Synapseudes singularis Stępień & Błażewicz, 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 : 327-332

Synapseudes singularis Stępień & Błażewicz , n. sp.

Figures 13–16

Diagnosis. Cephalothorax rostrum blunt, distal margin slightly concave. Antennule with peduncle article-1 relatively narrow, about 3.3 times longer than wide, with inner, medial margin armed with single spiniform apophysis or spiniform process. Antenna with six articles, terminating in two long setae. Maxilliped with endite having four coupling hooks. Pereopods 1–3 propodus ventral margin with four spiniform tooth-like setae. Pleonites 1–3 completely delineated. Uropod endopod with four articles. Male unknown.

Material examined. Holotype— female (W53960), CGLI 36 A, 14.38536°S, 145.26599°E, Lizard Island , Granite Bluff, fore reef (mid shelf), coarse coral rubble, depth 15 m, coll. MB.

Paratypes — One ♀ (W53961), CGLI 25 C, 14.64567°S, 145.45325°E, Lizard Island, North Head, fore reef (mid shelf), depth 12 m, coll . C. Glasby (CG); five ♀♀ (W53962), CGLI 36 A, parameters as for holotype; two ♀♀ CGLI 0 39, 14.64064°S, 145.45365°E, Lizard Island , Mermaid Cove , North Point, ‘ Washing Machine’, depth 15 m ; three ♀♀ (W53964), CGLI 039 C; two ♀♀ (W53965), CGLI 040 A, 14.38567°S, 145.29132°E, Lizard Island , MacGillivray’s Reef, smooth rubble, depth 18 m ; two ♀♀ (W53966), LIZ 09-10 C, 14.61383°S, 145.6182°E, Lizard Island , Yonge Reef, back reef, dead coral heads, depth 12 m, coll . NLB & MB; two ♀♀ (W53967), LIZ 09- 10E, coral rubble at edge of bommies, depth 7 m; 15 (W53968), LIZ 09-21 A, 14.74669°S, 145.31670°E, Lizard Island , North Direction Island, reef front, dead coral heads, depth 12 m, coll. MB & C. Arango (CA).

Description of adult female. Body ( Fig. 13A, B ). About 1.25 mm long, 4.7 times longer than wide.

Cephalothorax ( Fig. 13A, B ). About 26% of total body length; rostrum blunt, distal margin slightly concave; eyes with dark pigment and ommatidia.

Pereon ( Fig. 13A, B ). About 62% of body length; pereonites rectangular, pereonites 1, 2 and 4 similar in length, about 0.4 times as long as wide, pereonites 2 and 5 about half as long as wide, pereonite-6 narrowest, about 0.3 times as long as wide; first four pereonites with lateral setae on anterior corner, last two pereonites with additional pair of mid-dorsal setae.

Pleon ( Fig. 13A, B ). About 12% of body length, consisting of three delineated pleonites and pleotelson; all pleonites similar in length.

Pleotelson ( Fig. 13A, B ). About 2.3 times as long as combined length of pleonites, with pair of stout setae on dorsal surface.

Antennule ( Figs 13A, B ; 14A). Peduncle article-1 about 3.3 times as long as wide, with two broom setae, three simple setae and one strong spiniform apophysis on outer margin, and with three inner broom setae, and small distal; apophyses; article-2 about half as long as article-1, with five simple setae, three small spine-like apophyses, and three distal broom; article-3 with two distal setae; article in common with two distal setae. Inner flagellum with three articles, article-1 with aesthetasc, article-2 with distal seta and one aesthetasc; article-3 with three distal setae. Outer flagellum with two articles, article-2 terminating in three long, simple setae.

Antenna ( Figs 13B ; 14B). Peduncle with four articles: article-1 robust, with serrate inner margin and two distal apophyses; article-2 with four apophyses and simple seta; article-3 with three distal apophyses; article-4 longest, about twice that of article-3, with five broom setae along distal margin; flagellum with two articles terminating in two long subequal setae.

Mandible ( Fig. 14C ). Incisor with two blunt lobes, setiferous lobe with reduced, bifurcate lacinia mobilis and three simple setae; molar distally serrate; palp with three-articles, articles 1 and 2 asetose, article-3 with two distal pectinate setae.

Maxillule ( Fig. 14D, E ). Outer endite ( Fig. 14E ) having eight spines and simple setae along outer margin; inner endite ( Fig. 14D ) with four setulate distal setae; palp ( Fig. 14F ) with two long finely pectinate terminal setae.

Maxilliped ( Fig. 14G, H ). Basis as long as wide, naked. Palp article-1 short, compressed, lateral margin expanded and terminating in large robust spine; inner distal margin with long, simple seta extending distally to article-2. Article-2 slightly shorter than wide with four basally swollen, distally pectinate setae and six simple setae (proximal most being longer than article-2). Article-3 slightly longer than wide with five basally swollen, distally pectinate setae, and two short submarginal setae on inner margin. Article-4 about 1.5 times as long as wide, with two basally swollen, distally pectinate setae and three simple setae (subdistal seta distinctly longer than the other two). Endite ( Fig. 14 G’) having inner margin with four coupling hooks and two subdistal setulose setae, and with four distal setulose setae and one setulose spine.

Epignath ( Fig. 14I ). With long distal pectinate seta.

Cheliped ( Fig. 14J ). Basis 1.3 times as long as wide, with three setae along ventral margin. Merus twice as long as wide, with three ventral setae. Carpus 3.3 times as long as wide, with two ventral setae and one subdistal spine. Propodus half as long as carpus, with two setae near insertion of dactylus; fixed finger with three ventral setae and four inner setae.

Pereopod-1 ( Fig. 15A ). Basis less than three times as long as wide; ventral margin with three setae, one distal; dorsal margin with single spiniform, subacute, apophysis and three small setae. Ischium narrow, about 0.3 times as long as wide, with one ventral seta. Merus about 1.7 times as long as wide; ventral margin with one seta and one subdistal spiniform seta; dorsal margin with well-developed buttressed distal spiniform seta. Carpus 0.6 times as long as merus; ventral margin with two stout spiniform setae; dorsal margin with large spiniform seta and three distal setae. Propodus subequal to merus; ventral margin with four spiniform setae decreasing in size proximally, one stout setulose seta distally near insertion of dactylus; dorsal margin with broom seta, with one distal stout spiniform and one long, simple seta; inner subdistal face with stout spiniform seta. Dactylus 0.3 times as long as propodus, with one ventral and one dorsal seta; unguis 0.6 times as long as dactylus

Pereopod-2 ( Fig. 15B ). Similar, but distinctly smaller than pereopod-1. Basis less than three times as long as wide; ventral margin with two setae, one distal; dorsal margin with single spiniform, apophysis, one simple and two broom setae. Ischium narrow, about 0.3 times as long as wide with one ventral seta. Carpus half as long as merus; ventral margin with two stout spiniform setae; distodorsal and subdistal margins with simple seta and two spiniform plus simple seta, respectively. Propodus about 0.8 times as long as merus, ventral margin with four spiniform setae decreasing in size proximally along ventral margin and short, distal stout setulate seta; dorsal margin with one broom seta, spiniform seta and distal long simple seta; inner subdistal face with stout spiniform seta. Dactylus 0.3 times as long as propodus, with one ventral and one dorsal seta; unguis 0.6 times as long as dactylus.

Pereopod-3 ( Fig. 15C ). Similar to pereopod-2, but merus 2.5 times as long as wide, and dactylus half as long as propodus.

Pereopod-4 ( Fig. 15D ). Basis 3.5 times as long as wide, with two broom setae on dorsal and ventral margin and one simple setae distoventrally. Ischium with one ventral seta, Merus about 1.2 times as long as wide with one spiniform seta and two simple setae along inner subdistal margin. Carpus subequal to merus, with one simple seta and six spiniform setae. Propodus 1.6 times as long as merus; ventral margin with one proximal and one subdistal spiniform setae, small setulate seta subdistally; dorsal margin with broom seta (not illustrated), four distal setulate, and with small ventral spine, with one spines and plumose seta ventrally and four plumose distodorsal setae. Dactylus half as long as wide, with small ventral and dorsal setae; unguis 0.3 times as long as dactylus.

Pereopod-5 ( Fig. 15E ). Basis 3.5 times as long as wide, ventral and dorsal margins with one and two broom setae, respectively. Ischium 0.3 times as long as wide, with one ventral seta. Merus 1.6 times as long as wide with submarginal long distal seta and short subdistal seta. Carpus 0.7 times as long as merus, with three spines and two setae distally and subdistally. Propodus four times longer than wide; ventral margin with one small subproximal and one large subdistal spiniform seta, dorsal margin with broom seta and three distal setulate setae. Dactylus similar to that of pereopod 4.

Pereopod-6 ( Fig. 15F ). Basis 3.6 times as long as wide; ventral margin with two small setae; dorsal margin with two broom setae. Ischium 0.3 times as long wide, with one ventral seta. Merus 1.6 times as long as wide, ventral margin with subdistal simple seta, dorsal margin with small distal spiniform seta. Carpus 0.9 times as long merus, with one spine and one distoventral seta, and one distodorsal seta. Propodus twice as long as merus, with small ventral spine, dorsal broom seta, one distoventral spine and three plumose distodorsal setae. Dactylus 0.4 times as long as propodus, with ventral and dorsal seta; unguis 0.6 times as long as dactylus.

Uropod ( Fig. 14K ). Basal article twice as long as wide, with strong apophysis on inner distal margin; exopod biarticulate, distal article terminating in two setae; endopod with four articles, article-3 with two distal broom setae, article-4 terminating in two broom setae and three long simple distal setae.

Male. Unknown.

Etymology. The specific name singularis is derived from Latin meaning ‘one’ or ‘single’, referring to the single spiniform apophysis occurring in the inner mid-margin of antennular article-1.

Remarks. Synapseudes singularis n. sp., S. dispina ; and S. intumescens are distinguished from the other 23 members of the genus by having a combination of the (1) antenna terminating in two long setae, (2) propodus of pereopod-1 with ventral margin having four spiniform setae, (3) first three pleonites completely delineated, and (4) uropod with endopod having four articles. Synapseudes singularis can be separated from S. dispina , S. intumescens and the other members of the genus by having the first peduncular article of the antennule being relatively narrow (about 3.3 times longer than wide) and its inner medial margin armed with a single spiniform apophysis. Also, S. singularis appears unique by having pereopods 1–3 each with a single spiniform apophysis on ventral margin of the basis. For additional characters distinguishing Synapseudes singularis and other members of the genus, refer to Table 3 and Key presented here.

Figures

FIGURE 13. Synapseudes singularis n. sp. Female holotype.A, body dorsal view; B, body lateral view.Scale line = 1mm.

FIGURE 14. Synapseudes singularis n. sp. Female holotype.A, antennule; B, antenna; C, right mandible; D, maxillule, inner endite; E, maxillule, outer endite; F, maxillule, palp; G, maxilliped, endite; H, maxilliped, basis and palp; I, epignath; J, left cheliped, lateral aspect; K, uropod. Scale line = 0.1mm.

FIGURE15. Synapseudes singularis n. sp. Adult female.A–F,pereopods 1–6 respectively, inner aspect.Scaleline = 0.1 mm.

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.