Guinope tiara, Thoma & Felder, 2020

Thoma, Brent P. & Felder, Darryl L., 2020, A new genus and species of xanthoid crab (Decapoda: Brachyura) from offshore hard bank habitats in the Gulf of Mexico, Zootaxa 4731 (3), pp. 403-413 : 405-411

Guinope tiara n. gen., n. sp.

( Figs. 1 A–M; 2A–D)

Garthiope barbadensis, Thoma et al. 2009 : tab. 2, figs 1 & 2, 563. Not Garthiope barbadensis ( Rathbun, 1921) .

“Gen. nov., sp. nov. near Garthiope barbadensis”, Thoma et al. 2014: 90 , tab. 1.

“nov. gen. nov. sp. near Garthiope barbadensis ”, Thoma et al. 2014 : fig. 1, 92.

“New genus nr. Garthiope ”, Lai et al. 2011: tab. 1, fig. 1, 421, 422, 432, 442.

Type material. Northern Gulf of Mexico: Holotype: male, cw 4.2 mm, Sackett Bank , Louisiana, 28° 37.81´N, 89°

33.32´W, 63–65 m, 28 June 2006, USNM 1577453 (= ULLZ 8183 , part, genetic voucher). Paratypes: 2 males, cw 3.4, 3.6 mm, 1 ovigerous female, cw 3.9 mm, Sackett Bank, Louisiana, 28° 37.81´N, 89° 33.32´W, 63–65 m, 28 June 2006, USNM 1543543 (= ULLZ 8183 , part, photograph voucher) ; 1 male, cw 2.2 mm, 3 females, cw 2.6, 3.2, 3.4 mm, Sackett Bank, Louisiana, 28° 37.81´N, 89° 33.32´W, 63–65 m, 28 June 2006, USNM 1543552 (= ULLZ 8210 ) ; 1 male, cw 4.2 mm, 1 female, cw 4.0 mm, Sackett Bank, Louisiana, 28° 37.89´N, 89° 33.27´W, 63–68 m, 28 June 2006, USNM 1577531 (= ULLZ 18299 ) ; 1 ovigerous female, cw 4.0 mm, Sackett Bank, Louisiana, 28° 38.033´N, 89° 33.387´W, 61–71 m, 7 September 2014, USNM 1549376 (= ULLZ 16150 , photograph voucher) ; 3 males, cw 2.8, 3.7, 4.0 mm, 1 female 3.2 mm, Sackett Bank, Louisiana, 28° 38.125´N, 89° 33.478´W, 60–61 m, 2 December 2010, USNM 1547191 (= ULLZ 13760 ) ; 1 ovigerous female, cw 4.5 mm, Sackett Bank, Louisiana, 28° 38.047´N ; 89° 35.826´W, 58–80 m, 24 August 2012, USNM 1547740 (= ULLZ 14552 , photograph voucher) ; 1 male, cw 6.9 mm, off Alabama, 29° 24.43´N, 87° 58.63´W, 72-74 m, 29 June 2006, USNM 1543895 (= ULLZ 8581 , photograph voucher) ; 1 male, cw 3.3 mm, 1 female, cw 2.8 mm, off Alabama, 29° 19.57´N, 87° 46.29´W, 96–106 m, 30 June 2006, USNM 1543550 (= ULLZ 8208 ) ; 6 males, cw 3.1–3.8 mm, 5 females (1 ovigerous), cw 2.3–5.8 mm, off Alabama, 29° 24.61´N, 87° 58.62´W, 71–73 m, 29 June 2006, USNM 1543544 (= ULLZ 8191 ) ; 1 male, cw 5.0 mm, off Alabama, 29° 24.61´N, 87° 58.62´W, 71–73 m, 29 June 2006, USNM 1547121 (= ULLZ 13266 genetic voucher) ; 1 male, cw 3.7 mm, 2 females, cw 5.6, 5.8 mm, off Alabama, 29° 24.43´N, 87° 58.63´W, 72–74 m, 29 June 2006, USNM 1543849 (= ULLZ 8173 , photograph voucher) ; 4 males, cw 3.1, 3.8, 4.4, 4.9 mm, 1 female, cw 5.1 mm, off Alabama, 29° 24.43´N, 87° 58.63´W, 72–74 m, 29 June 2006, USNM 1543542 (= ULLZ 8170 , genetic voucher) ; 2 males, cw 4.3, 5.2 mm, 3 females, cw 5.9, 3.7, 3.4 mm, off Mississippi-Alabama border, 29° 15.68´N, 88° 20.24´W, 78–86 m, 27 August 2011, USNM 1547899 (= ULLZ 14614 ) . Northwestern Gulf of Mexico: 2 males, cw 5.6, 7.0 mm, off Louisiana , “The Halo” WW II shipwreck, 28° 42.01´N, 90° 08´W, 143 m, 14 August 2004, USNM 1547695 (= ULLZ 14505 ) ; 1 male, cw 4.8 mm, off Louisiana, Ewing Bank, 28° 05.011´N, 90° 58.646´W, 79–82 m, 5 December 2010, USNM 1547058 (= ULLZ 13237 ) ; 1 male, cw 4.8 mm, Ewing Bank , 28° 05.029´N, 90° 58.656´W, 78–83 m, 5 December 2010, USNM 1547060 (= ULLZ 13242 ) ; 1 male, cw 3.7 mm, 1 female, cw 4.0 mm, Fishnet Bank , TAMU submersible dive 74-G-10, 28° 09´N, 91° 49´W, 21 June 1974, USNM 1538101 (= ULLZ 12242 ) ; 1 male, cw 3.5 mm, West Flower Garden Banks, diver collection 48 m, 7 May 1972, USNM 1538099 (= ULLZ 12233 ) ; 1 male, cw 4.9 mm, off Louisiana, 28° 05.009´N, 91° 09.393´W, 109–110 m, 24 August 2008, USNM 1538097 (= ULLZ 11911 ) ; 1 male, cw 3.2 mm, Mysterious Bank, Texas, R / V Falkor ROV, 26° 46´N, 96° 42´W, 26 November 2012, USNM 1547880 (= ULLZ 14592 ); 1 male, cw 3.6 mm, 1 ovigerous female, cw 4.4 mm, Mysterious Bank, Texas, R / V Falkor ROV, 26° 46´N, 96° 42´W, 27 September 2012, USNM 1548935 (= ULLZ 15560 ); 2 males, cw 3.7, 2.3 mm, 3 females (2 ovigerous), cw 4.5, 4.8, 2.8, 4 unsexed tentatively identified juveniles, cw 1.6–1.9 mm, Aransas Bank, Texas, R / V Falkor ROV, 27° 36´N, 96° 27´W, 21 September 2012, USNM 1547711 (= ULLZ 14581 , photograph voucher); 3 males, cw 3.2, 3.5, 4.4 mm, 1 ovigerous female, cw 4.3 mm, Aransas Bank, Texas, R / V Falkor ROV, 27° 03´N, 96° 43´W, 21 September 2013, USNM 1547888 (= ULLZ 14602 ); 1 unsexed damaged, cw 3.4 mm, Dream Bank, Texas, R / V Falkor ROV, 27° 03´N, 96° 43´W, 23 September 2012, USNM 1547891 (= ULLZ 14605 ) .

Diagnosis. Carapace wider than long (length near 2/3 width), dorsal surface weakly convex, regions poorlydefined, granulate, size and density of granules increasing anteriorly in each region; frontal margin bilobed, median fissure distinct; anterolateral teeth arrayed in arc, first and second often fused, appearing as weakly spiniform lobes to nearly obsolete, third and fourth acute to subacute, third directed anteriorly to anteromedially, fourth directed anteriorly to anterolaterally, fifth at most a denticle or subacute process. Chelipeds densely granulate on superior and extensor surfaces, carpus superoflexor margin with two distinct acute to subacute processes, largest distal, apex directed dorsally. Pereopods two through five (walking legs) with merus superior margin bearing distinct row of small distally directed, triangular teeth, strongest distal. Male pleon anteriorly elongate, reaching beyond first pereopod condyle; second somite width subequal to that of first, seventh sternite obscured or at most visible as small sliver to either side; third segment proximo-lateral extremities broadly subtriangular, unevenly rounded, slightly overreaching fifth pereopod coxa proximally; third through fifth fused, sutures visible externally only as small notches laterally; sixth segment slightly broader than long; telson rounded. Male first pleopod (gonopod 1) long, sinuous, reaching beyond anterior end of median sternal groove, visible to either side of pleon distally, apex narrowly spatulate. Male second pleopod less than one-third length of first. Applicable GenBank sequence accession numbers for USNM 1543542 (= ULLZ 8170) and USNM 1577463 holotype (= ULLZ 8183, part) are as follow: (16s) EU863367 , EU863366 ; (12s) EU863301 , EU863300 .

Description. Carapace ( Fig. 1A ) weakly convex, distinctly wider than long, dorsal regions poorly-defined by shallow grooves, surface sparsely granulate, granules increasing in size and density anteriorly, most dense in hepatic and frontal regions, occasionally forming weak rows or carinae; frontal margin bilobed, downturned, slightly thickened by dense granules, median fissure distinct, lobes broadly convex, antennal sinus shallow, distinct; supraorbital margin granulate, median fissure small, indistinct, lateral fissure obsolete, or nearly so. Pterygostomial and subhepatic regions ( Fig. 1B ) granulate, granules small; pterygostomial ridge reduced, present as slightly raised line of granules. Branchiostegite below anterolateral teeth with ventral margin nearly straight above coxa of each walking leg, at most slightly cuspate. Second and third pleurites with full width narrowly visible below ventral margin of branchiostegite above pereopod coxae, anterolateral margin of fourth pleurite occasionally visible as small wedge- like prominence. Anterolateral teeth moderately developed, first and second teeth weak to obsolete, often reduced to spinous prominences; third and fourth teeth (appearing as second and third, respectively, given obsolescence to fusion of preceding and counting outer orbital angle as first) anterolaterally directed, typically ending in acute spiniform process distally, third largest; fifth tooth typically small, nearly obsolete, acute to subacute. Eyestalk with distinct raised, coarsely granulate anterior crest.

Third maxilliped ( Fig. 1 B–D) protopod subcuneate, narrowing laterally, bearing small subtriangular projection proximomesially, external surface with slight notch or groove near distomesial margin, patch of medium length simple setae distolaterally, continuing slightly onto epipod, distal surface deeply grooved to accept ventral edge of carapace, internal surface with two unequal projections on distal margin. Epipod strongly curved posteroventrally near one-third length, distally fringed with long simple setae; podobranch gill typically small, short, lamellae limited to tight terminal bundle (not shown). Endopod basis subtriangular, basis suture with ischium nearly fused, indistinct; ischium broadly subrectangular, proximal portion deflected laterally, external surface with few sparse granules near distomesial corner, mesial margin with irregular fringe of short to medium length simple setae, continued for short distance on internal surface, subtriangular uncalcified region at articulation with merus; merus subquadrate, lateral margin concave, distal margin with indentation mesially, distomesial corner excavated to accommodate carpus, external surface with several large coarse granules near distal and distomesial margins, internal surface deeply excavate to accept endopod of second maxilliped, excavation with fringe of short simple setae, internal surface with raised ridge of setae near mesial margin proximal to articulation with carpus, distomesial uncalcified region at articulation with carpus, mesial margin with sparse fringe of medium length simple setae; carpus appearing subcylindrical externally, subobovate internally, external surface granulate especially near extensor margin, internal surface with fringe of medium-long stout simple setae on distal margin; propodus cylindrical, internal surface with short row of medium-length stout simple setae near midlength; dactylus subcylindrical, tapering distally, nearly twice as long as propodus, flexor margin with short fringe of medium-length stout simple setae proximally, extending about half dactylus length, tip bearing dense tuft of long stout simple setae. Exopod sublanceolate, nearly linear, slightly tapering distally, internal surface mesial margin produced, forming subtriangular projection in distal third, projection fringed with several short to medium length simple setae, external surface mesial margin subtly crenulate, lateral margin with sparse fringe of very short simple setae in proximal one-half, internal surface with short irregular row of short to medium-length setae near mesial margin in proximal one-half; flagellum recurved, multi-articulate distally, bearing numerous long, simple setae.

Chelipeds (first pereopods) ( Fig. 1 E–G) moderately unequal, sparsely setose, dense broad field of subacute granules covering superior and extensor surfaces, occasionally forming one or more ridges on superior surface of carpus and propodus, especially on major chela; merus superolateral margins with large, broad, subacute, spines, flexor surface granulate, granules larger, sharper near superior and inferior margins, proximo-inferior margin typically fringed with short plumose setae, extensor surface densely granulate, granules decreasing in size and density from superior to inferior margins; carpus densely granulate with broad, subacute granules, strong distal subacute, spiniform, tooth on flexor side of superior surface, two smaller teeth proximally, superior and extensor surfaces with few sparse plumose setae, superodistal margin often with distinct fringe of plumose setae; propodus superior and supero-external surfaces densely granulate with few sparse simple setae, granules broad, subacute, superior surface occasionally with distinct longitudinal groove, flexor surface of palm smooth to micropunctate, distal margin near gape with fringe of small distinct teeth; fixed finger of major chelae short, stout, smooth on both flexor and extensor surface, extensor surface often with two shallow grooves, inferior margin weakly sinuous deflected gently downwards, apex distinctly curved upwards, opposable margin bearing two to three prominent teeth, often with several smaller teeth between, teeth occasionally worn to low rounded lobes; fixed finger of minor chela noticeably longer and more slender than that of major, opposable margin forming slender cutting edge, often with several small teeth proximally, occasionally worn to appear like two distinct platforms or steps; dactylus of major chela curved, slightly longer than fixed finger, superior surface with shallow, longitudinal groove on external side of superior midline, groove widest and deepest proximally, several medium length simple setae on proximal half, cutting edge armed proximally with two large subtriangular teeth, single triangular tooth near mid-length, and numerous small, variably rounded teeth along distal cutting edge, tip strongly curved downwards, forming coniform tooth; dactylus of minor chela curved, longer than fixed finger, superior ridge granulate, granules strongest proximally, shallow narrow groove on external side of superior midline, groove much deeper and broader than on the major chela, cutting edge dentition much weaker than in major chela, appearing as thin, weakly crenulate margin, tip strongly curved downwards to form sharp, coniform tooth.

.

Pereopods two through five (walking legs) generally similar in form ( Fig. 1H ), pereopods two through four subequal, fifth smallest; ischium extensor margin about one-half length of flexor margin; merus length slightly less than three times width at widest point, extensor margin bearing single longitudinal row of irregular acute teeth along with four or five long sparsely-plumose setae, excavate subdistally by smooth transverse depression or groove, disto-extensor margin curved upwards appearing as large distal subacute tooth, flexor margin granulate in proximal three-fourths with several simple setae, longest proximal; carpus strongly bent in flexor plane at near right angle, extensor margin densely granulate appearing as several irregular rows of subacute granules, creating elongate sulcus near extensor margin on posterior surface; propodus extensor margin granulate, granules subacute, with several plumose or simple setae, granules continued onto posterior surface above midline, flexor margin with irregular fringe of mixed short stout setae and long thin setae; dactylar-propodal locking mechanism not developed; dactylus subcylindrial, tapering distally, flexor and extensor margins with short dense pubescence intermixed with long simple setae, corneous tip falciform, lacking subterminal, calcareous, raptorial tooth.

Thoracic sternum of male ( Fig. 1 J–K) narrow, anteriorly projected, length from apex to suture of fourth and fifth sternites (measured at the edge of the pleon) 0.57–0.61 times greatest width of fourth sternite (including episternites); pleonal depression of fourth sternite shallowly concave near midline, just anterior to median sternal groove; fourth through sixth episternites acutely angled posteriorly; seventh episternite broad, round; eighth sternite not visible between lateral margin of flexed second pleonal somite and fifth pereopod condyle; press-button just posterior to suture of third to fourth sternite.

Pleon of male ( Fig. 1 I–K) with third through fifth somites fused; first somite lateral margins rounded, widest at articulation with carapace, narrowest at articulation with second somite; second somite narrowest proximally, widest distally near articulation with somite three; third somite widest at lateral flange; fused third through fifth somites narrowing distally, width at articulation with sixth somite half or less that at articulation with second somite, sutures between fused somites evident only as slight indentations on lateral margins; sixth somite lateral margins nearly parallel at most slightly convex proximally, swelling slightly near articulation with telson to accept press-button in- ternally; telson terminally rounded, widest near mid-length, distolateral margins slightly excavate to accommodate first gonopod. Pleon of female with first somite narrowing distally, widest at articulation with carapace, second somite with margins nearly parallel, slightly expanded distally; fourth somite widest, lateral margins rounded; fourth through sixth somites each tapering to articulation with the next, narrowest point at the articulation between sixth somite and telson; telson subtriangularly rounded.

Male first gonopod (first pleopod) ( Fig. 1L ) long, sinuous, reaching beyond sternal groove, tips exposed to either side of telson when abdomen flexed in mature; terminal apparatus superficially simple, appearing spatulate with sub-apical microspinulous spines. Male second gonopod (second pleopod) ( Fig. 1M ) less than one-third length of first gonopod. Female mature gonopore broadly rounded medially, occupying more than half of anterior to posterior transverse width of sixth sternite, largely filled by rounded operculum attached laterally along slightly raised elongate lip, narrow opening to medial side strongly crescentic.

Color. Primarily orange to dark orange or reddish brown patterned over whitish to very light orange background, carapace dorsally with broad intricately margined band of orange arched anteriorly from each branchial region, broadest and usually darkest medially where joined over gastric region, arch forming pattern like front of crown or tiara, usually with somewhat lighter medial extension posteriorly to cardiac region, bifurcated from intestinal region to posterior margin of carapace ( Fig. 2 A–D). Chelipeds dorsally orange, often darkest on ridges and tubercles, palms with light whitish bands distally, as well as on inner and ventral surfaces, fingers light to dark brown. Walking leg articles with broken bands of orange on whitish background, bands most obvious as orange patches on superior surfaces, usually with three such patches on meri, most proximal of which is smallest and often very diffuse to obsolete. Eggs on ovigerous females reddish magenta.

Habitat. Abundant on offshore reefs and banks, especially in small cavities and interstices of eroded hard substrates as well as among sponges, bryozoans, corals, encrusting algae, and other epibiota of fouling communities. Confirmed depth records range from 58–143 m; some additional collections are from within sponges taken at depths estimated to be 200–300 m (Aransas Bank, TX).

Size. The carapace ranges to a maximum of cw 7.0 mm, determined for the largest male among available collections. Juveniles of neither sex were definitively identifiable at less than cw 2.0 mm, though collections included some specimens of cw 1.6 mm that appear to represent the species. The smallest examined ovigerous female was cw 3.9 mm.

Distribution. Middle to outer continental shelf waters of the northeastern to northwestern Gulf of Mexico.

Etymology. The name “tiara” alludes to the reddish pattern that typically spans the dorsal carapace, the shape of which suggests the elevated front of a tiara or crown.

Remarks. While it is at first glance easy to mistake fresh specimens of Guinope tiara n. gen, n. sp. for Garthiope barbadensis , the distinctive dorsal color pattern on the carapace in both sexes and the occurrence of ovigerous females at rather small sizes bearing clutches of bright reddish magenta eggs usually facilitate recognition, even before microscopic examination of the very diagnostic first gonopods. Among small regional xanthoid crabs, a similar dorsal color pattern is found only in some specimens of Scopolius nuttingii ( Rathbun, 1898) , though it is in that case usually less ornately defined.

Lacking knowledge of gene sequences, live coloration, or fine sculpture of mature male first gonopods, identification of Guinope tiara n. gen., n. sp. can be based upon other features in morphology, even though some characters for separations are difficult to quantify. Among other small, regionally distributed xanthoids that occur sympatrically with Guinope tiara n. gen., n. sp., the only (albeit provisionally assigned) confamilial) Melybia thalamita might be expected to resemble G. tiara n. gen., n. sp., but it is instead among the least likely to be confused with it. Melybia thalamita is immediately separated by its having the merus of pereopod 2 and 3 armed by a unique ventrodistally directed spine on the distal ¼ of the inferior margin, by the third maxilliped merus bearing a uniquely produced lobe on its anterolateral corner, and by strong differences in the carapacial outline ( Rathbun 1930; Williams 1984; Mendoza et al. 2012). Melybia also has a relatively broader fronto-orbital margin, relatively longer posterolateral margin, and much stronger development of its two largest anterolateral teeth into elongate hooked spines than in Guinope n. gen. In addition, the chelipeds in Melybia differ from those of Guinope n. gen. in being far more elongate and more heavily armed by elongate spines, with a much more elongate palm that itself bears a distinct row of enlarged spines along its superior margin, and otherwise has uniquely elongate spines arming the anterior (superoflexor) margin of the merus and inner (supero-internal) corner of the carpus. This markedly differs from the chelipeds in Guinope n. gen., which are much more typical of those in panopeid crabs.

Guinope tiara n. gen., n. sp. can in turn be distinguished from Glyptoplax smithii , Milnepanopeus lobipes (A. Milne-Edwards, 1880) , Panoplax depressa Stimpson, 1871 , and Scopolius nuttingii , and? Micropanope pusilla A. Milne-Edwards, 1880 (the latter a questionable generic assignment) by its having superior margins on the meri of the walking legs armed by a defined row of well separated short but erect, distally directed, sometimes weakly hooked, spinules (as is also the case in Batodaeus , Garthiope , the remaining species of Micropanope , and Nanoplax ), instead of having margins that are weakly tuberculate, smooth, granulate, or microdenticulate (see Rathbun 1930; Guinot 1967, 1990; Williams 1984; Lemaitre 1984; Vázquez-Bader & Gracia, 2004, Thoma & Felder 2012). Guinope tiara n. gen., n. sp. can be separated from all the remaining, other than Micropanope lobifrons A. Milne- Edwards, 1880 and Micropanope sculptipes Stimpson, 1871 , by having the posteriomost anterolateral tooth of the carapace obsolescent, its being evident as a dimunitive blunt angle, tubercle, spinule, or acute granule. The anterolateral margin thus appears to have either 3 or 4 anterolateral teeth (counting the orbital angle), and 4 only if the second tooth remains distinguishable (countable) as at least a small denticle or tubercle. The others, including Batodaeus urinator , Garthiope barbadensis , G. spinipes , Micropanope truncatifrons ( Rathbun, 1898) , Milnepanopeus lobipes , Nanoplax xanthiformis (A. Milne-Edwards, 1880) , and Panoplax depressa , all have the positional fifth anterolateral tooth of the carapace small but more strongly developed than in Guinope tiara n. gen., n. sp., its sometimes being dentiform or spine-tipped. The margin thus overall appears to have 4 or 5 well-developed anterolateral teeth counting the outer orbital angle, 4 only if the second is indistinguishably fused into a broad lobe with the first or if the positional second tooth is replaced by development of several short spines. Among these, only Garthiope barbadensis and G. spinipes have their anterolateral teeth arranged in an arc relatively similar to those in Guinope tiara n. gen, n. sp., whereby the rounded anterolateral margins conform closely to the ovoid outlines of the broad carapace.

Given the challenges of its morphological distinction, and thus suspecting that this relatively common new species could have been previously misreported as Garthiope barbadensis , we reviewed the scant regional reports of the latter species in the course of building our synonymy. At one point, we envisioned our synonymy for Guinope tiara n. sp. should include references to specimens reported as Micropanope barbadensis s.l. in studies of larval life history by Gore et al. (1981: 28–50, tab.1, figs 1–9) and in ecological studies by Reed et al. (1982: 761–786, tab. 2, fig. 7). In both cases, the specimens originated from deep (80 m) habitats on Occulina banks accessed off the Atlantic coast of Florida by submarine lock-out divers, with the species being found only at the deepest of several sampled sites. Prior to first-hand study of specimens reported from that site, the record was included in the distribution that Felder et al. (2009: 1084) reported for Garthiope barbadensis .

Vouchers identified as Micropanope barbadensis during the aforementioned Occulina bank studies were located and examined at the Harbor Branch Oceanographic Institution (HBOI) collection, an administrative unit of Florida Atlantic University’s Fort Pierce campus. Without question, they do not represent Garthiope barbadensis , but instead conform closely to our morphological diagnosis for Guinope n. gen., including carapacial dentition, the male pleon, and the first gonopods. So nearly as can be determined, this includes the parental females collected alongside archived males and used in the Gore et al. (1981) larval study (parental females being found in the HBOI collections, and not the USNM as reported); thus, those larval stage descriptions can no longer be regarded to represent Garthiope but rather Guinope n. gen. However, as these Atlantic specimens are of somewhat larger size and appear to have relatively broader carapaces than do specimens of the type series from the Gulf of Mexico, we cannot state with certainty whether they represent variants of Guinope tiara n. gen., n. sp. or instead a second species of this new genus. We defer that decision pending comparative gene-sequence analyses and detailed morphological study of materials from Florida Occulina bank habitats.

Figures

FIGURE 1. Guinope tiara n. gen., n. sp. A–F, H, J, L, M = male holotype, cw 4.2 mm, northern Gulf of Mexico, Sackett Bank, Louisiana, 28° 37.81´ N, 89° 33.32´ W, 63–65 m, 28 June 2006, USNM 1577463 (= ULLZ 8183, part); G, I, K = male paratype, cw 5.2 mm, northern Gulf of Mexico, 120 km south of Mississippi-Alabama state border, 29° 15.68’ N, 88° 20.24’ W, 78–86 m, 27 August 2011, USNM 1547899 (= ULLZ 14614): A, carapace, left half only; B, buccal region; C, left third maxilliped, external surface; D, left third maxilliped, internal surface, E, right (major) chela, extensor surface; F, right (major) cheliped, superior surface; G, left (minor) chela, extensor surface; H, right second pereopod, anterior surface; I, pleon, external surface; J, posterior sternum overlain by flexed pleon, postero-ventral surface; K, anterior sternum overlain by flexed pleon, ventral surface; L, right first gonopod, pleonal-mesial surface; M, right second gonopod, lateral surface. Scale bars A, B, E–I = 2.0 mm; C, D, J, L, M = 1.0 mm; K = 0.4 mm.

FIGURE. 2. Guinope tiara n. gen., n. sp., color variants, northern Gulf of Mexico: A, female, cw 5.8 mm (USNM 1543849 = ULLZ 8173); B, male, cw 6.9 mm, USNM 1543895 (= ULLZ 8581); C, male, cw 3.7 mm, USNM 1543849 (= ULLZ 8173); D, ovigerous female, cw 4.5 mm, Sackett Bank, Louisiana, USNM 1547740 (= ULLZ 14552)