Mycetomorpha abyssalis, Kakui, 2024

Kakui, Keiichi, 2024, A new parasitic barnacle (Crustacea, Cirripedia, Rhizocephala, Mycetomorpha) from the abyssal zone in the northwestern Pacific, Zoosystematics and Evolution 100 (2), pp. 385-390 : 385

Mycetomorpha abyssalis sp. nov.

Figs 2 , 3 , 4

Etymology.

The specific name abyssalis (Latin: abyssal) is an adjective referring to the collection of this species from an abyssal depth.

Type host.

Sclerocrangon zenkevitchi Birshtein & Vinogradov, 1953 ( Decapoda : Caridea : Crangonidae ).

Attachment site.

Pleonite 1 sternite.

Type locality.

Off the eastern coast of Iwate, Japan, northwestern Pacific (39°28.555'N, 143°47.347'E to 39°27.934'N, 143°47.240'E), depth 3893-3890 m.

Material examined.

Holotype, female (CBM-ZC 17789), one vial, ex. S. zenkevitchi (cl 26.7 mm; CBM-ZC 17788), collected on 29 September 2023 at the type locality, R/V Hakuho-maru cruise KH-23-5, coll. by Keiichi Kakui.

Representative DNA sequences.

One sequence each was determined from the holotype (CBM-ZC 17789) for COI (INSD accession number LC799150; 637 bp, encoding 212 amino acids), 16S (LC799151; 490 bp), 18S (LC799152; 1826 bp), and 28S (LC799153; 1169 bp). One sequence each was determined from the host (CBM-ZC 17788) for COI (LC799154; 658 bp, encoding 219 amino acids) and 18S (LC799155; 1846 bp).

Description of female holotype.

Externa (Figs 2 , 3 ) 16.6 mm in length, thinner than broad, a little over twice as long as maximum width (8.1 mm), rounded at ends, pale yellow (faded in ethanol, slightly yellowish); except dorsal and anteroventral regions, externa surface covered with short lobes; filled with developing embryos. Root system not observed. Stalk short, cylindrical, at one-quarter of length from posterior end of externa. Triangular shield lacking (Figs 3C , 4 ). Anterior, middle, and ventral lobes short, and ovoid or digitiform; posterior lobes short and branched. Tubular lobe anterior to stalk, at one-fifth of length from anterior end of externa, arising from right margin of externa, with mantle opening at tip; mantle opening anterior to stalk.

Distribution.

Presently known only from the type locality.

Figures

Figure 2. Mycetomorpha abyssalis sp. nov., holotype, attached to the host, Sclerocrangon zenkevitchi Birshtein & Vinogradov, 1953, fresh specimen. Scale bar: 10 mm.

Figure 3. Mycetomorpha abyssalis sp. nov., holotype, fresh specimen. A. Habitus, parasitic on the host, ventral view; B, C. Habitus, ventral (B) and dorsal (C) views; ant - anterior; lef - left; man - mantle opening; rig - right; pos - posterior; sta - stalk; tub - tubular lobe. Scale bars: 10 mm.

Figure 4. Mycetomorpha abyssalis sp. nov., holotype, showing stalk penetrating the host pleonite- 1 sternite (soft tissue in pleonite 1 removed), anterodorsal view; no triangular shield observed. ant - anterior; pos - posterior; sta - stalk. Scale bar: 10 mm.