Autolytus simplex Ehlers, 1900

Autolytus simplex Ehlers, 1900: 213; Ehlers 1901: 97 –98, pl. 10, fig. 5–8.

NOT Autolytus simplex Augener 1922, 190–191; Monro 1930: 97 –98; 1936: 132–133; 1939: 114; Hartman 1953: 27; 1964: 78–79; Wesenberg­Lund 1961: 66. = Proceraea sp, or Procerini sp.

Material examined. Chile: Non­type material, 1 spm, ZMH V­ 9258, Masatierra, calcareous algae, 30–45 m, 1 Apr 1917, det. Augener.

Description. Type material lost. Description based on Ehlers' description. Length 6 mm for 54 chaetigers, width 0.5 mm including parapodial lobes; length of stock 4.5 mm for 41 chaetigers, length of stolon 1.5 mm for 12 chaetigers. Preserved material without colour markings; eyes red­brown.

Prostomium wider than long with four eyes, with lenses, in trapezoid arrangement. Eyes separated (Ehlers 1901: fig. 5); eye spots not mentioned. Palps of unknown size. Nuchal epaulettes not mentioned.

Three long antennae, median longer. Tentacular cirri 2 pairs, longer than body width, dorsal pair longer. First dorsal cirri longer than antennae. Alternation in direction not assessed. Dorsal cirri unequal; short cirri shorter than 1/2 body width, long cirri longer than 1/2 body width. Cirrophores present on tentacular cirri, and all dorsal cirri. Cirrophores seem to be unequal (Ehlers 1901: fig. 6); uncertain if cirrostyles are equal or unequal. Cirrophores shorter than cirrostyles. All appendages cylindrical.

Parapodial lobes conical, large (in length 1/4 of body width). Unknown number of aciculae. Chaetal fascicle with c. 10 compounds. Compound chaetae with small distal tooth (Ehlers 1901: fig. 6); absence/presence of serration not known. Bayonet chaetae not described.

Pharynx with sinuation anterior to proventricle. Trepan in chaetiger 3, described as unarmed. Proventricle equal in length to 5.5 segments in chaetiger 8–13 with 42 rows of muscle cells.

Reproduction. Schizogamy behind chaetiger 41. The stolon is possibly not fully developed, as there is no description of swimming chaetae.

Distribution. Strait of Magellan.

Remarks. It is uncertain if Ehlers' species is possible to identify from his description. Later authors, starting with Augener, have referred specimens, both atokes and stolons, of one or possibly several Proceraea ­species, to A. simplex . The length and shape of cirri, and cirrophores together with its reproductive mode indicates that A. simplex belongs to Myrianida . Ehlers' description of an unarmed trepan is not reliable as the structure is difficult to see, and many earlier descriptions are erroneous. Considering cirri­characters, length of proventricle (with consideration taken to that Ehlers' specimen may be contracted), and number of rows of muscle cells, there are many taxa that are similar to A. simplex, including A. afer, M. brachycephala, M. dentalia, M. prolifera, M. langerhansi, M. longoprimicirratus, M. multidenticulata, and M. rangiroaensis . As A. simplex is currently insufficiently known, it is considered as Myrianida incertae sedis .