Eduarctus reticulatus, Holthuis, 2002Gibbularctus, Holthuis, 2002

Holthuis, Lipke B., 2002, The Indo-Pacific scyllarine lobsters (Crustacea, Decapoda, Scyllaridae), Zoosystema 24 (3), pp. 499-683 : 619-623

publication ID	https://doi.org/ 10.5281/zenodo.4689240
persistent identifier	https://treatment.plazi.org/id/03EF4243-FF80-FFD9-FCC7-5451C529FCCC
treatment provided by	Felipe
scientific name	Eduarctus reticulatus Gibbularctus
status	sp. nov.

Treatment

Eduarctus reticulatus View in CoL n. sp.

( Figs 48-50 View FIG View FIG View FIG ; 69B View FIG )

TYPE MATERIAL.— Holotype: 20 mm, RV Cape St. Mary , cruise 3/64, stn 48 ( RMNH D 49578). For paratypes see Material examined.

TYPE LOCALITY.— South China Sea. Macclesfield Bank, 15°36.8’N, 114°15.4’E, 73- 84 m.

ETYMOLOGY.— The new specific name refers to the reticulate pattern formed by the dense placement of the tubercles on most parts of the body, even on the usually smooth anterior half of the abdominal somites.

MATERIAL EXAMINED.— Seychelles. REVES 2, stn 21, 5°21.8’S, 56°10.4’E, trawl, 55-60 m, sand with calcareous algae (melobesiids), bottom almost flat, 6.IX.1980, 1 paratype 17 mm (photographed, MNHN-Pa 1833). — Stn 27, 4°55.6’S, 54°58.5’E, trawl, 53 m, sand with calcareous algae (melobesiids) and coral, bottom flat, 8.IX.1980, 1 paratype 14 mm (MNHN-Pa 1834). South China Sea. Macclesfield Bank. RV Cape St. Mary, cruise 3/64, stn 48, 15°36.8’N, 114°15.4’E, trawl No. 169, 73-84 m, coral bottom, 17.VI.1964, A. J. Bruce leg., 1 holotype 20 mm ( RMNH D 49578). — HMS Egena , 64-75 m, P. Bassett Smith leg., 1 paratype 12 mm (BM 93.11.3. 30/31). — 70 m, P. Bassett Smith, 2 paratypes 8 and 9 mm (BM 92.8.28. 53/54). Chesterfield Islands. CHALCAL 1, stn DC 55, 21°23.9’S, 158°59.6’E, trawl, 55 m, Halimeda and Foraminifera, 25.VII.1984, 1 ov. paratype 17 mm, 1 juv. paratype 5 mm, 1 juv. paratype 9 mm (MNHN-Pa 771). — Île Longue, diving, 33 m, sand, 16.X.1986, P. Laboute, 1 soft paratype 12 mm (MNHN-Pa 1267). — AMUSIUM 1, station number unknown, depth probably about 60 m, date unknown, 1 paratype 16 mm (MNHN-Pa 1836). Lansdowne Bank. 1.VIII.1988, 1 ov. paratype 16 mm (MNHN-Pa 1335). New Caledonia. LAGON, stn 398, Grand Récif Sud, 22°37.0’S, 167°11.8’E, 71 m, coarse sand, Foraminifera and Gorgonaria, 23.I.1985, 1 ov. paratype 18 mm ( RMNH D 48758). SMIB 8, stn DW 186, Banc Aztèque, 23°24.9’S, 168°05.7’E, 57-59 m, 31.I.1993, 1 paratype 12 mm (photographed, MNHN-Pa 1835).

DISTRIBUTION.— So far this species is only known from the present material from the Seychelles, South China Sea and New Caledonia. It is likely that it eventually will also turn up in localities in-between.

HABITAT.— The species has been collected at depths between 33 and 73(-84) m, on flat sandy bottoms often with corals, Gorgonaria, calcareous algae, Halimeda and Foraminifera.

DESCRIPTION

The species is very close to E. modestus n.comb., especially as far as the shape of the lateral margin of the carapace is concerned. There are, however, several differences which make it necessary to consider this a new species.

There is no rostral tooth, the rostrum does bear dorsally a blunt tubercle. The pregastric and gastric teeth both are distinct and somewhat triangu-

lar in lateral view. The cardiac tooth is distinctly blocked by a large tubercle, followed by a smaller. triangular in lateral view, it is less elevated than in At either side of the anterior postrostral carina E. modestus n.comb. and is flanked at either sideand just before the cervical groove is a smooth, by a tubercle, which reaches farther forward than slightly sunken area without tubercles; this area the cardiac tooth itself; in lateral view this often is of a dark colour.

tubercle shows below the cardiac tooth. The anterior end of the posterolateral carina ends The branchial ridge is interrupted by the cervical in a strong tooth, which is placed slightly higher groove, which, however, just mediad of the gap is and slightly in advance of the posterior end of the

mediolateral carina. The lateral margin thereby is interrupted and makes a distinct angle here. There are three or four anterolateral, three or four mediolateral and eight or nine posterolateral teeth, which as a rule are very distinct.

The marginal groove along the posterior margin of the carapace is very narrow, the tubercles of the row before it and those behind it almost touch. The tubercles before and behind are numerous and not or not distinctly arranged in transverse rows.

Through the presence of numerous flattened tubercles, the upper surface of the body gives a somewhat reticulated impression.

The surface of the anterior half of the abdominal somites II to IV shows a reticulation of shallow hairy grooves. The posterior half of somite I shows about 20 longitudinal grooves, which are quite irregular and branched, often forming a reticular pattern of small tubercles. The median carinae of somites II to V are very low and inconspicuous, mostly they are not grooved, except that of somite II that may show such a longitudinal groove. Laterally the carina are somewhat lobulated. The carina of somite III is highest, that of somite IV is lowest, while the one of somite V is hardly elevated at all.

The anterior margin of the antennular somite has a median incision at either side of which there are four low broad lobes.

The sixth (last) antennal segment has four or five truncated teeth, only the inner being somewhat triangular; the inner margin of the segment shows two small triangular appressed teeth. The fourth segment has the anterior margin with about seven low and rather wide teeth, the inner of which is the most conspicuous. The lateral margin of the fourth segment has two or three large and sharp teeth (the apical tooth of the segment not included) and one or two much smaller incisions. The median oblique carina of the segment bears eight to 12 rather irregularly arranged tubercles; the outer half of the dorsal surface of the segment shows a curved row of eight to 10 rather large tubercles, which become smaller distally; there are also scattered tubercles on the rest of the surface.

The propodus of the third leg has a fringe of very short hairs on the upper and lower margins. In one specimen the outer surface of the propodus of the right third leg has a hairy longitudinal groove in the basal part just above the lower margin; in the left leg this groove is absent. A sunken longitudinal hairy groove is present on the outer surface of carpus and merus of legs 3 to 5. The merus of legs 1 to 3 has a lower carina. The fixed finger of the chela of the fifth leg of the adult females is half or less than half as long as the dactylus.

The anterior margin of the thoracic sternum has the normal shape as found in this genus: it is shallowly emarginate with a median incision that is flanked by a pair of low tubercles. The margin is thickened and from either anterolateral tooth a broad, low carina extends posteriorly and inward; these two carinae do not meet in the middle, in the space between them there are several small tubercles. The entire surface of the sternum is covered by low irregular tubercles and shallow short grooves. The posterior margins of the somites bear each a transverse row of small tubercles; on somites II, III and IV the median of these tubercles is slightly the largest.

The first pleopod of the male (namely that of abdominal somite II) from the Seychelles has the endopod and exopod narrow but distinct; the exopod is elongate oval and blunt, the endopod is slightly longer and ends in a rather sharp point, its anterior margin is straight, the posterior convex. In the following pleopods the exopod is broadly oval, the endopod reduced to a knob.

Size

The males have a carapace length between 12 and 14 mm, non-ovigerous females between 12 and 20 mm, and ovigerous females between 16 and 18 mm; juveniles with cl. 5 and 9 mm have been observed; the largest non-ovigerous female (the holotype) evidently was ovigerous shortly before as the pleopods still carry ovigerous setae.On the whole this species is larger than E. modestus n.comb.

Colour

A coloured photograph of the female from the Banc Aztèque shows the carapace of a pale greyish brown colour, partly covered with conspicuous spots. The dark smooth spot just before the cervical groove and between the anterior postrostral and anterior branchial carinae has already been mentioned. Between this spot and the posterior margin of the orbit extends a broad bright white band. Some small bright white spots are on the anterior part of the posterior branchial carina. The lateral margin of the carapace shows dark purple, extending over the full length of the carapace and even touching the postero-lateral angle of the fourth antennal segment. Many of the tubercles on the antenna are white, while there also are white areas in the basal part and along the anterior and outer margins of the antenna, the rest is pale purple. The abdomen is variegated purple and bright white; the white colour is most conspicuous in the anterior median region; the fifth segment is almost entire- ly purplish. The sixth segment and the tailfan show as of an evenly whitish or pale purplish gray colour. Not shown on this photograph, because the animal is fully stretched, but what can be observed in rather fresh alcohol specimens is a row of four rather large rounded dark spots on the anterior half of the first somite. Furthermore such alcohol specimens also show a dark spot on the posterolateral angle of the sixth antennal seg- ment and a rather broad dark band in the basal half of the propodi of P.3 to P.5, but not in the other segments of these legs. Genus Gibbularctus View in CoL n. gen.