chaetiger 6 – 10 with 23 – 31 rows of muscle cells (n = 16). Anal cirri equal in length to 1 – 2 times body width. Reproduction. Schizogamous reproduction by gemmiparity (Fig. 62 A, C, D) behind chaetiger 24 – 45. Individuals producing stolons found from April to December (Gidholm 1967). Morphology of epitokous stages. Male. Length in preserved specimens 2.8 – 3.6 mm for 3 + (18 – 25) + 0 chaetigers (n = 5), width in region a 0.3 mm, width in region b 0.5 – 0.6 mm. Live specimens faintly greenish with a white middorsal line from intestinal granular accumulations as in stock, without colour markings. Ciliation as in stock. Prostomium with small anterior incision. Nuchal epaulettes rounded, extending to beginning of chaetiger 1. Median antenna reaching middle of region b, chaetiger 10 – 15. Lateral bifid antenna, 2 – 3 times as long as prostomial width; basal part 1 / 2 of total length, rami of about equal size. Frontal processes, equal to 1 / 4 – 1 / 3 of prostomial width. Tentacular cirri 1 pair, 2 / 3 or as long as prostomial width. First dorsal cirri, equal in length to median antenna. Achaetous knobs absent. Cirri on chaetiger 1 equals body width, cirri on chaetiger 2 and 3 shorter, equal to 3 / 4 of body width; cirri in region b shorter than in a, reciprocally equal, measuring c. 1 / 4 of body width. Median ceratophore, small tentacular cirrophores, large cirrophores on first dorsal cirri, short cirrophores in region a, present; cirrophores otherwise absent. Cirri in region a and b fusiform, frontal processes club shaped, other appendages cylindrical. Single neuropodial acicula in all chaetigers; 2 anterodorsal, and 2 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 c. 20 swimming chaetae. Anal cirri equal in length to 2 – 3 times body width. Female. No mature females examined. According to Gidholm (1967) c. 3 mm for 2 + (15 – 18) chaetigers. Tentacular cirri 2 pairs, one egg sac. Habitat. Mostly intertidal, amongst algae, hydroids, and bryozans. Observed to feed on Laomedea geniculata, L. flabbelata, and L. longissima (Okada 1929 c; Gidholm 1967).
description
Description. Length in preserved specimens 5.2 – 9 mm for 42 – 80 chaetigers, width 0.35 – 0,45 mm. Live specimens weekly pink anteriorly, proventricle pinkish, intestinal region yellowish (Fig. 61 A, B); eyes red. Ciliation as 1 troch per segment. Eyes confluent (Fig. 61 A); eye spots present. Palps in dorsal view projecting 1 / 3 – 1 / 2 of prostomial length (Fig. 61 A), fused. Extension of nuchal epaulettes to between end of chaetiger 3 and end of chaetiger 4 (beginning of chaetiger 5 in holotype). Median antenna reaching chaetiger 9 – 13 (n = 4) in preserved specimens. Lateral antennae and dorsal tentacular cirri, length 1 / 2 of median antenna. Ventral tentacular cirri 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 4 DDUUgroups, and 7 – 15 DDUgroups (n = 8). Dorsal cirri from chaetiger 3 alternate in length; short cirri equals 2 / 3 – 3 / 4 of body width, long cirri equal to or slightly longer than body width. Cirrophores present on tentacular cirri, and all dorsal cirri. Cirrophores unequal, cirrostyles equal (Fig. 61 A); cirrophores on short cirri 1 / 2 in length of cirrophores on long cirri (Fig. 61 A); cirrophores on short cirri equal to parapodial lobes, cirrophores on long cirri longer than parapodial lobes; cirrophores on short cirri equal in length to cirrostyles, cirrophores on long cirri longer than cirrostyles (Fig. 61 A). All appendages cylindrical. Parapodial lobes rounded, of medium – large size. Anterior chaetigers with 2 – 3 aciculae, 1 in median and posterior. Chaetal fascicle with 10 – 13 compounds in anterior chaetigers, 4 – 9 in median and posterior. Compound chaetae with small distal tooth; serration present. Single thin bayonet chaetae, beginning between chaetiger 40 – 70. Pharynx with 1 long sinuation anterior and lateral to anterior half of proventricle (Fig. 61 A). Trepan in chaetiger 3 – 7, with 2 large teeth and 25 – 38 smaller; large teeth laterally positioned with 9 – 11 dorsal teeth, and 16 – 19 ventral (n = 8); dorsal teeth smaller than ventral; large teeth mostly fused with adjacent teeth; teeth arranged in 1 ring (Fig. 61 C). Basal ring present; infradental spines present. Proventricle equal in length to 4 – 5.5 segments (Fig. 61 A, B) in chaetiger 12 – 18 with 33 – 42 rows of muscle cells (n = 12). Anal cirri equal in length to 1 – 1.5 times body width. Reproduction. Probably with schizogamy, 2 individuals were found with pink eggs from about chaetiger 29 – 55; one of these had a regenerating posterior end behind chaetiger 55 (Fig. 61 B). Habitat. Subtidal, amongst hydroids, bryozans, and tunicates.
description
Male. Body divided into 3 regions, anterior with 2 – 4 (usually 3) uniramous chaetigers (region a), median with 14 – 24 biramous chaetigers (region b), and posterior with 0 – 8 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 stock, 1 or 2 trochs per segment. 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 absent. Nuchal epaulettes extending maximally to anterior part of chaetiger 1. Large median antenna inserted on posterior part of prostomium, lateral antennae inserted on anterior margin. Lateral antennae bifid, basal part 1 / 6 – 1 / 2 of total length; outer ventral rami equal to or up to 5 times 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. Pair of small processes may be present ventral to lateral antennae, proximal to ventral pair of eyes. Tentacular cirri 1 or 2 pairs. First dorsal cirri (corresponding to " tentacular cirri " (e. g. Gidholm 1967) or " lateral horns " (Hamond 1974) in earlier literature, equal in shape and size to median antenna; achaetous knobs absent. Second dorsal cirri situated above first chaetigerous lobes (referred to as cirri on chaetiger 1 to avoid confusion). 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, small cirrophores absent or present on tentacular cirri, mostly too small to be adequately assessed, cirrophores absent or present on dorsal cirri. Appendages may be cylindrical, fusiform, thick, slightly flattened, flattened, or club shaped. Parapodia in region a and c as in stock but generally smaller; in region b large, flattened and equipped with welldeveloped notopodia. Single neuropodial acicula; notopodia in region b supported by 2 anterodorsal aciculae, and 2 – 3 thick and 3 thin posteroventral aciculae. Neuropodial chaetae as in stock. Notopodial lobes with 15 – 30 swimming chaetae, in length equal to c. body width in region b including parapodial lobes. Pygidium with 2 cirri (reported length compared to body width in region a, excluding parapodial lobes, if not otherwise stated). Female. Body divided into 3 regions, anterior with 2 – 6 uniramous chaetigers (region a), median with 14 – 23 biramous chaetigers (region b), and posterior with 2 – 15 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 stock, 1 or 2 trochs per segment. Prostomium rounded rectangular, wider than long, anterior margin straight or concave. Eyes large, 2 pairs, with lenses; eyes situated on dorsal and ventral side of prostomium, ventral pair larger. Palps absent. Nuchal epaulettes maximally extending to anterior part of chaetiger 1. Median antenna inserted medially on prostomium, lateral antennae inserted on anterior margin. Tentacular cirri 1 or 2 pairs. First dorsal cirri situated above first chaetigerous lobes; achaetous knobs absent. Cirri length measured as body width excluding parapodial lobes in region a, and c; as body width including parapodial lobes in region b. Small cirrophores absent or present on tentacular cirri, mostly too small to be adequately assessed, cirrophores absent or present on dorsal cirri. Appendages may be cylindrical, fusiform, thick, slightly flattened, flattened, or club shaped. Parapodia in region a and c as in stock but generally smaller; in region b with notopodia, not as developed as in male. Single neuropodial acicula; notopodia in region b supported by 2 anterodorsal aciculae, and 2 thick and 2 – 3 thin posteroventral aciculae. Neuropodial chaetae as in stock. Notopodial lobes with 15 – 20 swimming chaetae, in length equal to c. 1.5 times body width in region b, including parapodial lobes. Pygidium with 2 cirri (reported length compared to body width in region a, excluding parapodial lobes, if not otherwise stated).
diagnosis
Diagnosis. Myrianida with c. 18 equal teeth, equal cirri with equal cirrostyles and cirrophores.
diagnosis
Diagnosis. Myrianida with characteristic trepan shared only with M. rangiroaensis (HartmannSchröder, 1992); 2 large teeth laterally positioned with 9 – 11 dorsal teeth, and 16 – 19 ventral teeth; dorsal teeth smaller than ventral; large teeth fused with adjacent teeth; unequal cirri with unequal cirrophores and equal cirrostyles.
diagnosis
Diagnosis. Myrianida with characteristic trepan with 22 – 29 unequal teeth, 1 large alternating with 1 – 3 smaller; thick basal ring; long alternating dorsal cirri with unequal cirrophores and cirrostyles.
diagnosis
Diagnosis. Myrianida with extension of nuchal epaulettes to end of chaetiger 3; 16 – 18 equal teeth in trepan, thin distinct basal ring; short equal cirrophores and alternating cirrostyles.
diagnosis
Diagnosis. Myrianida with long equal cirrophores, and alternating cirrostyles; trepan with 26 – 30 equal teeth, and a thin basal ring.
diagnosis
Diagnosis. Myrianida with much convoluted pharynx; trepan with 9 or 15 – 16 equal triangular teeth, and a thin basal ring.
diagnosis
Diagnosis. Myrianida with reddish orange sides in pharyngeal region; trepan with 24 – 34 equal teeth, basal ring welldeveloped.
diagnosis
Diagnosis. Myrianida with short equal cirri, with equal cirrophores and equal cirrostyles; trepan with 20 – 25 equal teeth.
discussion
Remarks. Myrianida arborea is poorly known, it is similar if not identical to M. brevipes described from Salvador. Myrianida arborea is also very similar to M. edwarsi (Saint Joseph, 1887) but differs in that it lacks the orange colour along the sides in the pharyngeal region found in M. edwarsi; the trepan has generally more teeth in M. edwarsi (24 – 34), compared to c. 18 but variation is not adequately known in M. arborea.
discussion
Remarks. Myrianida australiensis was originally described as a subspecies of Autolytus prolifer, and was later redescribed as A. devaneyi by the same author. The reason for this was probably due to that Myrianida australiensis wrongly was interpreted as having 10 teeth, and nuchal epaulettes reaching end of chaetiger 1. Myrianida australiensis is most similar to M. brevicirrata (Winternitz, 1936) with which it shares the thin basal ring, and combination of equal cirrophores and unequal cirrostyles. However M. australiensis has longer nuchal epaulettes reaching end of chaetiger 3 compared with end of chaetiger 1 in M. brevicirrata, and has only 16 – 18 teeth compared with 26 – 30 in M. brevicirrata; in addition M. australiensis has shorter cirrophores than M. brevicirrata.
discussion
Remarks. Myrianida brachycephala differs from other similar species in the denticulation of the trepan. Other diagnostic characters are the length of the cirrophores relative to the cirrostyles; cirrophores on long cirri are shorter than corresponding cirrostyles, contrasting with M. langerhansi (Gidholm, 1967) whose long cirri have longer cirrophores than cirrostyles. Hamond (1969 a) and Schiedges (1979 a, 1979 b, 1980) discussed the possibility that Myrianida brachycephala, M. prolifera, and M. edwarsi hybridize in Norfolk waters, east of Great Britain, and in Oosterschelde estuary on the coast of the Netherlands. No indication of this has been noted, from molecular or morphological data in the sampled areas, but specimens from Norfolk and Oosterschelde have not been sampled and the matter needs further investigation. At present the species are regarded as different lineages. The suggested synonymies of Proceraea luxurians, and A. mirabilis are based on examination of the type material, whereas the synonymy of Autolytus punctatus and Autolytus benazzi are based on the descriptions, for the latter this is concluded mainly from the figure. In his description Cognetti states that there are 24 equal teeth, but in the figure the teeth are of different sizes; otherwise the description fits well with M. brachycephala. The fact that M. brachycephala is common in the Mediterranean, and that Cognetti did not record it, reinforces the synonymy. SaintJoseph's description of Autolytus ehbiensis refers to M. prolifera at least what regards the trepan structure, but several of the syntypes marked with A. ehbiensis are in fact M. brachycephala. Fauvel's (1923) description seems to be based on a mixture of specimens of A. langerhansi and A. brachycephalus.
Name
- Homonyms
- Myrianida Milne Edwards 1845