Areopaguristes oxyophthalmus ( Holthuis, 1959 )

Ayón-Parente, Manuel, Hendrickx, Michel E. & Lemaitre, Rafael, 2015, Redescription and taxonomic status of Paguristes praedator Glassell, 1937 and P. oxyophthalmus Holthuis, 1959 (Anomura: Paguroidea: Diogenidae), with an emendation to the diagnosis of the genus Areopaguristes Rahayu & McLaughlin, 2010, Zootaxa 3915 (4), pp. 491-509 : 501-507

Areopaguristes oxyophthalmus ( Holthuis, 1959) nov. comb.

( Figs. 4–6 )

Paguristes oxyophthalmus Holthuis, 1959 : figs. 22b, 23.— Baker et al., 1981: 93.— Abele & Kim, 1986: 30 (checklist).— Campos & Sánchez, 1995: 570, fig. 6 a-c.— Calado, 1996: 155.— Perry & Larsen, 2004: unnumbered, fig. unnumbered.— McLaughlin et al., 2005: 244 (listed), 2010: 22.— Wicksten, 2005: 32.— Coelho et al. 2007: 10, tbl 4.— Felder et al., 2009: 1069 (listed).— Merchán-Cepeda et al., 2009: 126.— Lemaitre & Felder, 2012: 69.

Paguristes oxyophtalmus .— Rodríguez-Almaraz & Zavala-Flores, 2005: 290, Fig. 17 (misspelling).

Type material. Holotype (not examined): female (carapace length 6 mm), Coquette, first voyage, about 20 miles NNW of mouth of Coppename River, Suriname, 31 m, 1–5 Apr 1957, RMNH. CRUS D 12586 . Paratypes: 1 male (SL 1.3 mm), 1 ovig female (damaged), off Suriname, 06°48'N, 54°54'W, 12 May 1957, R/V Coquette, sta 28, 46 m, USNM 103272; 1 male (SL 2.2 mm), off Suriname, 06°41'N, 55°27'W, 25 Jun 1957, R/V Coquette, sta 274, 42 m, USNM 103273.

Type locality. About 20 miles NNW of the mouth of the Coppename River, 31 m, 1–5 Apr 1957.

Additional material. USNM holdings: 1 male (SL 2.7 mm), West Delta Lease Area, 500 m N of Platform, Louisiana, United States, 28°44'04''N, 89°44'07''W, 31 Aug 1978, coll. Southwest research Institute for BLM/ MMS, sta 09S, 85 m, USNM 187044; 1 male (SL 1.6 mm), near Morro Castle light and Punta Salinas, Puerto Rico, 18°29'40''N, 66°08'30''W, 3 Feb 1933, Johnson-Smithsonian Deep Sea Expedition, R/V Caroline, sta 16, coll. P. Bartsch, 69–174 m, USNM 267532; 1 male (SL 4.2 mm), Texas, United States, [no date], R/V Oregon II, Cruise 232, sta 21, 73 m, USNM 310863; 1 male (SL 3.8 mm), Gulf of Mexico, United States, 23 May 2000, DGOMB, Gyre R/V, RW-1, 175– 200 m, USNM 310879; 1 male (SL 2.4 mm), Puerto Rico, Caribbean Sea, year 1899, R/V Fish Hawk, USNM 103422; 1 male (SL 4.5 mm), Florida Keys, Dry Tortugas, Florida, United States, year 1934, coll. H. Darby, 82 m, USNM 103430; 1 male (SL 3.1 mm), Texas, Gulf of Mexico, United States, 27°52'N, 92°55'W, 20 Jul 1971, sta 71A 7-34, 192 m, USNM 1089226; 1 female (SL 3.6 mm), Gulf of Mexico, United States, 29°40'30''N, 87°16'W, 11 Mar 1988, NAMES B2, R/V Tommy Munro, sta D 4, 200 m, USNM 1095935; 1 male (SL 3.6 mm), off Mississippi River Delta, Gulf of Mexico, United States, 29°04'56''N, 88°45'31''W, Mar 1988, NAMES B2, R/V Tommy Munro, sta C 3, 150 m, USNM 1095960; 11 males (SL 1.9–5.0 mm), 5 females (SL 1.9–3.9 mm), 7 ovig females (SL 2.1–3.9 mm), NW of Trinidad, Lesser Antilles, Caribbean Sea, R/V Pillsbury, sta P-849, 11°14.5'N, 61°46.2'W, 137–139 m, ot, USNM 1253257.

TCWC holdings: 1 female (SL 3.3 mm), SW Gulf of Mexico, 19°25'N, 95°57'W, 20 Aug 1969, sta 69A 11-60, 201 m, skimmer, TCWC 2-5574; 1 female (SL 3.3 mm), SW Gulf of Mexico, 21°16'N, 96°57'W, 23 Aug 1969, sta 69A 11-76,183 m, skimmer, TCWC 2-5575; 1 male (SL 3.0 mm), SW Gulf of Mexico, 21°30'N, 96°55'W, 23 Aug 1969, sta 69A11-78, 677– 732 m, skimmer, TCWC 2-6536.

Diagnosis. Shield about as long as broad; rostrum broadly subtriangular, blunt, not reaching tip level of lateral projections or basis of ocular acicles. Ocular peduncles long, slender, straight, cornea narrow, tapering anteriorly. Antennal flagellum with long setae ventrally 3–5 articles in length. Third maxillipeds with endopod-exopod joint moderately separated. Carpus and palm of chelipeds each with five strong spines on dorsomesial margin. Dorsal margin of propodus of second pereopods with 4 spines on proximal half.

Redescription. Gills biserial. Shield about as long as broad ( Fig. 4 A), dorsal surface with scattered tufts of setae, and short, transverse rows of spinules on anterior dorsolateral margins. Anterolateral margins sloping. Anterior margins between rostrum and lateral projections concave. Rostrum broadly subtriangular, blunt, shorter than lateral projections; lateral projections each ending in spine. Posterior margin rounded. Anterolateral angles usually with 1 small spine. Branchiostegites each with row of spinules on dorsomesial and distal margins, concealed partially by tufts of long setae.

Ocular peduncles ( Fig. 4 A) slender, slightly compressed medially, about 0.90 length of shield. Cornea weakly dilated, about as long as broad, tapering anteriorly to blunt point; inner dorsal portion with narrowly triangular extension of terminal segment of ocular peduncle. Ocular acicles subtriangular, terminating in strong, narrow spine (occasionally bifid or with small spine basally on lateral margin), separated by approximately 0.40 basal width of 1 acicle.

Antennular peduncles ( Fig. 4 A) exceeding ocular peduncles by 0.50 length of ultimate antennular segment; ultimate and penultimate segments unarmed, with few tufts of long setae; basal segment with small spine on ventrodistal margin, lateral face with moderately strong spine on middorsal margin, distal margin with small spine concealed by long setae.

Antennal peduncles ( Fig. 4 A) with supernumerary segment, long, reaching only slightly beyond distal margin of corneas; fifth segment with scattered tufts of setae on dorsal and ventral surfaces; fourth segment with small dorsodistal spine; third segment with ventrodistal margin produced into strong spine; second segment with laterodistal angle produced and terminating in large corneous-tipped spine, remainder of lateral margin unarmed; mesiodistal angle with strong spine, mesial margin setose; first segment unarmed. Antennal acicles triangular, slightly exceeding distal margin of fourth antennal segment, terminating in single or bifid spine, mesial margin with 2 or 3 spines. Antennal flagella short, slightly longer than shield, consisting of about 18 articles, reaching to tip of chelipeds, each article with long, paired setae ventrally about 3–5 flagellar articles in length.

Mandible without distinguishing characters. Maxillule ( Fig. 5 A) with proximal endite subquadrate, distal endite subrectangular, enlarged distally; endopod with 3 apical bristles on weakly produced internal lobe, external lobe well developed, recurved, about 0.75 length of endopod, externobasal angle with 5 long setae. Maxilla ( Fig. 5 B) with endopod moderately long, exceeding scaphognathite by approximately 0.25 of its length, somewhat inflated basally. First maxilliped ( Fig. 5 C) with endopod elongate, approximately 0.75 length of basal segment of exopod, strongly twisted; flagellum short, 1-segmented, with long marginal plumose setae distally; epipod absent. Second maxilliped ( Fig. 5 D) with basis-ischium fusion incomplete. Third maxilliped ( Fig. 5 E, F) with joints of endopod and exopod moderately separated; basis-ischium fusion incomplete; coxa with 2 small spines distally, partially concealed by long setae; basis usually with 4 small spines; ischium with crista dentata well developed, with 12 teeth, without accessory tooth, and usually 1 small spine on dorsodistal margin; merus with 2 or 3 spines on ventrolateral margin, dorsodistal margin with 1 small spine; carpus, propodus and dactyl unarmed.

Chelipeds ( Fig. 4 B, C) subequal, thickly covered by long hairs. Dactyls each moderately long, 1.50 times as long as palms, terminating in moderately large or large corneous-tipped claw overlapped by fixed finger; cutting edge with row of about 10 unequal teeth; dorsomesial margin with row of strong spines decreasing in size distally; dorsal surface with irregular longitudinal row of spines decreasing in size distally; mesial surface with 2 rows of corneous-tipped spines. Palms each with row of 5 strong spines on dorsomesial margin accompanied by tufts of long setae, dorsolateral margin not well delimited, dorsal surface with 3 or 4 rows of spines accompanied by tufts of long setae, of which 2 extend on fixed finger, ventrolateral surface with several irregular rows of spine-like tubercles; mesial and ventral surfaces convex with some small spine-like tubercles. Carpi each with row of 5 prominent corneous-tipped spines on dorsomesial margin; dorsolateral margin with 4 or 5 smaller spines; ventrolaterodistal angle with 1 small spine. Meri long, about 1.75 times as long as carpi, subtriangular in crossection; dorsal margins with row of tubercles proximally, becoming corneous-tipped spines distally and accompanied with tufts of long plumose setae; ventrolateral and ventromesial margins each with row of spines, smaller on ventromesial margins; ventral faces with plumose setae. Ischia each with row of small spines and tufts of long seteae on ventromesial margins.

Second and third pereopods ( Fig. 6 A–C) slender, similar right from left except slightly in armature, exceeding chelipeds by approximately 0.50 length of dactyls when totally extended. Dactyls long, 1.50–1.60 times length of propodi; dorsal surface with rows of tufts of long setae; mesial and lateral surfaces each with median longitudinal row of setae, longer on mesial surface; ventromesial and ventrolateral margins and ventral surface each with row of tufts of long setae. Propodi 1.20–1.40 times length of carpi; dorsal surface with row of 4 moderately strong spines on proximal half (second) or with only tufts of long setae (third); mesial surface usually with 2 longitudinal rows of long setae; lateral surface with shallow longitudinal sulcus and usually 2 rows of long setae; ventral surface with 1 irregular row of small spiniform granules accompanied by tufts of long setae. Carpi 0.70–0.80 length of meri; dorsal surface with 1 row of spines (second) or 1 or 2 small spines, one distal and other posterior (third), and tufts of long setae; mesial, lateral and ventral surfaces with tufts of long setae. Meri compressed laterally; dorsal surface with row of small spines or spinules concealed partially by tufts of long setae; ventral surface with row of spinules on ventromesial margin (second) or only tufts of long plumose setae (third); mesial and lateral surfaces with few tufts of short setae. Ischia of second pereopods with 1 or 2 small spines dorsally, third pereopods with pair of granules on ventrolateral margin and tufts of long setae. Coxa of second pereopods with 1 small spine ventrodistal. Third pereopods unarmed.

Sternite XII (between third pereopods; Fig. 4 D) with anterior lobe subdivided in 2, each lobe with tufts of long stiff setae. Fourth pereopods ( Fig. 6 D) subchelate; dactyls each 0.60 length of propodus, ventrolateral margin unarmed, with long, slender preungual process; propodal rasp with 2–4 rows of scales at least distally. Carpi and meri unarmed. Fifth pereopods chelate; dactyls each with 2 or 3 rows of small corneous spines; propodi each with well developed propodal rasp bearing several rows of small corneous spines.

Male first and second pleopods modified as gonopods. First gonopod ( Fig. 4 E, F) with tuft of long setae on mesial margin of basal lobe and superior mesial angle, lateral margin of basal lobe naked; inferior lamella with row of long setae on lateral margin, distal margin with row of simple, bifid or multifid curved corneous spines extending on mesial face; external lobe subtriangular, exceeding inferior lamella in distal extention, naked; inner lobe subtriangular, almost as long as inferior lamella, with setae on mesial margin. Second gonopod ( Fig. 4 G) with distal segment longer than basal segment, slightly twisted, with long simple setae on laterobasal margin and distally on lateral and mesial margins; basal segment naked. Left pleopods 3–5 unpaired, each with exopod well developed, endopod vestigial or absent.

Female with paired gonopods, paired first pleopods ( Fig. 4 H), and unpaired left pleopods 2–5; first pleopod usually with 2 setae on basal segment, distal segment with long plumose setae on lateral and distal margins. Pleopods 2–5 lacking brood pouch, with dense long setae.

Uropod and telson strongly asymmetrical. Telson ( Fig. 4 I) with distinct, deep lateral incisions dividing anterior and posterior portions; posterior portion separated in 2 unequal lobes by moderately deep median cleft, terminal margins of lobes each armed with about 5 small corneous-tipped spines, 2 of which on left lobe near lateral margin distinctly larger; anterior and posterior portions with lateral margins sparsely setose.

Color. According to Holthuis (1959: 137), based on preserved material: "a few faint reddish spots are visible on the carapace, while a very small red spot is present in the basal part of the eyestalks. On the chelipeds there is a red band basally on the palm; a red band extends along the external and posterior margin of the upper surface of the carpus and continues on the basal part of the inner surface; a red spot is visible in the antero-internal part of the dorsal surface of the carpus; the merus has a red distal band and shows a red colour in the upper basal part. The ambulatory legs show a red band in the basal and in the distal part of the propodus, carpus and merus, and furthermore in the basal part of the dactylus''.

Habitat. Muddy and muddy-sand bottoms, among shells, mud and shells, and shell and coral debris. Depth: 27–732 m, most frequently found between 20–40 m ( Holthuis 1959; Campos & Sánchez 1995; this study).

Distribution. Western Atlantic: from the Gulf of Mexico and Caribbean Sea, to Pará, Brazil ( Campos & Sánchez 1995; this study).

Remarks. When Holthuis (1959) described Paguristes oxyophthalmus it appears that he was not aware of Glassell´s (1937) description of P. praedator , as he did not include a comparison of the similarities between these two taxa. In both species the second and third pereopods are similarly long and slender, and the dactyls lack spines dorsally and ventrally. However, in A. oxyophthalmus the dactyls are proportionally longer relative to the propodi than in A. praedator . Also, in A. oxyophthalmus , there are four spines on the posterior half of the propodus of the second pereopod, whereas there are usually six or seven (or rarely five) spines in at least larger specimens (SL> 2.5 mm) of A. praedator .

Areopaguristes oxyophthalmus can be distinguished from the four other current western Atlantic congeners primarily by the short, blunt rostrum which does not exceed the lateral projections of the shield. One western Atlantic congener, A. hummi , does have a similarly short rostrum; however, in A. hummi the mesial margins of the ocular acicles are adjacent and each acicle has a multidentate anterolateral margin, whereas in A. oxyophthalmus the acicles are distinctly separated and the anterolateral margin of each acicle is entire.

Figures

FIGURE 4. Areopaguristes oxyophthalmus nov. comb. (Holthuis, 1959). A, C, presumably female holotype (carapace length 6 mm, fide Holthuis 1959), RMNH. CRUS D 12586; E, F, presumably male paratype (SL 2.2 mm), USNM 103273; G, male (SL 4.2 mm), USNM 310863; B, D, H, I, female (SL 3.3 mm), TCWC 2 - 5574. A, shield and cephalic appendages, dorsal view; B, right cheliped, mesial view; C, same, outer view; D, sternite XII (third pereopods), ventral view; E, first pleopod, internolateral view; F, same magnified; G, first pleopod, internolateral view; H, first pleopod; I, telson, dorsal view. Scale bars B, D, H = 1 mm, G = 0.5 mm. (A, C, E, F, redrawn from Holthuis 1959).

FIGURE 5. Areopaguristes oxyophthalmus nov. comb. (Holthuis, 1959). Female (SL 3.3 mm), TCWC 2 - 5574. Left mouthparts, inner view. A, maxíllule; B, maxilla; C, first maxilliped; D, second maxiliped (setae omitted); E, third maxilliped (setae omitted); F, ischium and merus of third maxilliped, outer view (setae omitted). Scale bars = 0.5 mm.

FIGURE 6. Areopaguristes oxyophthalmus nov. comb. (Holthuis, 1959). A, B, D, female (SL 3.3 mm) (TCWC 2 - 5574); C, presumably female holotype (carapace length 6 mm, fide Holthuis 1959), RMNH. CRUS D 12586. A, second right pereopod, lateral view; B, third right pereopod, lateral view; C, third left pereopod, lateral view; D, dactyl and propodus of fourth left pereopod, lateral view (setae omitted). Scale bars: A, B = 2 mm, D = 1 mm. (C, redrawn from Holthuis 1959).