Mychophilus notialis, Kim & Boxshall, 2021

Kim, Il-Hoi & Boxshall, Geoff A., 2021, Copepods (Cyclopoida) associated with ascidian hosts: Ascidicolidae, Buproridae, Botryllophilidae, and Enteropsidae, with descriptions of 84 new species, Zootaxa 1, pp. 1-286 : 279-281

Mychophilus notialis sp. nov.

( Fig. 184 )

Type material. Holotype ♀ (MNHN-IU-2014-21589) and paratype ♀ (dissected, MNHN-IU-2014-21498) from Bçtryllçẚdes magnẚcçecum (Hartmeyer, 1912); Kommetjie, Cape Town, South Africa, intertidal, Monniot coll., 05 February 1996.

Etymology. The name nçtẚalẚs is from the Latin, meaning “southern”, alluding to the location of the type locality in the South Africa.

Description of female. Body ( Fig. 184A ) vermiform, cylindrical, unsegmented, recurved dorsally, consisting of cephalosome and trunk. Body length 1.63 mm; maximum width 273 μm. Cephalosome defined from trunk by posterodorsal wrinkles. Genitoabdominal region longer than metasomal region; genital apertures positioned laterally at midlength of trunk. Anus located dorsally, positioned at level of insertion of leg 3. Caudal ramus ( Fig. 184C ) small, incompletely articulated from trunk, gradually narrowing distally, about 2.1 times longer than wide (40×19 μm), armed with 1 broad seta (12 μm long) at apex.

Rostrum ( Fig. 184B ) as broad ridge connecting left and right antennules. Antennule ( Fig. 184D ) small, 35μm long, 2-segmented; proximal segment unarmed; distal segment shorter and narrower than proximal segment, armed with 5 setae. Antenna ( Fig. 184E ) 73 μm long, 2-segmented, tapering, unarmed; proximal segment with 2 rows of spinules on lateral surface; distal segment claw-like, with pointed apex and several rows of spinules.

Labrum broad, with transverse row of 6 transparent, broad, tongue-like elements on ventral surface; elements subequal in length, marginally spinulose distally. Mandible absent. Maxillule ( Fig. 184G ) bilobed; larger inner lobe bearing 2 spinulose processes; smaller outer lobe bearing 3 spinulose processes (1 arising more proximally). Maxilla ( Fig. 184H ) 2-segmented; proximal segment unarmed; distal segment small, knob-like, tipped with 1 broad seta. Maxilliped absent.

Leg 1 ( Fig. 184I ) consisting of 2-segmented, unarmed protopod and rudimentary exopod and endopod. Proximal segment of protopod ornamented with several rows of spinules on anterior surface; distal segment with 2 or 3 rows of spinules on anterior surface. Exopod and endopod not articulated from protopod. Exopod sclerotized, clawlike, embedded in hyaline covering. Endopod fleshy, bearing 1 spiniform process on anterolateral surface. Legs 2, 3, and 4 ( Fig. 184J ) as leg 1 in form, but broader; exopod and endopod indistinctly articulated from distal segment of protopod. Legs 5 and 6 absent.

Male. Unknown.

Remarks. In Mychçphẚlus the labrum and maxillule exhibit useful taxonomic characters. The labrum of M. nçtẚalẚs sp. nov. bears 6 setiform processes. Only M. palmatus is known to have this number of processes on the labrum ( López-González & Conradi, 1996). Both species also have a maxillule bearing 2 processes on the inner lobe and 3 processes on the outer lobe. However M. nçtẚalẚs sp. nov. is easily distinguishable from M. palmatus, by having a 2-segmented antennule (cf. unsegmented in M. palmatus) and a 2-segmented antenna (cf. unsegmented in M. palmatus). The labrum is unknown in M. fallax, but this species is not confusable with M. nçtẚalẚs sp. nov. as it has a slender body, an antennule bearing 2 spinules distally, an antenna bearing a slender terminal claw, and a maxillule (referred to as the “mandible” by Stock, 1967) with a simple inner lobe.

The maxillule of M. nçtẚalẚs sp. nov. is armed with 2 processes on the inner lobe and 3 processes on the outer lobe as in M. palmatus and M. rçseus. The type species, MK rçseus has bipartite caudal rami, 3 processes on the labrum, and 3-segmented antenna ( Ooishi, 2008c), and is therefore easy to distinguish from M. nçtẚalẚs sp. nov .

Figures

FIG. 184. Mychçphẚlus nçtẚalẚs sp. nov., female. A, habitus, left; B, cephalic appendages ẚn sẚtu, ventral; C, caudal ramus; D, antennule; E, antenna; F, labrum; G, maxillule; H, maxilla; I, leg 1; J, leg 4. Scale bars: A, 0.1 mm; B, I, J, 0.02 mm; C-H, 0.01 mm.