Pycnaspis, Van, Robert J. & Dekelboum, Allen M., 2011

Van, Robert J. & Dekelboum, Allen M., 2011, Oxynaspididae (Crustacea, Cirripedia): phylogenetics and evolutionary ecology, with descriptions of three new genera and six new species, Zootaxa 3103, pp. 1-32 : 3

Genus Pycnaspis gen. nov.

Figure 2

Type species. Pycnaspis connectens ( Broch, 1931: 34–38).

Type locality. “Kei-Islands: [ Malaysia] St. 49. 5° 37’ S., 132°23’ E., 245 m., sand. May 3rd, 1922. One specimen fixed to a silicious sponge”.

Material examined. Holotype of Oxynaspis connectens Broch, 1931 ; ZMUC 6068, borrowed from the Zoological Museum of the University of Copenhagen, Denmark.

Diagnosis. All 5 plates completely calcified, approximate. Plates more heavily calcified and thicker than those in Oxynaspis and Minyaspis . Scutum with shallow adductor muscle pit; lacking distinct ridge running from umbo to apex. Tergum proximal to scutum and carina, without prominent projections on margins or raised bumps on surface. Carinal surface smooth, basal end rounded, not forked. Attached to silicious sponge, not known to be a symbiont of Antipatharia .

Etymology. From the Greek, pycn -, solid, thick, strong, and aspi -, shield (scutum).

Remarks. As with Archoxynaspis gen. nov., there are no uncalcified areas between the capitular plates. The plates are not thin and fragile, as they are in Oxynaspis and Minyaspis gen. nov., but thick and sturdy; Broch (1931: 34–35) states “On the whole the plates must be characterized as remarkably strong and thick; they are far stronger than in Oxynaspis celata .” Pycnaspis gen. nov. is similar to Archoxynaspis in retaining most of the plesiomorphic features of capitular plates, similar to those exhibited in Lepas , with the exception of the shallow adductor muscle pit on the scutum of Pycnaspis connectens . It is also noteworthy that Broch (1931) found his specimen on a sponge, not an antipatharian. Our examination of the type specimen did reveal a golden-brown chitin sheath covering the entire animal. We take this as further evidence that the chitin coverings commonly seen on all oxynasipidids are at least in part generated by the barnacle and not exclusively by the host antipatharian.

Figures

FIGURE 2. Pycnaspis connectens (Broch, 1931), copy of Figure 13 from Broch, 1931. Specimen in side view (a), first cirrus with basal filamentary appendage (b), mouthparts in side view (c), labrum seen from the ventral side (d), mandible (e), maxilla 1 (f).