Minyaspis opreskoi, 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 : 19-22

Minyaspis opreskoi sp. nov.

Figures 11 , 12

Material examined. Holotype: CASIZ 110163, 1 complete intact specimen, attached to Antipathes cf. A. spinulosa (Schultze) ( CASIZ 113587); Fiji Is, N Astrolabe Reef, outer SW corner; 18° 40.54’ S, 178° 31.34’ E; depth: 17 m; 20 June 1998; coll. Robert Van Syoc (RVS-443). Paratypes (all from same locality as holotype): CASIZ 172660, 1 specimen. CASIZ 110162, 1 specimen, shell plates mounted on SEM stub, mouthparts and cirri on glass microscope slide, peduncle preserved in 75% EtOH. CASIZ 110161, 9 specimens. SIO-BIC C11216, from CASIZ 110161.

Diagnosis. Carina forming nearly 90° angle at umbo, basal end with broad, shallow fork ( Fig. 11 A,B); tergum with large tooth-like projections on occludent margin ( Fig. 11 D,E); scutum possessing sharply produced corners, basal margin deeply incised ( Fig. 11 F,G); filamentary appendages lacking on dorsum and at base of Cirrus 1.

Description. Capitulum with large non-calcified areas between plates; capitular height less than twice its width; low growth ridges on all plates; covered with chitinous, golden-brown epicuticle.

Scutum ( Fig. 11 F,G; Fig. 12 A) irregularly shaped, not quadrangular; umbo subcentral, not on occludent margin; separated from carina by wide non-calcified area except near basal margin of carina; near tergum at single point at apex; occludent and basal margins forming angle about or slightly greater than 90°; basal margin with deep concavity on half closest to occludent edge; entire occludent margin coincident with mantle margin; occludent edge with 1–3 large protuberances; carinal margin broadly concave in upper half; adductor muscle pit shallow; exterior lacking small protuberances.

Tergum ( Fig. 11 D,E; Fig. 12 A) broadly triangular; margins nearly touching carina and scutum only near their respective apexes; umbo not apical; scutal margin smooth; occludent edge irregular, with large tooth-like projections producing pectinate edge; exterior lacking protuberances.

Carina ( Fig. 11 A,B,C; Fig. 12 A) curved in upper portion, line from apex to umbo passing outside of carina, similarl line from apex to basal/peduncular margin not passing through scutum; umbo between lower one-fifth and lower one-third; basal margin truncate, not deeply forked, not extending across peduncle; longer than scutum; width narrowest at umbo; extending up more than one-half length of tergum; with shallow inflection between basal margin and umbo; exterior with small protuberances.

Labrum bullate.

Mandible ( Fig. 12 B) with 5 teeth, first largest, second and third about half length of first, fourth and fifth smaller; face of mandible, superior and inferior margins setose.

First maxilla ( Fig. 12 C) lacking notch, cutting edge very slightly depressed from superior margin until about midpoint of cutting edge where it bulges out, rounding broadly into inferior margin; face of maxilla, superior and inferior margins setose.

Cirrus I ( Fig. 12 D) with anterior ramus shorter than posterior; other cirri with rami of about equal length. Setae simple. Cirral counts are as follows:

CI CII CIII CIV CV CIV Ant. 10 13 19 19 18 20 Post. 13 14 19 19 18 20

Ant. 10 14 18 21 19 18 Post. 13 15 19 19 19 19 Caudal appendages uniarticulate with several spines on dorsal surface close to tips. Filamentary appendages lacking at base of cirrus I. Dorsal filamentary appendages lacking.

Etymology. Named for Dennis Opresko for his work on antipatharian taxonomy and his identifications of the host taxa of the cirriped species described herein.

Remarks. Minyaspis opreskoi sp. nov. lies closest to the branch of M. aurivilli ( Stebbing, 1900) and M. welchi sp. nov. in our phylogenetic tree ( Fig. 15 ). It differs from these two taxa by having the scutum with a smooth occludent margin and external surface, without teeth or protuberences ( Fig. 11 E). The tergum of M. opreskoi is also smooth on the external surface and along the scutal margin ( Fig. 11 C). The tergal umbo on M. opreskoi is not apical ( Fig. 11 C); however, it is apical in M. aurivilli and M. welchi . Similarly, the carinal base of M. opreskoi is not inflected ( Fig. 11 B), whereas it is inflected in M. aurivilli and M. welchi ( Fig. 13 A–C).

Figures

FIGURE 11. Minyaspis opreskoi sp. nov. Paratype CASIZ 110162. Carina, dorsal view (A), oblique view (B), side view (C). Tergum exterior (D), interior (E). Scutum exterior (F), interior (G). Scale bar equals 1.5 mm for A, C, D, E, F and G; 1 mm for B.

FIGURE 12. Minyaspis opreskoi sp. nov. Paratype CASIZ 172660; outline of whole specimen showing general arrangement of plates in relation to each other (A), plate details are not shown in this simple outline drawing, see SEMs in Fig. 11 for plate details. Paratype CASIZ 110162, Mandible (B), Maxilla 1 (C), Cirrus I (D). Holotype CASIZ 110163; whole specimen, attached to branch of host, with host tissue covering capitulum (E).

FIGURE 13. Minyaspis welchi sp. nov. Paratype CASIZ 110149. Carina, dorsal view (A), oblique view (B), side view (C). Tergum exterior (D), interior (E). Scutum exterior (F), interior (G). Scale bar equals 750 µm for A, B, C; 600 µm for D, E, and F; 850 µm for and G.

FIGURE 15. Phylogenetic consensus of 18 shortest trees (147 steps each) using morphological characters for known taxa of Oxynaspididae and two outgroup species, Lepas anatifera and Dosima fascicularis.