Maoridotea naylori Jones & Fenwick 1978

“Maoridotea naylori sp. nov.

Holotype: Male, 12^.40 mm long (slightly damaged and lost tip of pleotel­son), NMNZ (Wellington) Cat. No. Cr 2169. Eastern end of Wairepo Flats, Kaikoura, N.Z. (42°25^.7'S, 173°42^.8'E). 10 July 1976. Coll. M. B. Jones. Free swimming among Hormosira banksii (Phaeophyta).

Paratypes: (1) One female, 5^.75 mm long, NMNZ (Wellington) Cat. No. Cr 2170. One male, 10^.85 mm long, BM (NH) (London) Cat. No 1977 : 360. New Wharf, Kaikoura, N.Z. (42°25'S, 173°42'E). 25 August 1972. Coil. unknown. Attracted to surface at night by light.

(2) One male, 11^.90 mm long, three females (two ovigerous), 8.89-10.47 mm long, NZOI (Wellington) Cat. No. P 344-7. One male, 12^.38 mm long, three females (two ovigerous), 9-21-10^.16 mm long, A.M. (Sydney) Cat. No. P. 25533. One male, 11^.27 mm long, three females (two ovigerous), 8.25-10.79 mm long, NMNH (Washington, D.C.) Cat. No. USNM 170585. South Bay, Kaikoura, N.Z. (42°25^.8'S, 173°41^.2'E). 22 October 1977. Coll. G. D. Fenwick. In coarse shelly sand, 3 m depth.

Holotype: Male, 12^.40 mm long. Cephalon (fig. 1) broad, antero-lateral margins entire, broadly rounded, posterior margin rounded; eyes lateral. Body (figs. 1 and 2) flattened, dorsally rounded, smooth, tapering posteriorly; peraeonite 3 widest; coxae (fig. 2) present on peraeonites 5-7, subtriangular to subquadrate. Pleon of four somites and pleotelson.

Antenna 1 (fig. 8) peduncle article 1 stout, with a latero-proximal group of small spinules, distal margin straight with several setae; article 2 0^.8 as long as 1, slightly expanded distally, with two oblique rows of setae medially, a longitudinal ventral row and a transverse distal row; article 3 long and slender, both ends slightly expanded, bare but for a distal row of short setae; flagellum (fig. 9) biarticulate, second article minute, both with setae and aesthetases. Antenna 2 (fig. 10, first article not included in figure) stout, subequal to 1; peduncle article 3 about twice as wide distally as proximally, median margin convex with several setae, distal margin with a small group of setae; article 4 1^.5 times wider than long with numerous latero-distal setae; article 5 long, widened distally, distal margin deeply concave, several setae along median and lateral margins; flagellum ten-articulate, each article with a medio-distal group of setae and a single latero-distal seta.

Mandible (figs. 3 and 4) stout, broadly rounded posteriorly, anterior margin with large ' ball ' process which fits a labral ' socket '; incisor process rounded, entire, heavily calcified, adjacent to molar process; lacinia mobilis absent; molar process very large, smooth, almost flat, heavily calcified, a short setal row dorsally. Maxilla 1 (fig. 5) outer plate elongate, distal margin straight, oblique, with ten stout, blunt setae, one seta just proximal to distal edge; inner plate about 0^.3 as long as outer, distal margin oblique with three long, plumose setae. Maxilla 2 (fig. 6) plates subequal in size and shape, distal edge oblique, rounded; inner plate with a latero-distal group of blunt setae merging with two rows of stouter plumose setae medially; middle and outer plates with single row of setae distally. Maxilliped (fig. 7) inner plate distally truncate with two distal rows of setae and three medio-distal plumose setae, one coupling hook distal of midpoint, narrowed distal of palp attachment; palp five-articulate, article 1 short, wider than long, palp article 2 widened and oblique distally, longer inner margin strongly setose, article 3 0^.3 wider than long, expanded medially into a rounded lobe with several setae, concave distally, lateral margin convex, latero-distal angle free, article 4 elongate expanded disto-medially into a rounded setose lobe, one latero-distal seta, article 5 rounded distally with several setae; outer plate as long as inner, subtriangular, lateral angle broadly rounded.

Peraeopod 1 (fig. 11) stout, subchelate; basis elongate; ischium subtriangular, a few antero-distal setae; merus wider than long, expanded and produced antero-distally into a lobe overhanging carpus, with a group of setae, posterior margin with few setae; carpus short, subtriangular with several postero-distal setae; propodus slightly inflated, few distal setae, posterior margin almost straight with several long and short, stout setae, dactylus hinge large; dactylus stout, slightly curved, tip with two stout, blunt spines. Peraeopod 2 (fig. 12) subchelate, differs from 1 as follows: slightly larger size, ischium and merus longer and with more setae, tip of dactylus with a large blunt spine and a smaller posterior spine. Peraeopod 3 (fig. 13) subchelate, differs from 2 as follows: slightly greater length of all articles, merus median surface densely covered with long plumose setae forming a large median ' brush '. Peraeopod 4 (fig. 14) simple, stout; basis margins weakly convex, posteriorly fringed with setulae, three short setae antero-distally; ischium expanded posteriorly with several setae, anterior margin with middle and distal setae groups; merus short, widened distally, anterior and posterior margins with middle and distal setae; carpus subrectangular, sparse setae posteriorly, anterior edge with a group of setae, a distal row of setae; propodus elongate, posterior edge with few setae, two anterior groups of setae, a distal row of setae; dactylus long, stout, tip with a large blunt spine. Peraeopods 5-7 similar to 4 but larger, 6 largest, some slight differences in setation.

Pleopod 1 (fig. 15) exopod subovate, lateral margin weakly concave, lateral, distal and disto-median margins with long setae; endopod subequal to exopod, lateral margin distinctly concave, median, distal and disto-lateral margins with long setae. Pleopod 2 (fig. 16) similar to pleopod 1 except: setae confined to distal margin of endopod, medio-proximal corner lobed bearing appendix masculina; appendix masculina 1^.5 times longer than endopod, narrow, curved, tip rounded. Pleopod 3 (fig. 17) exopod and endopod similar to pleopod 2, endopod lacking medio-proximal lobe. Pleopod 4 (fig. 18) exopod subovate, bare, tip narrowly rounded; endopod biarticulate, both articles with median setulae, article 2 with a single plumose seta. Pleopod 5 (fig. 19) as in 4 but endopod lacking terminal seta. Uropod (fig. 20) peduncle operculate, subovate, with a single distal seta; outer ramus ovate, fringed with setae distally and laterally; inner ramus longer than outer, tapering, obliquely truncate with distal setae. Penes (fig. 21) extending from midline of last thoracic segment over abdomen.

Paratype female: 5^.75 mm long. Differs from holotype as follows: antennae, peraeopods and uropod with fewer setae, and pleopod 2 no median lobe on endopod and no appendix masculina. Antenna 1 article 3 stout, almost as wide as article 2. Antenna 2 flagellum six-articulate. Peraeopods 1-3 with a few long slender setae only on palm; peraeopod 3 merus without a dense ' brush ' of long plumose setae. Peraeopods 4-7 more slender; dactylus with one blunt terminal spine almost as long as dactylus; peraeopods 4-5 dactylus less than half as long as propodus; peraeopods 6-7 dactylus about half as long as propodus. Uropod peduncle lacking long terminal seta.

Variation: No variation was apparent between the male specimens, or between the females. Differences between the holotype male and the paratype female show sexual dimorphism in this species. Juveniles released from some ovigerous females during fixation were 2^.08-2-32 mm long and closely resemble the adult specimens. However, the following differences were observed: rostrum poorly developed; all appendages relatively stouter than on the adult; flagellum of antenna 2 four-articulate; dactyls of peraeopods 1-6 less than one-third as long as propodus, each with one terminal seta about equal in length to propodus; peraeopod 7 not developed; no sexual characters; body lacking pigmentation.

Remarks: The tip of the telson was drawn from the paratypes, otherwise all illustrations are of the holotype.

Members of the Chaetilinae occur from the intertidal to 309 m, and are characteristically sand bottom dwellers (see the table). M. naylori occurs abundantly in clean, coarse shelly sand in conditions of moderate wave exposure. When disturbed it burrows rapidly beneath the surface where it remains hidden.

Maoridotea naylori is named after Professor E. Naylor, Department of Marine Biology, University of Liverpool, Isle of Man, U.K., in recognition of his work on the biology of idoteid isopods.”

(Jones & Fenwick, 1978: 618-625)

Maoridotea naylori là một loài chân đều trong họ Chaetiliidae. Loài này được Jones & Fenwick miêu tả khoa học năm 1978.