Garthambrus tani Ahyong, 2008

Mclay, Colin L., 2009, Revision of the crab genus Garthambrus Ng, 1996, with the description of two new genera and discussion of the status of Tutankhamen Rathbun, 1925 (Crustacea: Brachyura: Parthenopidae), Zootaxa 2122, pp. 1-50 : 22-30

Garthambrus tani Ahyong, 2008

( Figs 8 A, B, 14)

Tutankhamen sp — Clark & O’Shea 2001: 15. – Martin & Haney 2005: 451, 497. Not Tutankhamen Rathbun, 1925 . Garthambrus tani Ahyong, 2008: 55 , figs 25–27.

Types examined. PARATYPES: 1 male, 17.8 x 13.4 mm, 1 ovig. female, 11.7 x 8.2 mm (NIWA 34979), off Curtis I., Kermadec Is, stn K840, 30°17.59’S, 178°25.30’W, 398–412 m, 28 Jul 1974.

Material examined. New Caledonia. VAUBAN, stn DC22 (sample also registered as CB113), 22° 59.00S, 167° 17.00E, 540–545 m, 12 Apr 1978: 1 male 28.5 x 21.2 mm, 1 female, 22.8 x 16.3 mm (MNHN-B31879).

MUSORSTOM IV: stn 197, 18º51.3’S, 163º21.0’E, 550 m, 20 Sep 1985: 1 male 25.6 x 19.3 mm, 1 female 18.5 x 14.2 mm (MNHN-B31880); Stn 215, 22º55.7’S, 167º17.0’E, 485–520 m, 29 Sep 1985: 1 male 22.0 x 16.4 mm (MNHN-B31881); Stn 216, 22º59.5’S, 167º22.0’E, 490–515 m, 29 Sep 1985: 1 female 21.0 x 15.1 mm (MNHN-B31882).

BIOCAL: stn DW66, 24º55’S, 168º22’E, 505–515 m, 3 Sep 1985: 1 female 7.2 x 5.7 mm (MNHN).

SMIB 2: stn DW11, 22º57.1’S, 167º18.3’E, 475–500 m, 18 Sep 1986: 1 male 25.9 x 18.8 mm (MNHN).

CHALCAL II: stn DW 72, 24º54.50’S, 168º22.30’E, 527 m, 28 Oct 1986: 1 male 22.7 x 16.6 mm, 1 female 7.4 x 5.9 mm (MNHN); Stn DW73, 24º39.9’S, 168º38.10’, 573 m, 29 Oct 1986: 1 male 15.4 x 11.4 mm, 3 females 7.4 x 5.8–14.2 x 10.5 mm (MNHN); Stn DW74, 24º40.36’S, 168º38.38’E, 650 m, 29 Oct 1986: 4 males 11.1 x 8.7–17.0 x 12.7 mm, 5 females 10.5 x 8.0–15.1 x 11.5 mm (MNHN); Stn DW75, 24º39.31’S, 168º39.67’E, 600 m, 29 Oct 1986: 5 males 11.3 x 8.9–17.7 x 12.8 mm, 4 females 10.0 x 7.3–14.5 x 11.3 mm (MNHN); Stn DW76, 23º40.5’S, 167º45.2’E, 470 m, 30 Oct 1986: 3 females 17.4 x 12.8–22.7 x 16.4 mm (MNHN); Stn DW77, 23º38.35’S, 167º42.68’E, 435 m, 30 Oct 1986: 1 female 10.7 x 8.1 mm (MNHN).

SMIB 3: stn DW01, 24º55.7’S, 168º21.8’E, 520 m, 20 May 1987: 2 males 15.9 x 12.0, 18.8 x 13.6 mm (MNHN); Stn DW02, 24º53’S, 168º22’E, 530-537 m, 20 May 1987: 1 male 25.6 x 19.0 mm, 1 female 16.3 x 11.7 mm (MNHN).

SMIB 4: stn DW39, 24º56.2’S, 168º21.5’E, 560 m, 7 Mar 1989: 1 male 18.0 x 13.0 mm, 1 female 36.4 x 24.2 mm (MNHN).

BERYX 11: stn CP08, 24º54’S, 168º21’E, 540–579 m, 15 Oct 1992: 1 male 17.1 x 13.0 mm (MNHN); Stn DW10, 24º53’S, 168º21’E, 565–600 m, 15 Oct 1992: 5 males 6.9 x 5.8–20.2 x 15.0 mm, 5 females 6.9 x 5.8–13.3 x 10.4 mm (MNHN); Stn DW27, 23º37’S, 167º41’E, 460–470 m, 18 Oct 1992: 1 female 18.1 x 14.0 mm (MNHN); Stn DW38, 23º38.5’S, 167º39.0’E, 550–690 m, 19 Oct 1992: 1 female 19.4 x 15.1 mm (MNHN).

SMIB 8: stn DW146, 24º55.2’S, 168º21.7’E, 514–522 m, 27 Jan 1993: 1 male 11.6 x 8.8 mm (MNHN); Stn DW148, 24º55.1’S, 168º21.6’E, 510 m, 27 Jan 1993: 1 female 10.1 x 7.7 mm (MNHN); Stn DW 149, 24º54.9’S, 168º21.8’E, 508–510 m, 27 Jan 1993: 2 males 10.1 x 7.7, 10.3 x 8.4 mm, 2 females 7.0 x 5.5, 10.0 x 7.3 mm (MNHN); Stn DW153, 24º55.5’S, 168º21.3’E, 547–560 m, 27 Jan 1993: 1 male 20.2 x 14.9 mm (MNHN); Stn DW164, 24º49.0’S, 168º08.7’E, 300–350 m, 28 Jan 1993: 1 male 12.6 x 9.3 mm, 1 female 13.8 x 10.7 mm (MNHN).

BATHUS 2: stn DW720, 22º51.62’S, 167º16.40’E, 530–541 m, 11 May 1993: 1 ovig. female 22.2 x 16.4 mm (MNHN); Stn CP735, 23º01.77’S, 166º56.10’E, 530–570 m, 13 May 1993: 1 male 19.9 x 14.7 mm (MNHN).

BATHUS 3: stn CP833, 23º03’S, 166º58’E, 441–444 m, 30 Nov 1993: 1 male 11.2 x 8.8 mm (MNHN).

HALIPRO 1: stn CP877, 23º3’S, 166º59’E, 464–480 m, 31 Mar 1994: 1 male 10.3 x 8.1 mm (MNHN).

SMIB 10: stn DW206, 24º56’S, 168º21’E, 555– 548 m, 10 Jan 1995: 1 male 14.5 x 10.6 mm (MNHN).

Description. Carapace wider than long, ratio CW/CL = 1.3, sub-pentagonal, covered with fine, rounded granules. Median rostral tooth narrowing anteriorly, blunt tip bent slightly upwards; lateral rostral teeth truncate. Frontal region centrally concave. Dorsal orbital margin slightly swollen, interrupted by small depression. Protogastric region convex, bearing 2 distinct tubercles near mid-line. Meso-, metagastric regions with narrow medial interrupted ridge, but no tubercles. Cardiac region slightly pitted, eroded with prominent blunt posterior tubercle. Intestinal region with broad blunt tubercle, which may be bifid, behind cardiac tubercle. Anterior branchial region dominated by broad posterior diagonal ridge not reaching posterior epibranchial margin but ends in prominent blunt tubercle. Ridge may have some eroded areas. Posterior branchial region has prominent tubercle overhanging posterior epibranchial margin. Three pits in branchiocardiac groove but no solitary tubercle. Eight carapace tubercles.

Orbital margin finely granular, very concave to distinct supraorbital suture. Suborbital margin ends in subacute tooth. Posterior corner of hepatic margin projecting, with small tubercle. First anterior epibranchial tooth close to hepatic border, followed by 10 distinct blunt teeth which tend to decrease in size posteriorly. Posterior epibranchial corner is flange-like. Anterior epibranchial teeth tend to be curved upward. Posterior epibranchial margin slightly concave, single distinct tooth behind posterior epibranchial corner. Posterior margin with 3 well developed, blunt teeth, one at each corner, one in middle.

Epistome T-shaped, shallow central depression separated from lateral depressions by narrow ridge on each side. Subhepatic region concave with deep fissure running from corner of buccal frame towards first anterior epibranchial tooth. Cheliped-blocking mechanism involves large proximal meral spines meeting spine on sub-branchial area. Sternites 3, 4 of males with shallow V-shaped area impressed upon them with large tubercle at each corner, following sternites without ridges developed at lateral corners. In females these areas are taken up by abdomen. Only thoracic suture 6/7 complete.

Eyes mobile, eyestalks granular, short, diameter same as cornea; margin of orbit incomplete ventrally, orbital fossa deep, formed by lateral, suborbital margin, around 80% of cornea concealed when eye is folded away.

Antennular article 1 mobile, 6-sided; article 2 much longer than wide, inserted medially, folded away at an oblique angle; article 3 much longer than wide; articles 3, 4 normally kept folded away in antennular fossa.

Antennal article 1 (“urinal article”) mobile, wider than long, convex; article 2 (often called “basal article”) trapezoidal, convex, fixed to epistome, suborbital margin; articles 3, 4 mobile, longer than wide; flagella as long as articles 3, 4 combined.

Basis-ischium of third maxilliped with blade-like medial margin which is sinuous in part. Depressions on merus separated by ridge which has at least one large, several small tubercles. Disto-lateral corner of merus covers distal end of exopod, bears small tubercle. Only carpal article of palp exposed.

Inner border of cheliped merus has 9 blunt tubercles with many smaller ones interspersed; outer border has 8–10 subacute tubercles with, median group of 3 tubercles curving down from upper to lower surface, most distal tubercle largest, most acute. Cheliped carpus has one prominent subacute median spine. Outer border of propodus has 8 or 9 irregular tubercles; inner border with 8 tubercles, last 5 curving up toward base of dactyl. Dactyl with two or three small tubercles decreasing in size distally. Right cheliped a crusher; left a cutter.

Walking legs decrease in length posteriorly. Ornamentation on legs as follows: P2: merus 4/(1 + 0); P3: merus 4/(4 + 3); P4: merus 5/(4 + 3); P5: merus 7(3 + 3). Crest-like ridges on first 3 articles of P2 to P5, but on meri these sometimes interrupted, broken into flattened regions, so that there can be toothed, crested regions on same article. Dactyli shorter than propodi.

Lateral parts of third abdominal segment have small tubercle while central part is depressed. Fourth to sixth segments have central ridge. Third to fifth segments fused in male, only suture 4/5 evident near margins. Small median tubercle on segment 6 in male, absent in female. Abdominal locking mechanism effective in male, but in mature females although button, socket present, abdomen too broad, convex to work effectively. Telson wider than long, tip truncate in male more rounded in female. Telson of mature female covers most of sternite 4.

G1 reaches anterior border of sternite 5 in situ, narrows quickly to straight section, sperm aperture opens medially, tip has many very small, acute spines directed proximally. Spines cover last 14% of length of G1. G 2 in situ slightly longer than G1, flagella twisted, occupying 52% of length. Transition from calcareous proximal section to flexible flagella not marked by notch. Ratio of length of G2/G1 = 1.3. Female gonopore mid-way on sternite 6, oval in shape, lips raised above sternal surface, hinged laterally, sealed by flexible cover.

Distribution. Known from New Caledonia, Kermadec Is and New Zealand.

Remarks. This species was recently described by Ahyong (2008) from the Tumokemoke Seamount and from Curtis I., Kermadec Is, who had corresponded with us with regards to the new species (in manuscript), but considered that his specimens from New Zealand were different from our material. He believed that the key difference was that the New Zealand specimens had stellar paxillate carapace tubercles rather than the granulate tubercles typically seen in New Caledonia, but the variation seen in our much larger sample encompasses the New Zealand specimen. We are convinced that it belongs to the same species found in New Caledonia, so Ahyong’s name has priority. Some of the features included in the present study of Garthambrus were not given by Ahyong (2008) so for the sake of consistency we include our description here. Garthambrus tani is the first parthenopid recorded from New Zealand.

Garthambrus tani bears some resemblance to G. s t e l l a t u s in that both species have well-defined teeth on the upper margin of the ambulatory legs and the epibranchial teeth is distinct and pointed at the tips.

Garthambrus tani can be differentiated from G. s t e l l a t u s in that some of the teeth on the upper margin of the ambulatory legs are fused with adjacent members. In G. stellatus , the teeth are always distinctively separated. In addition, G. stellatus has a densely tuberculate carapace, but the carapace is less tuberculate in G. t a n i.

Figures

FIGURE 8. Gonopods. Garthambrus tani Ahyong, 2008: A, B, male 28.5 x 21.2 mm (MNHN), New Caledonia, VAUBAN, stn CB 113, 500 m, 12 Apr 1978. — Garthambrus undulatus sp. nov.: C, D, holotype, male 44.4 x 29.0 mm (MNHN), New Caledonia, VOLSMAR, stn DW 30, 22 ° 17.0 ’ S, 171 ° 17.7 ’ E, 550 m, 5 Jun 1989. A, C, left G 1; B, D, left G 2. Scale bar = 1 mm.