Francapseudes uniarticulatus Băcescu, 1981

Esquete, P. & Cunha, M. R., 2017, The Apseudomorpha (Crustacea: Tanaidacea) of the Gulf of Cadiz and Horseshoe Continental Rise (NE Atlantic): A taxonomic review with new records, species, and ecological data, Zootaxa 4276 (1), pp. 61-95 : 81-85

Francapseudes uniarticulatus Băcescu, 1981

( Figs 13–15 )

Francapseudes uniarticulatus Băcescu, 1981:62 –63, figs. 10, 11I. Guţu 1991:83 (key).

Remarks. The material from GoC is described and illustrated here to complement the original description.

Material examined. Gulf of Cadiz—Mud volcanoes. Darwin MV: St. TTR16_AT608, 1115 m, 4 ♀♀, 1 ovigerous ♀, 2 neuters ( DBUA 0002011.01 ) ; St. TTR17-2_AT664, 1128 m, 8 specimens 3 ♀♀, 5 neuters (DBUA0002012.01).

Description of female with oostegites. Body ( Figure 13 A, B) 6.4 mm length, 5.5 times as long as broad. Cephalothorax as long as pereonites 1–2; rostrum truncate; eyelobes present, without visual elements. Pereon, all pereonites with lateral setae, pereonite 1 0.5 times as long as broad, pereonite 2 0.8 times as long as pereonite 1, pereonite 3 0.6 times as long as broad, pereonites 4–5 about as long as broad, pereonite 6 0.7 times as long as broad. Pleon 0.1 times as long as body length; pleonites alike, with acute lateral projections directed posteriorly, lateral margins with setae. Pleotelson about as long as wide, indented laterally on uropod insertions, posterior margin tapering, lateral margins with four setae.

Antennule ( Figure 13 C) peduncle article 1 4.2 times as long as broad, inner margin with five long setae; article 2 1.5 times as long as broad, inner margin with three subdistal long simple setae and one distal penicillate seta; article 3 0.8 times as long as broad, with two distal setae. Flagellum common article naked; outer (main) flagellum of four segments, first segment 1.5 times as long as broad, with two distal setae, second segment 0.6 times as long as first and bearing setae and one aesthetasc, third segment as long as second, bearing setae and one aesthetasc, fourth segment as long as previous, bearing setae; inner (accessory) flagellum of two segments, both bearing a seta.

Antenna ( Figure 13 D) article 1 wider than following articles, with cuticular scales, inner distal margin crenulated; Article 2 2.6 times as long as broad, bearing squama, squama 3.0 times as long as broad, bearing a long, distal, flagellum-like seta; article 3 0.7 times as long as broad, with one short distal seta; article 4 6.4 times as long as broad, inner margin with two medial penicillate setae, inner distal corner with one short and one long setae and one aesthetasc, outer margin with two subproximal, one medial and one subdistal penicillate setae. Flagellum of four segments, first segment 0.2 times as long as peduncle article 4, with two inner penicillate seta and one? aesthetasc; second segment as long as first, with one distal penicillate and simple seta and distolateral aesthetasc; third segment 0.5 times as long as second, with seta; distal segment as long as previous, with tuft of distal setae.

Mouthparts. Labrum (not illustrated) quadrate, naked. Left mandible ( Figure 14 A) molar with distal setules; incisor crenulated; lacinia mobilis with four unequal denticles; setal row consisting of four pectinate setae; palp uniarticulate 0.6 times as long as mandible, bearing distal, flagellum-like seta. Right mandible ( Figure 14 B) as left but without lacinia mobilis, setal row consisting of three pectinate setae and two bi- and trifurcate setae. Maxillule outer endite ( Figure 14 C) with eleven distal spines, outer margin with two spinules; inner endite ( Figure 14 D) with four distal spines, outer margin with three spinules; palp ( Figure 14 E) biarticulate, with one plumose seta. Maxilla ( Figure 14 F) outer lobe of movable endite with six pectinate spines; inner lobe of movable endite with three pectinate spines; outer lobe of fixed endite with five bifurcate spines; inner lobe of fixed endite with row of simple setae.

Maxilliped palp ( Figure 14 G) article 1 outer distal corner with seta, inner distal corner with one long, bipinnate seta; article 2 with one outer distal plumose seta, inner margin with a row of five simple and seven pinnate setae; article 3 with inner row of six pinnate setae; article 4 with six pinnate setae; endite ( Figure 14 H) with two coupling hooks, inner margin with inner row of six circumplumose setae, distal margin with five pectinate spines and outer distal seta.

Cheliped ( Figure 15 A) basis about as long as broad, ventral margin with seta, dorsal margin with seta. Merus 0.7 times as long as basis, with ventrodistal setae. Carpus 2.4 times as long as basis, 2.3 times as long as broad, with three ventral setae. Chela 1.4 times as long as carpus, 2.3 times as long as broad; propodus palm with two setae near dactylus insertion; fixed finger with distal claw and three setae on ventral margin, cutting edge with proximal blunt tooth and simple seta, followed by spinules; dactylus as long as propodus, with medial tuft of three setae.

Pereopod 1 ( Figure 15 B) coxa naked; basis 2.8 times as long as broad, with two ventrodistal setae. Ischium with ventral seta. Merus about as long as basis, with one ventrodistal spine, one seta and one dorsodistal spine. Carpus 1.6 times as long as merus, with three dorsal setae, one dorsodistal spine, ventral margin with two proximal and one distal seta and three spines. Propodus 0.5 times as long as carpus, dorsodistal corner with two spines, one 0.5 times as long as the other, and two setae, ventral margin with two spines, distal margin with one seta. Dactylus and unguis together 0.9 times as long as propodus, with two ventral triangular apophyses; unguis 0.2 times as long as dactylus.

Pereopod 2 ( Figure 15 C) coxa naked; basis 5.0 times as long as broad, dorsal margin with one proximal penicillate seta, ventral margin with one long distal, one subdistal, and one proximal simple seta. Ischium with ventrodistal seta. Merus 0.4 times as long as basis, ventral margin with one medial and one distal seta, dorsal margin with distal seta. Carpus 1.2 times as long as merus, with two ventral spines, four dorsal long setae, one short dorsodistal seta and one short dorsodistal spine. Propodus 1.2 times as long as carpus, 3.8 times as long as broad, with three ventral spines, one ventrodistal seta, four dorsodistal setae and one subdistal, mesial short spine. Dactylus and unguis together 0.7 times as long as propodus, dactylus with short dorsal spine, unguis 0.5 times as long as dactylus.

Pereopod 3 ( Figure 15 D) coxa naked; basis 3.9 times as long as broad, with medial penicillate seta and ventrodistal simple seta. Ischium with ventrodistal seta. Merus 0.4 times as long as basis, ventral margin with medial seta, one distal simple seta and one distal penicillate seta, dorsal margin with distal seta and spine. Carpus 1.3 times as long as merus, dorsal margin with three setae, dorsodistal corner with spine, ventrodistal corner with spine and seta. Propodus 1.1 times as long as carpus, ventral margin with four spines, dorsal margin with one penicillate and three subdistal simple setae, distal margin with small spine. Dactylus and unguis together 0.6 times as long as propodus, unguis 0.5 times as long as dactylus.

Pereopod 4 ( Figure 15 E) coxa naked; basis 3.6 times as long as broad, with one ventromedial penicillate seta and two ventrodistal simple setae. Ischium with ventrodistal seta. Merus 0.4 times as long as basis, with three ventrodistal and one dorsodistal setae. Carpus 1.4 times as long as merus, dorsodistal corner with spine and two setae (one long and one short), ventral margin with one medial and two distal spines, distal margin with two long setae. Propodus as long carpus, ventral margin with three spines and one seta, dorsal margin with penicillate seta, distal margin with one simple and eight serrulate spines. Dactylus and unguis together 0.7 times as long as propodus, unguis 0.5 times as long as dactylus.

Pereopod 5 ( Figure 15 F) coxa with seta. Basis 3.6 times as long as broad, with ventromedial penicillate seta and two ventrodistal setae. Ischium with ventrodistal seta. Merus 0.4 times as long as basis, with two dorsodistal and three subdistal setae. Carpus 1.3 times as long as broad, with four ventral setae and two ventral spines. Propodus 0.9 times as long as broad, with four mesial short setae, four subdistal pectinate spines, ventral spine and dorsal penicillate seta. Dactylus and unguis together 0.8 times as long as propodus, unguis 0.5 times as long as dactylus.

Pereopod 6 as pereopod 5.

Pleopod ( Figure 15 G) basis biarticulate; proximal article 0.2 times as long as distal article, distal article almost as long as endopod, with distal plumose seta. Endopod biarticulate, distal article 8.5 times as long as proximal, with five distal plumose setae. Exopod uniarticulate, with one medial plumose seta on outer margin and five distal plumose setae.

Uropods (not illustrated) basis 4.1 times as long as broad, naked. Exopod of two segments, endopod of about 20 segments.

Remarks. The material described and illustrated here shows minor differences with the original description. Namely, illustrations by Băcescu (1981) show two setae on the antennal squama, the pereopod 1 propodus without short distal spine, and the pereopod 2 carpus with one only one ventral spine and three dorsal long setae, and dorsal margin with no spine.

Distribution and ecology. Our material was retrieved from Darwin MV, at 1115 and 1128 m depth; the samples were composed of mud with Bathymodiolus shells and authigenic carbonate crusts. The only previous record in the Bay of Biscay was found at 170–900 m, on substrates with rocks and corals.

Figures

FIGURE 13. Francapseudes uniarticulatus. Female DBUA 0002012.01 a. A, habitus (dorsal view). B, habitus (lateral view). C, antennule. D, antenna.

FIGURE 14. Francapseudes uniarticulatus. Female DBUA 0002012.01 a. A, right mandible. B, left mandible. C, maxillule outer endite. D, maxillule inner endite. E, maxillule palp. F, maxilla. G, maxilliped palp. H, maxilliped endite.

FIGURE 15. Francapseudes uniarticulatus. Female DBUA 0002012.01 a. A, cheliped. B, pereopod 1. C, pereopod 2. D, pereopod 3. E, pereopod 4. F, pereopod 5. G, pleopod.