Aaptos aaptos (Schmidt, 1864)
N.B. The name Aaptos aaptos is used for congeneric specimens from all overthe world; synonymy given here is restricted to Europe.
Ancorina aaptos Schmidt, 1864: 33, pl. IV fig. 11; Schmidt, 1868: 17
Aaptos adriatica Gray, 1867: 519
Aaptos aaptos; Schmidt, 1870: 268; Topsent, 1925a: 631; Lévi and Vacelet,
1958; Rodriguez and Gondar, 1978: 37; Acua et al., 1984; Solórzano, 1991:22; Desqueyroux-Faúndez and Stone, 1992: 7, 94; Hooper andWiedenmayer, 1994: 346; Kelly-Borges and Bergquist, 1994: 304, figs. 2a-b,pl. Ia.
?Trachya pernucleata Carter, 1870: 176
Tuberella tethyoides Keller, 1880: 277, pl. 14 figs. 7-9; Vosmaer, 1886: 327,pl. XXVI fig. 9; Topsent, 1896: 125.
Tethyophaena silifica Schmidt, 1880: 281.
Suberites spissus Topsent, 1892b: xxvii.
Suberites aaptos; Von Lendenfeld, 1896: 140, pl. VII, XII.
Tuberella aaptos; Topsent, 1898b: 127; 1900: 285, pl. VIII figs. 12-13.
Species Overview
Aaptos aaptos (Schmidt, 1864) is a greyish yellow or reddish dark brown,
massively lobate, hard, sponge. Surface irregular, but without distinct
papillae. Its main distribution is in Mediterranean waters, but it is reported
also rarely from NW Spain.

Taxonomic description
Colour: Brown-yellow, occasionally pale yellow or greyish, or reddish darkbrown. Interior yellow.
Shape, size, surface and consistency: Massive, lumpy, bluntly lobate,typically 3-5 cm in diameter, occasionally larger, fist-size. Surface irregular,
hispid, occasionally smooth, seldom elevated in distinct papillae. Oscules up
to 3 mm in diameter, few in number, contractile, occasionally elevated.
Consistency compact, firm, hard.
Spicules: Strongyloxeas and styles. The strongyloxeas are characteristicallythickest in the middle, thinning out towards the blunt apex: 750-1050 x 1245 µm (possibly divisible into two size categories). Ectosomal small styles,
occasionally subtylostyles: 150-700 x 1-8 µm, likewise divisible in two size
categories.

Skeleton: Radiate architecture with spicule tracts of 1.5-2 cm length, 10-20
spicules in thickness, radiating from a focal point towards the surface. At thesurface these bundles are strengthened and linked by a palisade of small
styles, making a continuous ectosomal cortex of about 1 mm in thickness,
which is however not macroscopically distinct and not fibrous. Inhalant canals
traverse the cortex in a sinuous way. Below the cortex the choanosomal
tracts are separated by subectosomal cavities.

Cell biology: The choanosome is rich in spherulous cells. The choanocyte
chambers are small, eurypylous, 20-25 µm in diameter.
Ecology: Mostly known from deeper water, but occasionally occurring in theshallow sublittoral.
Distribution: A southern species occurring off the coasts of NW Spain andPortugal; elsewhere in the Mediterranean, Azores, Madeira and CanaryIslands.
Etymology: Aaptos (Greek) = invincible or strong, referring to theconsistency.
Type specimen information: Syntype in the Graz Museum, LMJG 15705,Lagosta, Adriatic; dry fragment in the Natural History Museum, London,BMNH 1854.12.21.18 (as Ancorina); also slides in BMNH and ZMB (Mus.
Berlin).
Remarks
This species is not well-known. It has been reported from many areas of theworld, but it is almost certain that these concern other species of Aaptos. A
second, sympatric species of Aaptos is A. papillata (Keller, 1880), equally illknown, but distinguishable from the present species by the surface papillae,
reddish colour and the possession of small tylostyles. A possible third species
is "Trachya" pernucleata Carter (1870), here considered a junior synonym ofA. aaptos, but Kelly-Borges and Bergquist (1994) maintain it is a separate
species of Aaptos.
The BMNH type fragment has been redescribed by Kelly-Borges andBergquist (1994).
Sources: Topsent, 1900; Kelly-Borges and Bergquist (1994).