Synapseudes hansknechti Drumm, 2018

Heard, Richard W., Stępień, Anna, Drumm, David T., Błażewicz, Magdalena & Anderson, Gary, 2018, Systematic and taxonomic observations on the subfamily Synapseudinae Guţu, 1972 and related metapseudid taxa (Crustacea: Tanaidacea: Apseudomorpha), with the erection of a new genus and descriptions of three new species, Zootaxa 4370 (4), pp. 301-344 : 332-339

Synapseudes hansknechti Drumm & Heard, n. sp.

Figures 16–19

Synonymy. Synapseudes sp. A Heard et al., 2004: 53, 65 (nec Synapseudes sp. A. Suárez-Morales et. al. 2004, and García- Madrigal et. al. 2005).

Material examined. Holotype— ovigerous female, USNM 1422301, 26 09.792’ N, 80 05.429’ W, hard-bottom with Acropora cervicornis beds, Ft. Lauderdale, Florida, depth 1 to 3 m, coll. Judy Robinson.

Paratypes (same collection data as for holotype) — one subterminal ♂, two ♀ (one incubatory, one with oöstegite buds), USNM 1422302 ; three subadult males, three females (one incubatory, two pre-incubatory), one juvenile , GRCL 6585.

Additional (non-type) material —two adult ♂, one ♀ with oöstegites two juveniles, and six mancae, 325'29″N, 7935'45″W, off Edisto Island, South Carolina, calcium carbonate hard bottom, depth 38 m, coll. R/V Nancy Foster, Apr 29, 2005.

Diagnosis. Rostrum with distal margin having deep notch, appearing bilobed; epistome armed with row of subacute spines and well-developed acute spine. Antennule with peduncle article-1 large, slightly more than twice as long as wide; inner margin bearing row of about ten irregularly shaped blunt teeth or tubercles, usually two most proximal ones distinctly larger than others. Antenna with peduncle having four functional articles, but with article- 4 appearing partially biarticulate, flagellum apparently composed of single article terminating in single long simple seta and two minute subdistal accessory setae. Chela in both sexes symmetrical with distinct tuberculate teeth. Cheliped of male distinctly larger than that of female. Female and male chela with three simple setae on lateral face at articulation with fixed finger and dactylus. Pereopods 1–3 having basis with dorsal margin usually bearing two or more large blunt spiniform apophyses; propodus having ventral margins with four stout spiniform seta decreasing in size proximally. Pleonites 1–3 completely delineated and having distinct lateral processes terminating in blunt spine. Uropod with endopod composed of four articles. Pigment on peduncular article-3 of antennule, on surface of carapace, and on dorsal surface of pereonite-4.

Description of adult female with oöstegites. Body ( Fig. 16A–C ). Total length of adults 1.5 to 2.1 mm, body sub-cylindrical, dorsal surface granular.

Cephalothorax ( Fig. 16A ). Length about 1.2 times that of width at posterior margin. Carapace pigmented and granulated (not illustrated). Ocular lobes rounded. Eyes present, with pigment and visual elements. Rostrum bilobed, with margins granulate. Mid-lateral dorsal surface of carapace with two pairs of simple setae.

Epistome. With well-developed anteriorly directed spine.

Pereonites ( Fig. 16A ). Wider than long, gradually decreasing in width posteriorly, combined length of first two slightly less than that of cephalothorax. Pereonite-4 with pigment dorsally. All with one pair of anterolateral and anterodorsal setae and granulated on dorsal surface (not illustrated).

Pleon ( Fig. 16A, G ). Granular dorsally and laterally; three distinct pleonites delineated by sutures, all with ventrolateral extensions armed apically with blunt translucent spine; pleonite-1 twice combined length of pleonites 1–2. Pleonite-1 with two pairs of mid-lateral, and one pair of dorsal, setae. Pleonite-2 with short pair of dorsolateral setae. Pleonite-3 pleonite lacking dorsal and lateral setae.

Pleotelson ( Fig. 16A, G ). Short, compressed, formed by fusing of telson and last three pleonites, constricted posteriorly forming upturned, pointed terminus bearing pair of small medial subapical setae. Anterolateral margins bearing stiff setae, anterior most small and proximal most long robust, strongly-developed; dorsal surface granular with four long, robust setae.

Antennule ( Figs 16D–F ; 19A–D). Peduncle with four articles, often appearing geniculate. Article-1 large, slightly more than twice as long as wide; inner margin with row of more than ten irregularly shaped blunt teeth or tubercles, usually two most proximal distinctly larger than others; outer margin with two or three proximal broom setae, several setae on dorsal surface. Article-2 pigmented, less than half length of article-1, with four subdistal broom setae and one long simple seta on outer margin, outer distal margin produced in a stout blunt spine. Article- 3 much narrower and about half length of article-2, inner distal corner with two simple setae and one small seta on outer distal corner. Article-4 about half length of article-3, with notch for insertion of outer flagellum, one distal broom seta and one distal simple seta on dorsal surface. Flagella subequal; outer flagellum with three articles bearing simple setae (including four long terminal setae) and two aesthetascs (one each on inner distal corners of articles 1 and 2); inner flagellum having two articles, article-1 almost twice as long as distal article-2 with one simple seta on inner distal margin, article-2 with proximal broom seta and two distal simple setae.

Antenna ( Fig. 16H, I ). With five functional articles, four peduncular and one flagellar; length, excluding long terminal seta, shorter than article-1 of antennular peduncle. Peduncle article-1 strongly developed, nearly as wide as long, with course granulate lateral margins bearing small stout curved spines distally. Article-2 about half length and width of article-1, with four or five short spines along lateral margin and small, stiff, simple seta on distolateral margin. Article-3 shorter and narrower than article-2, crenulate, with one small curved spine on inner distal corner, distal margin tuberculate. Article-4 longest, but possibly representing vestiges of two articles (see arrows Fig. 16H, I ). Flagellum minute, und, cap-like, with long terminal simple seta and two minute simple subterminal accessory setae.

Mandibles ( Fig. 17A, B ). Left mandible with weakly-dentate incisor process; lacinia mobilis palmate with four rounded denticles; setiferous lobe with three setulate setae; molar process forming acute tip along lower margin. Right mandible having bidentate incisor process; lacinia mobilis bidentate; setiferous lobe with five setulate setae; molar process blunt, with three or four small distal setae. Palp with three articles, articles 1 and 2 asetose, subequal in length; article-3 short, length less than one third that of article-2, with two strongly-developed, finely-pectinate, setae (one longer than the other).

Labium ( Fig. 17E ). Palp with distal half of outer margin setose, one terminal spiniform seta, inner margin lacking setae; basal lobes with row of fine hirsute setae.

Maxillule ( Fig. 17C ). Outer endite with apparently eight terminal spiniform setae, hirsute setae on outer margin; inner endite bearing four distally setulose setae, hair-like setae on outer margin; palp biarticulate with two long terminal setulate setae.

Maxilla ( Fig. 17D ). Moveable endite having outer lobe with outer margin bearing row fine setae, distal margin with six well-developed, long simple setae; inner lobe with five simple setae (inner seta with proximal setules). Fixed endite: outer lobe with six or seven distal setae (three or four finely setulate), two spiniform, and one stout setulate seta appearing bidentate, and one subdistal simple seta ventrally. Inner lobe with row of about nine or ten basally swollen, distally setulate setae, one subdistal long pectinate seta medially.

Maxilliped ( Fig. 17F ). Coxa small, subrectangular, over twice as long as wide. Basis subquadrate, asetose. Endite with two coupling hooks (retinacula) sometimes secondarily fused ( Fig. 17G ), four or five basally swollen, distally setulate setae along medial margin; distal margin (right to left) with four distal spiniform setae curving and decreasing in size medially, two or three small, short, setulate setae, long simple seta on inner distal margin. Palp article-1 with narrow distolateral elongation bearing large buttressed, spiniform seta extending distolaterally just past proximal margin of article-2, one short simple setae on mediodistal inner corner. Article-2; distolateral margin weakly lobate with long, strongly-developed seta (longer, but less robust than one on distolateral margin of article- 1); row of proximally curved and directed spiniform setae along the inner ventral margin; three or four basally swollen setae, two simple, one near inner distal margin and one long proximal one extending to the distal third of article-3. Article-3 with inner margin having four basally swollen setae, several lateral simple setae; one simple distal seta and strongly developed pectinate seta. Article-4 with two pectinate setae, four basally swollen setae and long simple terminal seta.

Epignath ( Fig.17H ). Basally inflated, tapering, margin with fine hair-like setae, terminal seta large, length slightly shorter than main body of epignath.

Cheliped ( Fig. 17I, J ). Basis inflated, suboval in lateral view, crenulated mid-ventrally, with small seta on mid and distoventral margin. Merus appearing V shaped in lateral view, extending ventrally approximately half length of carpal margin, with two simple marginal or sub-marginal setae. Carpus expanded distally, slightly more than twice as long as broad, with two subdistal simple setae and distal small tubercle; subdistal simple seta on dorsal margin. Propodus with inner face of palm having two short bipectinate setae on inner distal face and three simple setae on outer distal face adjacent to articulation with dactylus (movable finger); fixed finger with four submarginal simple setae on outer face of distal third of fixed finger; two marginal and two submarginal setae on inner face and proximal to sclerotized orange-brown unguis; cutting edge crenulate proximally. Dactylus over two thirds length of palm, with cluster of three simple short setae near cutting edge on inner face and just proximal to well-developed orange-brown unguis.

Pereopods ( Fig. 18A–J ). Ambulatory with pereopods 1–3 directed anteriorly; pereopod-4 flexible, capable of both anterior and posterior orientation; pereopods 5–6 directed posteriorly. Basis on pereopods 1–6 with subdorsal margin bearing two sensory setae on proximal third of article (often broken off and appearing missing). Propodus on pereopods 1–6 with dorsal margin having broom (sensory) seta. Dactylus on all pereopods somewhat similar to each other, but those on the last three pairs are more robust. All pereopods having dactylus with minute seta on ventral and dorsal mid-margins, small tubercle with associated minute seta ventrally just proximal to unguis.

Pereopod-1 ( Figs 18A, B ; 19C). Basis longer than ischium, merus, and carpus combined; dorsal margin armed with two to four blunt or spine-like apophyses, two small simple setae on dorsal margin and three small simple setae on ventral margin. Ischium with two simple setae, one very small on distoventral corner. Merus with distodorsal acuminate spiniform seta, and subdistal short spiniform seta on ventral margin, two subdistal short simple setae and two simple setae on ventral margin. Carpus slightly less than half length of merus, subquadrate, about as broad as long, distoventral margin with two spiniform setae, two subdistal spiniform setae, and one distodorsal acuminate spiniform seta. Propodus relatively narrow, length about 1.3 that of carpus; dorsal margin with one distal long simple and two stout spiniform setae, and large and small seta; ventral margin with four stout spiniform setae decreasing in size proximally stout bipectinate seta on inner face adjacent to distal most spiniform seta. Dactylus length about that of propodus, curved ventrally; unguis about one third as long combined length of it and rest of dactylus.

Pereopod-2 ( Fig. 18C ). Basis longer than combined length of merus, ischium, and carpus; usually dorsal margin with two to three blunt teeth rarely (apophyses) and one simple seta on dorsal margin, ventral margin with two short simple setae, longest distal. Ischium with ventrodistal margin bearing single simple seta. Merus about half length of basis, with narrow, spiniform seta on dorsodistal margin, one simple seta on outer face and two simple setae on ventral margin. Carpus as broad as long, with five stout spiniform setae (three on outer face and two on ventral margin), two dorsodistal setae. Propodus about equal in length to merus, ventral margin with row of four stout spiniform setae, decreasing in size proximally; two spiniform setae and one long seta on outer face; short bipectinate seta on inner face adjacent to distal most spiniform seta and one dorsodistal spiniform seta. Dactylus as in pereopod-1.

Pereopod-3 ( Fig. 18D, E ). Generally similar to pereopod-2, but with six spiniform setae on carpus.

Pereopod-4 ( Fig. 18F ). Basis longer than lengths of ischium, merus, and carpus combined, subdorsal margin with two broom setae; dorsal margin lacking apophyses; ventral margin with two simple setae. Ischium with welldeveloped simple seta and small adjacent seta on distoventral margin. Merus with subdistal spiniform and subdistal simple seta, one simple seta on ventral margin. Carpus shorter than merus, with seven, stout spiniform setae and small submarginal, distodorsal simple seta. Propodus having distal margin with five six strongly developed bipectinate setae; ventral margin stout spiniform seta proximally and larger distal spiniform seta. Dactylus similar to those of pereopods 1–3 with unguis about one third of combined length of it and dactylus.

Pereopod -5 ( Fig. 18G, H ). Basis longer than combined length of ischium, merus, and carpus, setation as in pereopod-4. Ischium as in pereopod-4. Merus about 1.5 times length of carpus, with one simple seta on ventral and dorsodistal margin. Carpus longer than broad, with three spiniform setae (one dorsodistal, one ventral and one on outer face), and three simple setae (two long ventrodistal and dorsodistal and one short subdistal). Propodus elongate, approximately twice length of carpus, with sensory (broom) seta on mid-dorsal margin, two welldeveloped pectinate setae on distal/subdistal dorsal margin; ventral margin with two spiniform setae. Dactylus similar, but more robust than that of pereopod-4.

Pereopod-6 ( Fig. 18I, J ). Similar to pereopod-5, except carpus lacking distal spiniform seta on inner and lateral faces. Propodus with subdistal and subproximal spiniform seta on ventral margin not as strongly developed as those on pereopod-5. Dactylus as in pereopopd-5.

Uropod ( Fig. 19E ). Basal article expanded with distal inner margin forming subacute distal process or apophysis, two subdistal small simple setae on ventral margin. Exopod biarticulate (extending to distal margin of second article of endopod); article-1 with one small subdistal simple seta; article-2 with two terminal sensory setae. Endopod with four articles, first two shortest and subequal in length; first asetose; second with short simple seta on distal inner corner; article-3 distinctly longer than article-2 with two broom setae near distolateral margin and short simple seta on distolateral corner; article-4 slightly less than twice the length of article-3, terminating in three long simple setae, one short simple seta and two broom-setae.

Adult male ( Fig. 16C ). Similar to female, but differing in several aspects.

Antennule ( Fig. 16D ). Appearing slightly narrower than in female with outer flagellum having three aesthetascs, two on article 1 and one an article-2.

Pereopods 1–3 (19D). With dorsal margin of basis generally bearing two to four spiniform apophyses, sometimes varying in number on same individual.

Chelipeds ( Figs 16C ; 17K). Symmetrical, similar but more robust and distinctly larger than those of the female; carpus more triangular shaped than in female, two small acute subdistal apophyses on ventral margin ( Fig. 17K ); inner face of propodus (palm) lacking pair of bipectinate setae.

Etymology. The species is named in honor of our colleague Tom Hansknecht, in recognition of his valuable contributions to invertebrate taxonomy and specifically to our knowledge of the Tanaidacea .

Distribution. Southeastern North America off the coasts of South Carolina, SE Florida, and SE Texas (Flower Garden reefs)

Variation. One female of S. hansknechti n. sp. that we examined was heterochelate. Gardiner (1973) also discovered one out of 33 females of Ronabus idios to be heterochelate, which he attributed to aberrancy. We believe that this condition in the specimen we examined may have been caused by the loss of a cheliped and its subsequent regeneration to a smaller size than the original.

Based on the thirty specimens of S. hansknechti examined during our study, the number and shape of the tubercles, apophyses, or spines along the inner margin of antennular peduncle article-1 can differ (see Figs 18A–E ; 19A, B). Variation within the pereopods was largely confined to the spine-like apophyses along the dorsal margins of the basis for pereopods 1–3 ( Figs 18A, C, D ); 19C, D). Generally, two spine-like apophyses are present on the bases of pereopods 1–2, but these can vary from two to three and rarely five. One ovigerous female had three distinct apophyses on the dorsal (anterior) margin of pereopod-1, and five (three large and two small) on pereopod- 2. Further, in one instance there was variation in the number of articles of the uropod; the left uropod of an adult male appeared to exhibit only three endopodal articles; however, the first article had a slight, marginal indentation medially appearing to indicate an incompletely formed article.

Remarks. Synapseudes hansknechti n. sp. can be separated from the other members of the genus by a combination of characters, including (1) functional antennal article-5 (= flagella article-1) appearing to represent the fused vestiges of two articles, (2) propodus of pereopods 1–3 having four blunt spiniform setae on the ventral margins, (3) uropodal endopod having four articles, and (4) pleonites 1–3 being well-delineated with lateral processes each terminating in a blunt spine. Refer to Table 3 and Key for additional characters further distinguishing S. hansknechti from it congeners.

Our description of S. hansknechti is based in part on the specimens of Heard et al. (2004) designated as Synapseudes sp. A; however, their diagnosis and figures (62a, 63a, b, c, and 81) for Synapseudes . sp. A were incorrect since they indicated that only two delineated pleonites, instead of three, were present. Further, the illustration of the antenna of S. intumescens , was inadvertently substituted for the Florida species. Synapseudes sp. A sensu Suárez-Morales et. al. (2004), and García-Madrigal et. al (2005), reported as the same as Synapseudes sp. A sensu Heard et al (2004) from Southeast Florida, is not conspecific with their specimens and may represent an undescribed species or possibly S. erici (R. Heard, per. observ.)

The presence of a partial suture on flagella article-1 of S. hansknechti ( Fig. 16H, I ), which may represent the remnants of an additional article, appears to be unique to S. hansknechti . The possible systematic significance of this character is uncertain. It may indicate the vestige of a true flagella article or it may be a secondarily derived character. If the former, it may be comparable to the unfused articles-5 and 6 present on the antenna of Ronabus idios (see Fig. 3B ).

Synapseudes hansknechti is the fourth member of the genus to be described from the western Atlantic. Synapseudes rectifrons was described from the southwestern Atlantic off Brazil, while Synapseudes pinosensis , originally placed in the monotypic genus Synapseudoides , is the first member of the genus described from the northwestern Atlantic (southwest coast of Cuba). Another northwestern Atlantic species, S. erici was described from the Virgin Islands (type locality) and Bermuda.

In S. hansknechti , as in S. mediterraneus , the delineated pleonites present are well-developed with distinct lateral processes (see Figs 16G ; 4G, H, respectively). In S. hansknechti however, three instead of two pleonites are present. As alluded to earlier in our Remarks for the genus Synapseudes, Băcescu (1977) speculated that acute ventrolateral process on pleonites 1 and 2 of S. mediterraneus may represent vestiges of pleopods. However, we consider these processes and those exhibited by S. hansknechti to be the remnants of ventrolateral tips of the abdominal pleura. The presence of ventrolateral, tuberculate processes may be present on the pleonites in other species of Synapseudes , but may not be as evident unless the abdomen is being examined in dorsal aspect under slight coverslip pressure.

Due to the variation observed in the antennules, pereopods 1–3, chelipeds, and uropods of the material that we examined, such characters should be used with caution in cladistic and PCA analyses, especially when only one or two specimens are available for study. It also should be noted that some incubatory females of S. hansknechti were approximately 0.5 mm larger than others having oöstegites. This suggests, as we earlier mentioned for the larger females attributed to S. minutus , that adult females of S. hansknechti may represent at least two reproductively active instars of different size.

Figures

FIGURE 3. Metapseudes wilsoni. A, antenna; C, right mandible with palp; H, uropod, endopod biarticulate. Metapseudes aucklandiae. E, abdomen, pleonites completely delineated (five pairs of biramous pleopods not illustrated); F, biramous pleopod with terminal setulate setae; G, pleonites 4–5 and pleotelson, dorsal aspect. Ronabus idios. B, antenna; D, left mandible with palp.I, male pleon and pleotelson, lateral aspect,showing partially fused pleonites1–5 and biramous pleopod-1; J, female, uniramous pleopod-1; K, partially fused pleonites and pleotelson, dorsal aspect; L, uropod, endopod triarticulate. A, C, H from Błażewicz-Paszkowycz & Bamber (2007); B, D–G, I–L from, or modified from, Gardiner (1973).

FIGURE 16. Synapseudes hansknechti n. sp. Adult female. A, dorsal aspect, (oöstegites not shown); ovigerous female 2.1 mm: B, dorsal aspect, showing orientation of pereopods; adult male 2.2 mm: C, lateral view showing enlarged symmetrical chelipeds; antennules (D–F): D, adult male, dorsal aspect; E, adult female, dorsal aspect; F, adult female, ventral aspect; adult female: G, abdomen and pleotelson, slightly compressed dorsoventrally to show lateral tubercles on ventrolateral margins of pleonites 1–3; adult male: H, I, right and left antennae, dorsal and ventral aspects, respectively. Scale line 1 for A = 0.5 mm; Scale line 2 for D–F, = 0.1 mm; and for H, I = 0.05 mm; Scale line 3 for G = 0.1mm.

FIGURE 17. Synapseudes hansknechti n. sp. Adult female. A, left mandible showing enlargement of quadridentate lacinia mobilis B, right mandible; C, maxillule; D, maxilla; E, labium, part of right lobe showing palp; F, maxilliped, medial aspect indicating secondary fusion of endites; G, right endite of maxilliped, inner face; H, epignath; I, cheliped, lateral aspect of fixed finger and dactylus showing details of dentition and setation; J, chela, lateral aspect. Adult male. K, cheliped, lateral aspect. Scale line for A–H = 0.05 mm; for J, K = 0.1mm.

FIGURE 18. Synapseudes hansknechti n. sp. Adult female. A, pereopod-1, left, lateral aspect; B, pereopod-1, right, dactylus and distal part of propodus, inner aspect; C, pereopod-2, left, lateral aspect; D, pereopod-3, lateral aspect; E, pereopod-3, inner aspect, excluding basis; F, pereopod-4, left, posterior orientation; G, pereopod-5, right, inner aspect, posterior orientation; H, pereopod-5, left, posterior orientation of carpus, propodus, and dactylus, lateral aspect; I, pereopod-6, posterior orientation; J, right, inner face of dactylus, propodus, and distal part of carpus, lateral aspect. Scale line for A–J = 0.1 mm.

FIGURE 19. Synapseudes hansknechti n. sp. A–C, E: Ovigerous female, A, B, variation in spines on antennular peduncle, dorsal aspects; C, basisof pereopod-1, dorsal aspect; E, righturopod, adultfemale,dorsal aspect.Male.D, basisof pereopod-1, dorsal aspect.Scale line = 0.1 mm.