Autolytus maclearanus McIntosh 1885

Autolytus maclearanus McIntosh, 1885 (Fig. 92A–E)

Autolytus maclearanus McIntosh, 1885: 207 –208, pl. 29, fig. 6, pl. 33, fig. 5, pl. 15A, fig. 15.

? Autolytus maclearanus Ehlers 1912: 19; 1913: 488–493, pl. 33, fig. 9–11; Benham 1927: 60; Knox 1960, 109; Day 1960, 318; Hartmann­Schröder & Rosenfeldt 1990: 100.

? Autolytus (Polybostrichus) maclearanus Wesenberg­Lund 1961: 68, fig. 21.

Not Autolytus maclearanus Day 1967: 284, figs 12.13A–E (= Procerini).

Autolytus gibber Ehlers, 1897: 55 –57, pl. 3, fig. 71–72.

? Autolytus gibber Gravier 1906: 283; Monro 1930: 97; 1936: 133–134, fig. 23; Fauvel 1936b: 21; 1950: 758; Hartman 1953: 27; 1964: 77–78, pl. 24, fig. 2.

? Autolytus (Polybostrichus) gibber Wesenberg­Lund 1961: 66 –67.

Not Autolytus gibber Hartmann­Schröder 1965b: 129 –131, figs 96–98 (=near Epigamia charcoti).

Material examined. Antarctic Sea: holotype BMNH 1885.12.1.156, Kerguelen Island, off Cape Maclean, Challenger expedition, stn. 149E, 49°37'S, 70°16'E, 21 Jan 1874; Chile: holotype of A. gibber, ZMH V­ 1211, Süd­Feuerland, Beagle Channel, Lapataia Nueva, Meeresstrand, 4 Dec 1892.

Description. Holotype of A. maclearanus in two fragments, complete; length 13 mm for 66 chaetigers, width 0.9 mm. Holotype of A. gibber, one anterior fragment, length 4.3 mm for 12 chaetigers, width 0.7 mm. Preserved material yellowish with brown bacillary glands in transverse intrasegmental bands on dorsum, in 2 rows on each dorsal cirri (Fig. 92B), and in a more or less distinct spot at the base of the dorsal cirri; bacillary glands not observed in holotype of A. gibber.

Body stout, excluding parapodial lobes cylindrical, venter flattened, body width fairly constant with tapering end. Ciliation not possible to assess.

Eyes separated; eye spots absent. Palps in dorsal view projecting c. 1/4 of prostomial length, fused (Fig. 92A). Extension of nuchal epaulettes to half of chaetiger 1 (Fig. 92A).

Antennae lost or in poor shape, not assessed. Dorsal tentacular cirri reaching chaetiger 3. Ventral tentacular cirri 1/3 as long as dorsal pair. Second dorsal cirri as long as dorsal tentacular cirri. Alternation in direction not evaluated. In anterior part to c. chaetiger 15 (difficult to assess due to lost cirri) cirri alternate in length; short cirri equals c. 1/3 of body width, long cirri equals c. 1/2 of body width; more posterior cirri more or less equal in length, 1/4 of body width. Cirrophores on tentacular cirri and first dorsal cirri present, cirrophores on dorsal cirri may be present, but very small. All appendages cylindrical.

Parapodial lobes very large, with dorsal part enlarged, and distinctly set off from ventral part, especially so in median chaetigers (Fig. 92B). Anterior chaetigers with 3–4 aciculae. Chaetal fascicle with 15–20 compounds in anterior chaetiger, 6–8 in posterior. Compound chaetae with small distal tooth; serration present (Fig. 92E). Bayonet chaetae not found.

Pharynx with sinuation anterior and lateral to anterior part of proventricle (Fig. 92C). Trepan in chaetiger 1–2 (Fig. 92C), not possible to assess details of trepan (Fig. 92D). Proventricle equal in length to 3–5 segments (Fig. 92C) in chaetiger 6–11, with 37–42 rows of square shaped muscle cells. Anal cirri equal in length to dorsal cirri in posterior part.

Reproduction. Unknown, but see remarks.

Habitat. Volcanic mud, 55 m.

Distribution. Antarctic. Kerguelen Island.

Remarks. Autolytus maclearanus most probably belong within Epigamia. It is possibly close to the subgroup comprising E. alexandri, E. alternata, E. charcoti, E. noroi, and E. magna; this can not, however, be safely concluded with available material. Support for this are the presence of many bacillary glands as two bands on each segment, and on ventral and dorsal side of all appendages, found in most of the above mentioned taxa; and the very large parapodia with well­developed dorsal parts. It can not be excluded that the large parapodial lobes, most developed in median chaetigers in McIntosh' specimen, is an epitokous modification. McIntosh also stated that the specimen was distended with sperms. Contrasting with the above mentioned taxa, the chaetae in A. maclearanus has small distal tooth, instead of large. But on the other hand, there are other Epigama ­taxa with small distal tooth, for example E. planipalpa. Several authors, beginning with Ehlers, have assigned epitokous stages of an epigamous species (or several species), to A. maclearanus, and A. gibber. This may be correct, but can at present not be safely confirmed. Ehlers' description of the atokous form of A. maclearanus most probably refers to another species. His specimens do not have any colour markings, and his figures show a specimen with distinctly alternating cirri with distinct cirrophores. Hartmann­Schröder's redescription of A. gibber refer to another Epigamia ­taxon, with large distal tooth, possibly E. charcoti. Many of the records of A. maclearanus and A. gibber are considered questionable at present, because the descriptions can refer to any or several Autolytine species. A. gibber Ehlers, 1897, is considered as a synonym based on examination of type material. Autolytus maclearanus is here referred to as Epigamia incertae sedis.