Subfamily
Autolytinae
Autolytinae is a subfamily with 8 genera and approximately 117 species.
DIAGNOSIS
Autolytus (Proceraea) picta has a very large body, exceeding Eusyllis assimilis with up to 25 mm in length (100 segments), and has a very characteristic coloration in brown bands that run from the first segment under the prostomium to the middle of the body. (Fig. 1A). It has a rounded prostomium and four large eyes, also arranged in a trapezoid. Its palps are fused and reduced, and are hidden under the prostomium, so they are not usually noticeable. It is also differentiated by its long appendages in the area of ​​the head: it has 3 long, thick and twisted antennae, and the anterior cirri are very long, although their length progressively decreases towards the back. Its proventricle is thick, attached to a long pharynx frequently twisted on itself. It presents aciculae with a curved tip (Fig. 1B). As for its chaetae, it has two morphologies: compound, with a proximal tooth longer than the distal and short spines, and simple bayonet chaetae (Figs. 1C, 1D, 1E).
Figure 1. Autolytus picta: A) Anterior dorsal view; B) Aciculae; C) Medium compund chaetae; D) Bayonet chaetae; E) Posterior compound chaetae. Scales: A, 0.195 mm; B–E, 20 µm. Original work
VARIABILITY
Bodies of variable thickness, with uniform coloration, sometimes with spots, also warty. Their palps are often reduced, and their appendages may be smooth, short, and thick, larger and more prominent in the anterior part of the body, or long and partially segmented, or absent. The setae vary enormously: there can be bidentate, in bayonet or, in those species with only simple bidentate, thickened, spine-crowned, or low-cut tip chaetae, or even having all the morphologies of the chaetae in a single setiger (Figs. 2A, 2B). The handles of the compound chaetae also present variability, some ending in a crown of thorns (Figs. 2C, 2D). The aciculae usually have a rounded or curved tip. To access more figures on these morphologies, review other subfamilies.
Figure 2. Detail of the variabilities of the Autolytinae family: A) Compound bayonet chaetae; B) Modified compund chaetae; C) Simple bidentate chaetae with a basal spur; D) Simple bidentate chaetae with a thickened edge ending in thorns. (1)
Autolytinae colour image © Greg Rouse, Scrips Institution of Oceanography, 2003.
(1) San Martín, G. (2003). Museo Nacional de Ciencias Naturales, CSIC, 21.