Ceratopera pacifica, (KARLING, 1986), 2018

CERATOPERA PACIFICA ( KARLING, 1986) View in CoL COMB. NOV.

( FIG. 5A, C, D)

Messoplana pacifica Karling, 1986: 210 –211 View in CoL , figs 41–44, 49.

New localities: Dixon Island , Bamfield, British Columbia, Canada (48°51 ′ 05 ″ N, 125°07 ′ 19 ″ W), algae in rocky lower intertidal (02/06/2015) GoogleMaps . Little Wolf Beach , Calvert Island, British Columbia, Canada (51°39 ′ 53 ″ N, 128°07 ′ 44 ″ W), algae in rocky lower intertidal (07/04/2016) GoogleMaps . West Beach boulders, Calvert Island, British Columbia, Canada (51°39 ′ 07 ″ N, 128°08 ′ 33 ″ W), algae in rocky lower intertidal (09/04/2016) GoogleMaps .

Known distribution: Northeast Pacific Ocean: California ( Karling, 1986).

Material: Observations on three live animals. One whole mount ( BBM MI4049 ). 18S rRNA (GenBank accession # MF321748 View Materials ), 28S rRNA (GenBank accession # MF321758 View Materials ) .

Diagnosis: Species of Ceratopera with partly coiled stylet. Stylet composed of a 120- to 184- μ m-long, filiform stylet proper with a cup-shaped proximal part, and a 58- to 64- μm-long, funnel-shaped accessory mantle piece. Cup of the stylet proper connected to the mantle piece by a sclerotic string; filiform part partially enclosed by the mantle piece. Bursa with bursal canal. Bursal appendage 20 μ m long and consisting of a proximal tube that protrudes into the bursa and distally splits in two smaller tubes.

Remarks: Animals about 1.3 mm long, fusiform, with some specimens displaying a parenchymatous brownish coloration ( Fig. 5A). General appearance, internal organization and the morphology of the stylet and bursal appendage correspond with those of ‘ Messoplana pacifica ’ (see Karling, 1986). The stylet proper and the accessory mantle piece of the mounted specimen measure 184 μ m (non-axial: 82 μ m) and 58 μ m (non-axial: 56 μ m), respectively ( Fig. 5D). Although the stylet is a bit larger, this is still in line with the measurements for the Californian specimens (120–170 μ m and 58–64 μ m, respectively). Bursa, bursal canal and small bursal appendage are faintly visible in the live animal ( Fig. 5C).

Karling (1986) attributes his specimens to the genus Messoplana . Although he does not explicitly mention why, he lists some of the features also found in other representatives of this genus such as the mid-body position of the pharynx, a sclerotic string that connects the stylet proper and its accessory piece, a small, bitubular bursal appendage (‘insemination apparatus’) and a bursa with a bursal canal. Based on the ambiguity of the morphological characters differentiating Messoplana from Ceratopera sensu Den Hartog and the results of our phylogenetic analysis, all species of Messoplana are transferred to Ceratopera . See the discussion on C. complicata sp. nov.