Armatoglyptes thomasi, Kolbasov & Newman, 2005

Kolbasov, Gregory A. & Newman, William A., 2005, Revision of the Lithoglyptidae sensu Tomlinson, 1969 and Lithoglyptes Aurivillius, 1892 (Cirripedia, Acrothoracica,), including a new species from Bermuda, Zootaxa 1013 (1), pp. 35-64 : 52-54

Armatoglyptes thomasi sp. n.

Figs. 7 , 8

Diagnosis. An Armatoglyptes having an indistinct orificial knob lacking armament but without lateral bars, opercular bars supporting a pair of well­developed recurved posterior projections and a pair of small armed elevations at approximately 1/3 back along the length of the aperture, and a mandible with a comb of sharp spines along the lower half of the cutting edge.

Material: Three females with three dwarf males (one on holotype and two on one of the paratypes). The holotype and a paratype were boiled in KOH for light microscopy investigations. The dissected holotype ( Fig. 7 ) and the paratype ( Fig. 8 A, B ), together with dwarf males, are deposited in the Zoological Museum of Moscow State University (no. Mg 1213). From the undersides of limestone slabs from seaward lips and cup reef rims, up to 3 m depth, 2.4 km north of East Blue Cut, Bermuda, July 1988, Dr. M.L.H. Thomas (University of New Brunswick) collector. Accompanied on slabs by an occasional specimen of the largely insular species Catophragmus imbricatus and Tesseropora atlantica , and other attached organisms ( Thomas & Stevens 1991), and by Auritoglyptes bicornis ( Aurivillius, 1892) (herein).

Etymology. Named in the honor of Dr. M.L.H. Thomas who discovered the new species and, upon the advice of Dr. Wolfgang Sterrer, provided us with material from Bermuda.

Description: Female. Holotype ( Fig. 7 A ): 1.5 1.0 mm, aperture 0.5 mm long from anterior end of opercular bars to posterior end of comb collar, colour off­white in alcohol. Opercular bars ( Fig. 7 B, C ) approximately 0.38 mm long, 1) equipped with several bifid teeth and simple setae, 2) a pair of small elevations (hillocks), about 1/3 the length from the anterior end, bearing one or two bifid teeth at their tops which are slightly larger than the surrounding bifid teeth, 3) a pair of well­developed, recurved (anteriorly bent) posterior processes having small bifid teeth and simple setae long their lengths but only simple teeth at their tips, 4) followed by a long, typical comb collar and 5) scattered setae and bifid teeth at the posterior end of the aperture.

Lateral surfaces of opercular area sparsely covered with short setae among a dense covering of prominent multifid scales, discernible as fine striations and sparse short setae under light microscopy. Lateral bars absent but a feeble apertural reinforcing bar arises from the anterior end of the opercular bars. The orificial knob lacks setae, teeth and denticles, but has a strongly wrinkled cuticle that appears as a densely striated area ( Fig. 7 A, B ). The region between the knob and the attachment disk is approximately three times its length and also appears densely striated ( Fig. 7 A ). The remainder of the mantle, except for a few scattered teeth along the “carinal” margin, lacks armament. The attachment disk is composed of successive layers of striated cuticle, but whether or not it was calcified is unknown.

The mouthparts are surrounded by a typical saddle­shaped labrum. The mandibles ( Fig. 7 D, E ; 8 A ) support three teeth along the upper half and a comb of 9–12 sharp spines along the lower half of the cutting edge, several long setae at upper and lower margins, and numerous small setae on the surface of the blade. Mandibular palps characteristic of lithoglyptids, with trapezoid distal parts bearing long, smooth setae ( Fig. 7 F ). Superior angle of maxillules ( Fig. 7 G ; 8 B ) with three curved spine­like setae, the upper two longer than the lower one, followed by a notch without spines and an inferior angle supporting a row of small spines; surfaces of blade distally setose, upper setae are longest, with several small setae united into ctenoid scales. Maxillae ( Fig. 7 H ) are typical of lithoglyptids, triangular, with long setae at the tip and smaller setae scattered on the anterior side and along inner margin.

Mouth or first cirri (maxillipeds) ( Fig. 7 I ) consist of a long, curved coxa and a quadrangular basis supporting two rami with indistinct segmentation; the anterior ramus perhaps originally three­segmented and almost twice as long as the apparently two ­ segmented posterior ramus, rami bearing numerous long setae. The four pairs of terminal cirri, and the caudal appendages with the proximal and distal segments bearing one­two setae and four setae respectively ( Fig. 7 J ), are typical for the genus.

The simple dwarf males ( Fig. 7 A ; 8 C, D ) were attached to the side of the female near or on the side of the attachment disk. Their pear or gourd­shaped mantle measures 200– 400 µm long, with an elongated, bent, distal end covered by dense annular striations and bearing a distinct apertural slit.

Affinities. The new species, Armatoglyptes thomasi from Bermuda, is similar to A. habei ( Tomlinson, 1963) from Japan, A. wilsoni ( Tomlinson, 1969) from Koror and Wake I., and A. stirni ( Turquier, 1987) from the E. Atlantic in having opercular bars with a pair of large, recurved (anteriorly hooked) posterior projections. The new species is also similar to A. echinoideus ( Kolbasov, 2000f) from Nauru I. in having a strongly wrinkled cuticle of the orificial knob area, but the latter can be easily be distinguished by the heavy hooked spines found on the posterior projections of its opercular bars. The new species also differs from A. habei in having an unarmed orificial knob and in lacking lateral bars. Armatoglyptes wilsoni and A. stirni also lack these features, but the Koror population of the former has a small elevation supporting a strong bifid tooth about 1/3 the length of each opercular bar from the attachment area, and similar elevations are seen in A. thomasi . The mandible in A. wilsoni is described as having the upper half of the cutting edge supporting three blunt cusps rather than sharp teeth, and the lower half bearing many tubercles rather that a comb of sharp spines, and the maxillules have two rather than three curved spines at the superior angle ( Tomlinson 1969), features that clearly separate it from A. thomasi . The two also have markedly different distributions, A. wilsoni being known from the Indo­West Pacific whereas A. thomasi is known only from Bermuda.

This leaves A. stirni on the eastern side of the Atlantic (near Gibraltar) and, therefore, evidently geographically the closest relative of A. thomasi . However, it generally has the hooked tips of the posterior opercular bar projections bifid rather than simple, and there is no elevation between them and the anterior ends of the opercular bars as there is in A. wilsoni and A. thomasi . In addition, the mandible of A. stirni has denticles between the second and third teeth and a thick and short rather than a long comb of relatively long, thin spines between the third tooth and the inferior angle, which further distinguish it from A. thomasi . Furthermore, A. stirni differs from both A. wilsoni and A. thomasi in having the basis of the first or mouth cirrus longer than wide and the anterior and posterior rami perhaps three and clearly four segmented respectively. Thus, while all these species are more or less closely related, A. thomasi is apparently closer to the Indo­W. Pacific forms, particularly A. wilsoni form Koror, than it is to A. stirni from the E. Atlantic.

Figures

FIGURE 7. Armatoglyptes thomasi gen. et sp. nov. (holotype): A ­ female with attached dwarf male, viewed from right side; B, C, right and left opercular bars respectively; D ­ mandible; E ­ inferior angle of mandible; F ­ mandibular palp; G ­ maxillule; H ­ maxilla; I ­ mouth cirrus; J ­ caudal appendage. Scale bars in µm.

FIGURE 8. Armatoglyptes thomasi gen. et sp. nov., A, B (paratype): C, D ­ dwarf males. A ­ mandible; B ­ maxillule; C, D ­ dwarf males, general view. Scale bars in µm.