Naushonia portoricensis ( Rathbun, 1901 )

Komai, Tomoyuki & Anker, Arthur, 2015, Additional records of the laomediid mud-shrimp genus Naushonia Kingsley, 1897 (Crustacea: Decapoda: Gebiidea), with a revised identification key, Zootaxa 3974 (3), pp. 341-360 : 348-354

Naushonia portoricensis ( Rathbun, 1901)

Figs. 3–6

Homariscus portoricensis Rathbun 1901: 98 , fig. 19 (type locality: Playa de Ponce, Puerto Rico).

Naushonia portoricensis: Chace 1939: 524 –530, figs. 1–14 (Havana, Cuba).— Gurney & Lebour 1939: 610, figs. 1–14 ( Bermuda, larvae).— Goy & Provenzano 1979: 352 –357, figs. 6B, 7B, 8B (Playa de Ponce, Puerto Rico; Quintana Roo, Mexico).— Martin & Abele 1982: 482 (key).— Dworschak et al. 2006: 2 (Boca Chica, Dominican Republic).—Perez- Gelabert 2008: 36 (list).— Komai & Anker 2010: 45 (key).— Anker 2014: 758 (Table II), 760 (key).

Material examined. French Antilles: 1 female (pocl 3.5 mm), St. Martin, Pinel Island, sta. STM-060, 18°10.3’N, 63°01.6’W, 1.5–7.5 m, reef, under rocks, coll. A. Anker, 24 April 2012, BSTM-1708, FLMNH UF Crustacea 32500.

Description. Body ( Fig. 3 A–D) moderately robust, not particularly broadened or slender. Rostrum ( Figs. 3 A, 4A) strongly flattened dorsoventrally, broadly triangular in dorsal view (approximately as long as basal width), terminating in subacute apex, slightly overreaching distal margin of second article of antennular peduncle; lateral margins feebly convex, minutely denticulate, without conspicuous spines; dorsal surface shallowly concave.

Carapace ( Figs. 3 A, B, E, 4A) subcylindrical, with distinct linea thalassinica extending almost over entire length; surface glabrous except for sparse short setae on dorsal surface. Postorbital spine simple, acuminate, with smooth mesial margin. Anterolateral margin deeply notched just ventral to small branchiostegal spine, margin superior to branchiostegal spine unarmed; pterygostomial angle extending as far as branchiostegal spine, acutely pointed. Gastric region with five low longitudinal carinae, median part flanked by submedian carinae forming plateau-like elevation; mid-dorsal carina, interrupted by cervical groove, extending from anterior 0.2 of carapace length to posterodorsal margin, minutely granulate; submedian carinae diverging posteriorly and minutely granulate in anterior 0.8 of carapace, curved mesially and becoming blunter at posterior 0.2 of carapace, reaching to cervical groove; lateral carinae minutely spinulose, diverging posteriorly, gradually blunter, non-spinulose posteriorly, continuous to posterior border of cervical groove. Cervical groove conspicuous, shallow, crossing slightly posterior to mid-length of carapace, continuous with depressions delimiting posterior part of gastric median plateau.

Pleon ( Fig. 3 C, D) smooth. First pleomere with tergum divided in two sections by shallow transverse groove, posterior section with low, short mid-dorsal carina and faint transverse carina extending to junction between tergum and pleuron; pleuron rounded posteroventrally and obtusely angled on anterior margin, without conspicuous knob-like elevation at articulation to second pleomere. Second pleuron marginally unarmed, with posterior lobe less expanded than anterior lobe; third to fifth pleura rounded, subrectangular in general outline, marginally unarmed. Sixth pleomere not particularly widened posteriorly, without conspicuous tubercles or other armature on surface; tergum with W-shaped area marking uncalcified integument; posteroventral angle rounded; posterolateral process rounded.

Telson ( Fig. 3 F) about 1.3 times longer than wide, rounded posteriorly; dorsal surface slightly elevated medially in anterior part, with many spinules or minute tubercles on either side of midline; lateral margins each with 1 minute tooth located at posterior 0.4, gradually converging into rounded posterior margin fringed with long plumose setae.

Eyestalks ( Figs. 3 E, 4A) short, each with small tubercle at distomesial angle; cornea darkly pigmented, visible in dorsal view.

Antennular peduncle ( Figs. 3 E, 4A) slightly falling short of distal margin of fifth segment of antennal peduncle. First segment not visible in dorsal view, nearly as long as distal 2 segments combined; dorsal surface with statolith opening closed by stiff setae, distodorsal margin strongly raised; ventral surface with distinct median ridge in proximal half and small distomesial spine. Second and third segments unarmed, latter fairly flattened dorsoventrally. Lateral flagellum longer than peduncle, composed of 13 (left) or 14 (right) articles; mesial flagellum about 0.7 length of lateral flagellum, composed of about 8 articles.

Antennal peduncle ( Figs. 3 E, 4A–C) stout. First segment with few minute denticles laterally on distoventral margin. Second segment with 1 strong distodorsal spine laterally, distolateral margin otherwise unarmed. Third segment with 1 minute subdistal spine on ventromesial margin. Fourth and fifth segments each with very small distolateral spine; fifth segment slightly wider than long. Antennal scale moderately broad, short, almost reaching distal margin of fifth segment, terminating in strong, mesially curved spine; lateral margin slightly convex, armed with 4 small spines (except for terminal spine) in distal 0.7 of its length, spines increasing in size distally; mesial margin strongly convex, with row of stiff setae; dorsal surface with low longitudinal carina. Antennal flagellum slightly shorter than body; articles with numerous short and long setae on distal margins.

Epistomial horn moderately slender, overreaching mid-length of first article of antennular peduncle.

Mouthparts not removed. Third maxilliped ( Fig. 5 A–C) with moderately slender endopod composed of five articles. Coxa with setobranch composed of several long setae arising from small tubercle located near base of epipod; distoventral margin unarmed. Basis short, with 1 spinule on ventromesial margin. Ischium flattened dorsoventrally, slightly widened distally, distodorsal angle slightly produced; ventrolateral margin carinate, spinulose; distomesial angle strongly produced; crista dentata well developed, with row of narrowly spaced, slender spinules. Merus shorter than ischium, with 1 small distodorsal spine; lateral surface with few spinules adjacent to dorsal margin; ventral margin spinulose, with conspicuous distal spine. Carpus short, cup-shaped. Propodus slightly longer than dactylus. Dactylus slightly curved, tapering to blunt tip, with thick cluster of stiff setae along flexor surface to tip. Exopod slender, overreaching distal margin of ischium; flagellum multiarticulated. Epipod large, tapering distally, margins spinulose (spinules on dorsal margin much larger than those on ventral margin); mastigobranch subrectangular with truncate distal margin, narrowing basally; podobranch consisting of numerous, slender lamella.

First pereopods (= chelipeds) ( Fig. 4 D–F) strong, subchelate, equal in size, symmetrical in shape, strongly flattened dorsoventrally. Ischium widened distally; narrow mesial surface flanked by clearly delimited, microscopically spinulose, dorsomesial and ventromesial margins; lateral margin carinate, microscopically spinulose. Merus widened distally, cross-section subtriangular; dorsal surface almost smooth; distomesial angle produced as trispinose lobe; lateral margin distinctly carinate, microscopically spinulose (spinules increasing in size distally), terminating in minute spine; mesial face narrow, flanked by sharply delimited, microscopically spinulose dorsomesial and ventromesial margins, latter continuing to distomesial lobe; ventral surface elevated along midline, ventromesial face nearly smooth. Carpus short, slightly widened distally; surfaces smooth; distodorsal margin smooth; dorsolateral margin distinctly carinate, microscopically granulate; mesial margin distinctly carinate; ventral surface distinctly carinate along midline, distoventral margin smooth. Palm elongate, subovate in general outline, rhomboidal in cross-section, about 1.6 times as long as wide, subequal in length to ischium and merus combined; dorsal surface faintly elevated along midline, with numerous, scattered, short setae, otherwise smooth; lateral margin carinate, microscopically spinulose except for some distal spinules, with row of sparse short to long setae; mesial margin (proximal to fixed finger) diverging against lateral margin, sharply carinate, microscopically spinulose, with row of long setae; ventral surface weakly elevated along midline, with scattered low granules, latter particularly numerous lateral to midline; pollex triangular, relatively strong, arising at mid-length of palm; occlusal margin strongly oblique, its distal 0.4 with row of 4 sharp teeth decreasing in size distally, proximal-most tooth prominent, much stronger than others, broader than fixed finger, proximal 0.6 without conspicuous armature, with row of stiff setae. Dactylus moderately slender, gently curved, closing completely against cutting edge, tip overlapping dorsal side of palm when closed; extensor margin with double row of long setae, proximal part not particularly expanded; flexor (occlusal) margin sharply edged.

Second pereopod ( Fig. 5 D, E) moderately stout, simple. Merus with sparse row of elongate setae on ventral margin. Carpus about 0.4 times as long as merus. Propodus longer than wide, subequal in length to carpus. Dactylus feebly curved, terminating in small, acute unguis; dorsal surface with dense setae forming brush-like structure; ventral margin minutely pectinate in distal half.

Third to fifth pereopods moderately slender, decreasing in length posteriorly. Third pereopod ( Fig. 5 F, G) with ischium, merus and carpus unarmed, with sparse short setae on dorsal and ventral margins; merus about 5 times longer than wide; carpus about half-length of propodus; propodus with row of short stiff setae on ventral margin; dactylus about 0.6 times as long propodus, terminating in slender, basally demarcated unguis, lateral surface with row of 4 small movable spines adjacent to dorsal margin, ventral margin forming thin lamella with slender comblike spinules, few spinules proximal to mid-length longer than others, tip of spinules blunt. Fourth pereopod ( Fig.

5H, I) similar to third, as illustrated; dactylus with 6 movable spines on lateral surface adjacent to dorsal margin. Fifth pereopod ( Fig. 5 J, K) with grooming setae on distal part of propodus; dactylus unarmed on lateral surface, ventral lamina poorly developed.

Gill formula as summarized in Table 1; single arthrobranch on first maxilliped small but distinctly lamellate; epipods on first to third pereopod marginally spinulose, each with sickle-shaped mastigobranch and multi-lamellate podobranch; epipod on fourth pereopod tapering distally to rod-like prolongation; podobranch greatly reduced to rudimentary bud; mastigobranch also reduced to tiny bud-like process; setobranchs present on third maxilliped to fourth pereopod.

First pleopod uniramous; articulation between protopod and ramus obsolete. Second to fifth pleopods biramous, rami slender, slightly unequal, exopods longer than endopods, latter without appendices internae.

Uropod ( Fig. 4 G) overreaching posterior margin of telson. Protopod bilobed, with deep V-shaped notch, posterior margin microscopically spinulose. Endopod and exopod subovate, each with minutely spinulose transverse suture. Exopod with low mid-dorsal ridge bearing some spinules; lateral margin faintly sinuous, serrated with 4 spinules and 1 posterolateral movable spinule. Endopod with low mid-dorsal ridge bearing some minute spinules; lateral margin nearly straight, with small posterolateral spine.

Colouration in life. Body and appendages whitish; reddish ovary visible through integument ( Fig. 6 ).

Distribution. Western Atlantic: Puerto Rico (Ponce), Dominican Republic (Boca Chica), Cuba (Havana), Mexico (Quintana Roo) ( Rathbun 1901; Chace 1939; Goy & Provenzano 1979; Dworschak et al. 2006), French Antilles ( St. Martin) (present study), possibly also in Bermuda (larval material of Gurney & Lebour 1939).

Habitat. Intertidal and shallow subtidal; on sand or mixed sand-rubble bottoms, under large rocks and coral rubble.

Remarks. Naushonia portoricensis was originally described on the basis of a single incomplete female specimen, without pereopods, collected at Playa de Ponce, Puerto Rico ( Rathbun 1901; as Homariscus portoricensis , Homaridae ). Chace (1939) reported a complete female of N. portoricensis from Havana, Cuba, providing a rather superficial description and some illustrations. Gurney & Lebour (1939) identified larvae from plankton samples taken off Bermuda as N. portoricensis ; however, this record requires confirmation. Goy & Provenzano (1979) examined the female holotype and two additional male specimens from Quintana Roo, Mexico, and provided comparative remarks and illustrations of selected body parts to show some diagnostic characters. Most recently, Dworschak et al. (2006) listed, under comparative material, a female specimen from Boca Chica, Dominican Republic.

The present specimen from St. Martin generally agrees with the original description of N. portoricensis in Rathbun (1091) and taxonomic accounts in Chace (1939) and Goy & Provenzano (1979). As mentioned above, however, the illustration of the carapace in Goy & Provenzano (1979: fig. 6B) is not accurate in depicting bifid postorbital spines, which, as we concluded above, do not exist in Naushonia .

Morphologically, N. portoricensis is most similar to N. crangonoides , N. japonica , N. latimana , N. macginitiei , N. perrieri , and N. serratipalma , being distinguishable from all of them by a strongly incurved terminal tooth of the antennal scaphocerite ( Fig. 4 B) and the plateau-like elevation on the gastric region of the carapace, flanked by two submedian carinae and posteriorly defined by conspicuous depressions continuing to the cervical groove ( Figs. 3 A, B, 4A).

Figures

FIGURE 3. Naushonia portoricensis (Rathbun, 1901), female (pocl 3.5 mm) from St. Martin, French Antilles, FLMNH UF Crustacea 32500. A, carapace, dorsal view; B, same, lateral view; C, pleon, dorsal view; D, pleon, telson and left uropod, lateral view; E, anterior part of carapace and left cephalic appendages, lateral view; F, telson, dorsal view. Scale bars: 1 mm for A – D; 0.5 mm for E, F.

FIGURE 4. Naushonia portoricensis (Rathbun, 1901), female (pocl 3.5 mm) from St. Martin, French Antilles, FLMNH UF Crustacea 32500. A, anterior part of carapace and cephalic appendages, dorsal view; B, left antennal scale, dorsal view (setae omitted); C, left antennal peduncle, ventral view (setae omitted); D, left cheliped, dorsal view; E, same, ischium and merus, ventral view; F, same, carpus and chela, ventral view (only ventral setae shown); G, right uropod, dorsal (perpendicular) view. Scale bars: 0.5 mm.

FIGURE 5. Naushonia portoricensis (Rathbun, 1901), female (pocl 3.5 mm) from St. Martin, French Antilles, FLMNH UF Crustacea 32500, left thoracic appendages. A, third maxilliped, lateral view; B, same, ischium, dorsal view; C, same, exopod, dorsal view; D, second pereopod, lateral view; E, same, dactylus, mesial view; F, third pereopod, lateral view; G, same, dactylus, lateral view; H, fourth pereopod, lateral view; I, same, dactylus, lateral view; J, fifth pereopod, lateral view; K, same, propodus and dactylus, lateral view. Scale bars: 0.5 mm.

FIGURE 6. Naushonia portoricensis (Rathbun, 1901), female (pocl 3.5 mm) from St. Martin, French Antilles, FLMNH UF Crustacea 32500, living individual in dorsal and lateral views.