Apseudopsis rogi Esquete

Esquete, Patricia, Ramos, Eva & Riera, Rodrigo, 2016, New data on the Tanaidacea (Crustacea: Peracarida) from the Canary Islands, with a description of a new species of Apseudopsis, Zootaxa 4093 (2), pp. 248-260 : 250-256

Apseudopsis rogi Esquete , sp. nov.

Material examined. Holotype —male II MNCN 20.04/10183, station LC 4-C, Los Cristianos harbour, Tenerife, 28º 2’ 49’’ N, 16º 42’ 53’’W, 11 m depth, unvegetated sand, “Cak Foster” dredge, September 2013, coll. E. Ramos & R. Riera.

Paratypes —copulatory female allotype MNCN 20.04/10184; three male II MNCN 20.04/10185; male II MNCN 20.04/10186; male II MNCN 20.04/10187; preparatory female MNCN 20.04/10188, two copulatory females and eight male II, DBUA0001872.01-02 station LC 4-C, 28º 2’ 49’’ N, 16º 42’ 53’’W, 11 m depth, unvegetated sand; “Cak Foster” dredge, September 2013, coll. E. Ramos & R. Riera.

Other material —six juveniles, six preparatory females, four males, DBUA0001873.01-03, station LE 4-C, 27º 46’ 55’’N, 17º 54’ 9’’W, 6 m depth, unvegetated sand; All “Cak Foster” dredge, September 2013, coll. E. Ramos & R. Riera.

Etymology. Named after Roger N. Bamber, also known as “Rog”, in recognition of his great contribution to the knowledge of the Tanaidacea .

Diagnosis. Apseudopsis with no marked posterolateral apophyses nor ventral hyposphenia on pereonites; rostrum pointed with rounded anterolateral margins; antennular inner flagellum with three segments, outer flagellum with nine segments; pereopod 1 merus without dorsodistal spine, propodus with four ventral spines; male II cheliped basis as long as broad, merus with dorsoproximal spur, propodus ventral margin perpendicular to cutting edge, cutting edge with proximal invagination followed by rounded apophysis; uropod outer ramus of three segments.

Description. Male II paratype MNCN 20.04/10185. Body ( Figure 2 A) length 3 mm, 5.3 times as long as broad. Cephalothorax about as long as broad, as long as pereonites 1–2, rostrum pointed with rounded shoulders (anterolateral margins); eyelobes with ommatidia present. Pereon with pereonites all without apophyses, without hyposphenians, margins with scattered setae. Pleon 0.14 times as long as body, pleonites ( Figure 2 A, B) alike, lateral margins pointed with simple setae. Pleotelson ( Figure 2 B) about as long as broad, lateral margins with simple setae, distal margin with two subdistal pairs of one simple and one penicillate setae.

Antennule ( Figure 2 C) peduncle article 1 3.1 times as long as broad, inner margin with simple setae, outer margin with proximal tuft of three penicillate setae, medial tuft of two simple and two penicillate setae, subdistal tuft of five simple setae and two penicillate setae; article 2 0.4 times as long as article 1, subdistally with nine simple setae and four penicillate setae; article 3 0.4 times as long as article 2, inner margin with five simple setae, outer margin with three distal setae. Flagellum common article naked; inner flagellum of three segments, segments 1 and 3 with setae, outer flagellum of nine segments, all segments with setae, segments 1–7 with one aesthetasc each.

Antenna ( Figure 2 D) peduncle article 1 1.2 times as long as broad, inner lobe with two small setae; article 2 1.3 times as long as broad, with inner small seta, bearing squama with 15 long marginal setae; article 3 0.3 times as long as article 2, 0.7 times as long as broad, with one long inner seta; article 4 1.6 times as long as article 3, with inner penicillate seta; article 5 1.5 times as long as article 4, twice as long as broad, with two inner proximal simple setae, two distal simple setae, two inner distal penicillate setae and two inner medial penicillate setae. Flagellum of six segments, all bearing inner short and outer long setae.

Mouthparts. Labrum (not illustrated) bilobed, with setules. Right mandible ( Figure 3 A) molar ( Figure 3 B) triturative, with spiniform processes; pars incisiva with four denticles; setiferous lobe with five bifurcate and trifurcate setae. Palp article 1 1.3 times as long a broad, with ten setae on inner margin; article 2 1.7 times as long as article 1, 4.1 times as long as broad, with row of five pectinate spines, proximal spine longest; article 3 0.5 times as long as article 2, 3.7 as long as broad, with seven subterminal pectinate spines, one subterminal seta and three terminal setae. Left mandible ( Figure 3 C) with tridentate lacinia mobilis and setiferous lobe bearing four multifurcate setae; pars incisiva with four denticles. Maxillule ( Figure 3 D) inner endite with marginal apophysis, bearing five distal setulose setae; outer endite bearing eight distal spines and two subdistal pectinate setae, outer and inner margin with fine setae; palp ( Figure 3 E) with four terminal setae. Maxilla ( Figure 3 F) outer margin serrated, outer lobe of fixed endite with simple setae, and bifurcate, trifurcate and pectinate spines. Inner lobe of fixed endite with row of numerous simple setae in front of two pectinate setae. Outer lobe of movable endite with five pectinate setae, a row of six simple setae, and two strong, plumose setae with medial setules on outer margin. Inner lobe of movable endite with five pectinate setae. Labium (not illustrated) with outer margin serrated, palp with three distal setae and marginal setae and setules.

Maxilliped basis simple; palp ( Figure 3 G) first article with one longer inner seta and outer distal spine; second article inner margin with 21 setae, outer margin with one distal seta; third article with eight setae along inner margin; distal article with six distal setae; endite ( Figure 3 H) inner margin with row of spines, distal margin with setules, row of bilobed setae, one subdistal long seta, and outer corner with row of five simple setae. Epignath (not illustrated) as in other species of the genus, with one circumplumose seta.

Cheliped ( Figure 4 A) exopod first article 3.1 times as long as broad, naked, distal article pentagonal, with five plumose setae; basis robust, as long as broad, with one ventral spine and seta, ventrodistal tuft of three setae and five dorsal setae. Merus posteriorly with a dorsal marked spur, ventrally with tuft of nine setae. Carpus 2.3 times as long as broad, with one dorsodistal and five ventral setae, and one inner distal simple seta. Chela robust and compact, propodus 1.2 times as long as broad, dorsal margin almost parallel to ventral margin, ventral margin perpendicular to cutting edge, fixed finger with four ventral and three dorsodistal setae, palm inner face with four setae near dactylus insertion and a row of seven setae and three more setae near cutting edge, cutting edge with proximal invagination followed by rounded apophyses, rest slightly convex with spinules. Dactylus with two dorsal setae.

Pereopod 1 ( Figure 5 A) exopod first article 3.1 times as long as broad, naked, distal article pentagonal, with five plumose setae; coxa with anterior apophysis and anterodorsal a tuft of five simple setae. Basis about twice as long as broad, with two dorsal short simple setae and tuft of simple setae on ventrodistal corner. Ischium with two ventral simple setae. Merus broader distally, with lateral row of four setae, dorsodistal tuft of setae, ventral margin with row of setae, and ventrodistal spine. Carpus 0.8 times as long as merus, bearing two distal and two ventral setae, a dorsodistal tuft of setae, and two ventral and one dorsodistal spines. Propodus about as long as carpus, with two distal and four ventral spines; dorsal and ventral margins with setae. Dactylus and unguis about 0.8 times as long as propodus, dactylus with two dorsal and one ventral spinules.

Pereopod 2 ( Figure 5 B) basis cylindrical, 2.7 times as long as broad, with five dorsoproximal setae, five ventrodistal setae and three ventral medial setae. Ischium 0.7 times as long as broad, with four ventral setae. Merus broader distally, with four dorsodistal setae, row of twelve ventral setae, and one ventrodistal spine. Carpus 0.9 times as long as merus, with dorsal and ventral setae, one dorsodistal and one ventrodistal spine. Propodus as long as carpus plus half of merus, three times as long as broad, dorsal margin with six setae, ventral margin with eight setae, subproximal and subdistal thin spines, distal margin with three two thin spines and three setae. Dactylus and unguis together 0.7 times as long as propodus, with dorsodistal setule.

Pereopod 3 ( Figure 5 C) basis with two subproximal setae, one medial seta, two subdistal setae, and four ventrodistal setae. Ischium wider than long, with one ventral setae. Merus with two ventral spines and eight ventral setae. Carpus as long as merus, with lateral row of three spines and six setae, ventral margin with row of setae. Propodus with lateral row of three spines, one ventral spine, three terminal serrate spines, one dorsal penicillate seta and simple setae on ventral, dorsal and terminal margins. Dactylus and unguis about as long as propodus, dactylus with dorsal setule.

Pereopod 4 ( Figure 5 D) basis about twice as long as broad, naked. Ischium with four ventral setae. Merus with three ventral spines and seven simple setae. Carpus 1.4 times as long as merus, with nine ventral spines and several simple setae. Propodus 0.8 times as long as carpus, with seven ventral setae, one dorsal penicillate seta, distally with six short and nine long pectinate spines. Dactylus and unguis together 0.9 times as long as propodus.

Pereopod 5 ( Figure 5 E) basis about twice as long as broad, with two dorsal penicillate setae and two ventrodistal simple setae. Ischium wider than long, with two simple setae. Merus with three ventral spines, five ventral setae and one dorsal seta. Carpus twice as long as merus, ventrally with eight spines and 13 simple setae. Propodus 0.8 times as long as carpus, with eight ventral spines, four ventral setae and one dorsal penicillate seta. Dactylus and unguis together 0.8 times as long as propodus, dactylus with one ventral setule.

Pereopod 6 ( Figure 5 F) basis fusiform, about twice as long as broad, dorsal and ventral margins with row of twelve plumose setae, ventral margin distally with row of five simple setae, ventrodistal corner with four simple setae. Ischium wider than long, with two ventral simple setae. Merus wider distally, dorsal margin with three plumose setae, ventral margin with eleven simple setae, distal margin with one medial simple seta, ventrodistal corner with spine. Carpus 1.5 times as long as merus, with two ventral rows of five spines, ventral margin with nine simple setae, dorsal margin with seven plumose setae. Propodus 0.7 times as long as carpus, with a row of four lateral spines, ventral margin with one proximal short spine followed by a row of pinnate spines that continues along distal margin, dorsodistal margin with one long spine. Dactylus and unguis about as long as propodus, dactylus bearing a dorsal setule.

Pleopods 1 and 2 bases with five inner and six outer plumose setae; pleopods 3 and 4 with five inner and three outer plumose setae; pleopod 5 ( Figure 5 G) with three inner and three outer plumose setae. Both rami with numerous distal and outer marginal plumose setae, endopod with one inner marginal plumose seta.

Uropods ( Figure 2 B) basis with 5 distal setae. Endopod with over 30 segments, many of them with simple setae. Exopod with three segments, proximal segment shortest, distal segment about as long as first two segments, bearing two distal setae.

Preparatory female paratype MNCN 20.04/10188. Pereonite 6 with hyposphenium. Cheliped ( Figure 4 B) exopodite present, as in male; basis 1.5 times as long as broad, dorsal margin with three proximal and two medial simple setae, ventral margin with simple seta and spine and pair of distal setae. Merus as long as basis, ventral margin with tuft of nine simple setae. Carpus cylindrical, 0.9 times as long as merus, ventral margin with 12 simple setae, dorsodistal corner with two setae, outer face with three setae proximally and two setae subdistally. Propodus dorsal margin with one dorsal setae and four setae near dactylus insertion, ventral margin four setae near claw; palm with two setae and tuft of six setae near dactylus insertion; cutting edge with row of setules. Dactylus with tuft of tree dorsal setae.

Otherwise as male.

Juveniles. Antennule inner flagellum of 7–9 segments. Otherwise as preparatory female.

Remarks. Species of Apseudopsis are distinguished by a combination of characters that do not vary through the developmental stages, as follows (see Esquete et al., 2012a): Shape of the rostrum, presence of apophysis on pereonites, presence or absence of dorsodistal spine on pereopod 1 merus, and number of ventral spines on pereopod 1 propodus. Other diagnostic characters include the number and position of hyposphenia on juveniles II and females, and features of the male II cheliped. The number of segments of the antennular flagella are useful for mature specimens (i.e. preparatory, copulatory and intermediate females and males II) of certain species. Apseudopsis rogi sp. nov. has a pointed rostrum with rounded shoulders, pereonites without apophyses, absence of dorsodistal spine on pereopod 1 merus, four ventral spines on pereopod 1 propodus, females with hyposphenium on pereonite 6 only. The most notable character of this new species is the male cheliped carpus with spur, which is unique for the genus. Apart from that, Apseudopsis arguinensis from Mauritania is different from Apseudopsis rogi in having hyposphenia on female pereonite 2 and 6 and six ventral spines on the pereopod 1 propodus. Apseudopsis isochelatus , also from Mauritania, differs from A. rogi in having lateral invaginations and hyposphenia in all pereonites, a more slender cheliped basis, carpus and chela in males, presence of a dorsodistal spine on the merus and five ventral spines on pereopod 1 propodus, and absence of anteroproximal protuberance with setae on pereopod 2.

Other Atlantic and Mediterranean species of Apseudopsis are very similar to A. rogi in having a pointed rostrum with rounded shoulders and four ventral spines on pereopod 1 propodus, but differ in other relevant characters: A. adami , from the northwestern Iberian Peninsula has posterolateral apophysis on pereonites 2–5 that are absent on A. rogi and ten instead of nine segments on the antennular inner flagellum in mature specimens; A. mediterraneus (Băcescu, 1961) has posterolateral apophyses on pereonites 1–6, hyposphenia on pereonites 2 and 6 and a maximum of eight segments on the antennal main flagellum; A. bacescui (Guţu, 2002) , from the Mediterranean Sea, has posterolateral apophyses on pereonites 1–6, hyposphenians on pereonites 2, 3 and 6 and a maximum of seven segments on the antennal main flagellum. Apseudopsis ostroumovi Băcescu & Cărăuşu, 1947 , from the Black Sea, has posterolateral apophyses on pereonites 1–6, hyposphenia on pereonites 2–6 and a maximum of eight segments on the antennal main flagellum.

A summary of these and other characters distinguishing species of Apseudopsis are given in the key, below.

With regard to observed sex ratios and female fecundity, in sample LE4, the male: female ratio was 4: 6. All males were male II stage, and no copulatory females were found. By contrast, in sample LC4 the male: female ratio was 8: 4, and the four females were copulatory, with a fecundity of 6–8 embryos.

Figures

FIGURE 2. Apseudopsis rogi sp. nov. male II paratype MNCN 20.04 / 10185. A, habitus; B, last pleonites and pleotelson; C, antennule; D, antenna.

FIGURE 3. Apseudopsis rogi sp. nov. male II paratype MNCN 20.04 / 10186. A, right mandible; B, right molar; C, left mandible incisor, lacinia mobilis and setal row; D, maxillule; E, maxillule palp; F, maxilla; G, maxilliped palp; H, maxilliped endite.

FIGURE 4. Apseudopsis rogi sp. nov. A, male II paratype MNCN 20.04 / 10185 cheliped, with detail of the chela; B, exopodite of the same; C, female paratype MNCN 20.04 / 10188 cheliped.

FIGURE 5. Apseudopsis rogi sp. nov. male II paratype MNCN 20.04 / 10185. A, pereopod 1; B, pereopod 2; C, pereopod 3; D, pereopod 4; E, pereopod 5; F, pereopod 6; G, pleopod 5.