Auletta krautteri Austin, Ott, Reiswig, Romagosa & McDaniel 2013

Macroscopic features. Erect, stalked tubes typically single (Fig. 1A), occasionally branched (2 to 3 tubes on a common base); branched forms uncommon. Overall height 5–13 cm, width of tubes 0.7–2 cm. Stalk comprises up to one third of overall height. A single 2–8 mm diameter osculum at the tube apex leads into an atrial cavity extending the length of the tube and into the stalk where the tube diameter is restricted. Wall thickness of the tube 5–10 mm. Surface felt-like to touch. Smooth inner wall penetrated by a series of elongate openings. Consistency compressible but firm and tough. Colour in life reddish-brown; grey or cream in alcohol. Specimens collected in 1965 contained oocytes 130 to 150 µm diameter. Microscopic features. Skeletal architecture simple, composed of one to three multi-spicule tracts oriented parallel to and lining the atrial cavity, which is relatively smooth as a result (Fig. 1B). Single, or multispicular tracts branch from this longitudinal tract approximately at right angles and project to the outer surface. The branches also form short brushes, and where each branch penetrates the surface, the terminal brush forms a tuft to produce a hispid appearance (Fig. 1C). Each tract varies from 150–400 µm in diameter. Ascending tracts are composed primarily of straight and curved styles, and secondarily of sinuous oxeas, curved oxeas and occasional sinuous strongyles (Fig. 1O, P). Straight styles or styles curved near the base form the exterior tips of ascending fibres and curved, bent or sinuous oxeas and styles form cross tract links. The multi-spicule tracts of the atrial cavity are 500–700 µm diameter and composed of bundles of 10 to 15 spicules cemented by spongin Ascending tracts composed of fewer, typically 5 or 6, spicules in a bundle cemented by spongin. Atrial tracts composed primarily of sinuous oxeas, secondarily of curved and straight styles; occasionally sinuous strongyles, sinuous styles, and curved oxeas located in axial tracts. Ectosome surface forms a reticulation in the areas with pores where it is elevated about 2 mm above the general surface. Easily detachable aspicular membranes are present on dermal surface stretched between spicule tracts, and on atrial surface below the longitudinal spicule tracts (Fig. 1B, C). The choanosome occupies the space between the detachable membranes and is distinguished by radial orientation of the spicule tracts, and by the somewhat different proportion of spicules, which is quite variable among different specimens. Oscula may be ringed by long, straight styles singly or in tufts. Fringe may be absent, but if present, extends 100–300 µm beyond the osculum. Stalk is denser than the tube, not hollow except near the tube base, and packed with branching and anastomosing multi-spicule tracts, forming a dense reticulation of two to ten or more spicules to a bundle cemented by spongin. Stalk tracts 100–400 µm diameter. Primary spicules sinuous strongyles which serve to reinforce the stem. The proportion of other stalk spicules is quite variable with sinuous oxeas, bent and curved and straight styles being variably the next most abundant. Sinuous styles and curved or bent oxeas are uncommon. Spicules. Spicule types include straight (Fig. 1F) and bent (Fig. 1H) styles of the multi-spicule tracts; long, straight styles of the oscular fringe (Fig. 1E) and proximate area; sinuous (Fig. 1K, L), curved or bent (Fig. 1M) oxeas, and sinuous strongyles (Fig. 1O, P). Occasionally sinuous oxeas occur that are rounded on one end forming sinuous styles. These latter were enumerated separately to give a qualitative idea of their abundance. Longer styles often have a reduced diameter at the head comparable to mycalostyles. Oxeas are often anisometric. Both oxeas and styles occasionally have mucronate or rounded apices. Oxeas and strongyles may occasionally be centrotylote. Five specimens were examined in detail (Table 1). Comparison of spicules in Auletta krautteri specimens examined in detail. ID Location Latitude, Longitude Depth (m) Length (µm) Straight Style Curved Style Sinuous Oxea Curved oxeas Sinuous Strongyle Oscular Styles KML1105 Hecate Strait, BC 52°26.4'N, 129°40.0'W 215 270–1350 240–880 440–1300 330–1070 420–1595 none Spicule Abundance Many straight and curved styles, and sinuous oxeas throughout. Strongyles abundant in stem, rare in atriosome, uncommon in ectosome. Curved oxeas uncommon in stem. Bent and curved oxeas uncommon to moderately common. KML1106 Dixon Entrance, BC 54°37.0'N, 133°55.0'W 229 320–1280 220–990 380–1274 220–880 250–1430 none Spicule Abundance Styles and sinuous oxeas abundant in ectosome and atriosome, uncommon to moderately common in stem. Strongyles abundant in stem, uncommon in ectosome and rare in atriosome. Bent and curved oxeas uncommon to rare. KML1108 Goose Bank, QC Sound BC 51°30.0'N, 128°0.0'W 92 111–1300 119–940 310–1100 250–880 300–1150 970–2375 Spicule Abundance Straight styles abundant in ectosome, common in atriosome, uncommon in stem; bent styles abundant throughout. Sinuous oxeas common throughout. Strongyles abundant in stem, uncommon in atriosome, rare in ectosome. Bent and curved oxeas moderately common except rare in stem. KML1109 Dixon Entrance, BC 54°30.2'N, 133°53.3'W 256 250–1500 230–720 105–1250 123–920 440–1120 680–2450 Spicule Abundance Styles and sinuous oxeas abundant throughout. Sinuous strongyles abundant in stem, uncommon elsewhere. Bent and curved oxeas rare in stem, common elsewhere. KML1107 W of Flamingo Inlet, BC 52°89.8'N, 131°23.8'W 200 325–926 220–790 325–1005 276–768 286–1281 926–1050 Spicule Abundance Styles and sinuous oxeas abundant in the ectosome and atriosome; uncommon to rare in the stem. Strongyles abundant in the stem, rare in atriosome, uncommon in the ectosome. Bent & curved oxeas rare in stem, uncommon elsewhere.