Apseudes Leach, 1814

Błażewicz-Paszkowycz, Magdalena, Bamber, Roger N. & Cunha, Marina R., 2011, Apseudomorph tanaidaceans (Crustacea: Peracarida) from mud-volcanoes in the Gulf of Cadiz (North-east Atlantic), Zootaxa 2919, pp. 1-36 : 2-7

publication ID	https://doi.org/ 10.5281/zenodo.277889
DOI	https://doi.org/10.5281/zenodo.6195544
persistent identifier	https://treatment.plazi.org/id/03B187D2-6A1C-FFB6-FF2E-4C336AB4F827
treatment provided by	Plazi
scientific name	Apseudes Leach, 1814
status

Treatment

Genus Apseudes Leach, 1814 View in CoL

Apseudes setiferus B ă cescu, 1981 ( Figs 1–4 View FIGURE 1 View FIGURE 2 View FIGURE 3 View FIGURE 4 )

Apseudes setiferus Bäcescu, 1981: 51 View in CoL –55, fig. 8.

Material examined. 1Ƥ with oostegites, neotype ( BMNH.2010.432), 13 ( BMNH.2010.43), 1Ƥ with oostegites, 13, 2 juveniles ( BMNH.2010.434–437), 1Ƥ with oostegites, dissected, Cruise TTR11, Station AT339, NW of Ibérico, Formosa Ridge, 36°07.765'N, 07°46.461'W, 1086 m depth, carbonate chimneys, geology dredge, 26.08.2001. 1 juvenile ( BMNH.2010.438), Cruise TTR15, Station AT575, Mercator mud volcano, 35°17.903'N 06°38.715'W, 355 m depth, mud breccia, boxcore, 26.07.2005. All coll. MRC.

Other GoC records. 3 specimens, Cruise TTR11, Station AT338, Lolita, Formosa Ridge, 36°08.585'N, 08°00.175'W, 1340 m depth, surrounding hemipelagic mud, gravity core, 25.08.2001; 2 specimens, Cruise TTR12, Station AT407, Pen Duick Escarpment, 35°17.695'N, 06°47.082'W, 560 m depth, dead scleractinean framework, TVgrab, 15.07.2002; 1 specimen, Station AT416, TTR mud volcano, 35°21.87'N 06°52.00'W, 695 m depth, mud and corals, TV-grab, 17.07.2002; 3 specimens, Cruise TTR14, Station AT528, Kidd mud volcano, 35°25.304'N 06°43.972'W, 489 m depth, mud breccia and H2S, TV-grab, 03.08.2004; 7 specimens, Station AT541, Meknès mud volcano, 34°59.103'N 07°04.435'W, 703 m depth, mud breccia and H2S, TV-grab, 05.08.2004; 2 specimens, Cruise TTR14, Station AT550, West of Gibraltar Straits, 35°42.105'N 06°30.196'W – 35°42.257'N 06°30.000'W, 368–392 m depth, carbonate chimneys, geology dredge, 07.08.2004; 1 specimen, Cruise TTR14, Station AT551, West of Gibraltar Straits, 35°42.597'N 06°30.505'W – 35°42.769'N 06°30.305'W, 445 – 393 m depth, carbonate chimneys, geology dredge, 07.08.2004; 1 specimen, Cruise TTR14, Station AT565, Pen Duick Escarpment, 35°18.180'N 06°47.656'W, 544 m depth, coral rubble, TV-grab, 09.08.2004; 3 specimens, Cruise TTR15, Station AT586, Meknès mud volcano, 34°59.146'N 07°04.380'W, 701 m depth, mud breccia, TV-grab, 28.07.2005. All coll. MRC.

Description of female. Body ( Fig. 1 View FIGURE 1 A), dorsoventrally flattened, elongate, neotype female with oostegites 7.2 mm long, seven times as long as wide, narrower posteriorly. Cephalothorax subrectangular, 1.2 times as long as wide, anterior margin with conspicuous pointed triangular rostrum, point downcurved and commonly not visible dorsally. Eyes absent; eyelobes present with prominent spine-like apophyses directed anteriorly; no lateral spiniform apophyses. Six free pereonites; pereonite 1 shortest, one-third as long as cephalothorax, laterally convex with few posterolateral plumose setae; pereonites 2 to 6 with anterolateral spine-like apophyses bearing tufts of plumose setae extending onto dorsal surface, and expanded posterolaterally at attachment of coxae again with tufts of plumose setae; pereonites 3 to 5 with midlateral invagination; pereonites 2 and 6 subequal in length, about 1.25 times as long as pereonite 1; pereonites 3 and 5 subequal in length, 1.4 times as long as pereonite 1; pereonite 4 longest, 1.75 times as long as pereonite 1 (all pereonites respectively 2.4, 1.7, 1.5, 1.1, 1.3 and 1.5 times as wide as long); ventral hyposphenia present on pereonites 2 to 6. Pleon three times as long as pereonite 6, of five free subequal pleonites bearing pleopods, plus pleotelson; pleonites about four times as wide as long, laterally expanded by spiniform apophyses bearing four or five plumose setae. Pleotelson long and slender, 0.6 times length of whole pleon, 2.5 times as long as wide, with slight lateral expansions at one-third and two-thirds length, distally extended as a triangular process, with sparse dorsal and lateral plumose setae.

Antennule ( Fig. 3 View FIGURE 3 A) peduncle 4-articled, proximal article elongate, 4.3 times as long as wide, inner margin denticulate, with numerous penicillate setae and fewer simple setae as figured; second article 0.3 times as long as article 1, with numerous penicillate setae and fewer simple setae as figured; third article 0.56 times as long as second, with two inner simple setae; fourth article half as long as third, with two distal setules. Main flagellum of 22 segments, segments 6, 8, 9, 10, 12, 14, 16, 18 and 20 bearing aesthetascs; accessory flagellum of 10 segments.

Antenna ( Fig. 3 View FIGURE 3 B). Proximal peduncle article 0.43 times as long as second article, with inner triangular apophysis bearing three setae; article 2 inner margin with groups of mesial and distal denticulations, and bearing elongate squama with nine simple marginal setae; peduncle article 3 as long as wide, one-quarter as long as article 2, with inner-distal pointed apophysis and adjacent long seta; article 4 three times as long as article 3, inner margin with simple mid-length seta and paired distal penicillate setae; article 5 three-quarters as long as article 4, inner margin with simple mid-length seta and two distal setae, distally with paired inner and outer penicillate setae. Flagellum of 15 segments.

Mouth parts. Labrum with stout, sharp epistome (e.g. Fig. 1 View FIGURE 1 B). Right mandible ( Fig. 2 View FIGURE 2 A, C) bearing strong, crenulated pars incisiva, setiferous lobe with four trifurcate and one simple setae and incisive extension similar to a lacinia mobilis, pars molaris ( Fig. 2 View FIGURE 2 D) elongate with finely denticulate distal margins; mandibular palp ( Fig. 2 View FIGURE 2 E) of three articles, proximal article as long as wide with three inner setae and inner-distal spine-like apophysis, article 2 three times as long as article 1 with group of 12 finely-denticulate setae in distal half; article 3 twice as long as article 1 with 24 inner finely-denticulate setae in four rows and four longer finely-denticulate distal setae. Left mandible ( Fig. 2 View FIGURE 2 B) as right, but with coarsely denticulate lacinia mobilis. Maxillule ( Fig. 2 View FIGURE 2 F) inner endite with outer proximal apophysis, finely setose inner and outer margins and three finely setulate and two simple distal setae; outer endite with eleven distal spines and two subdistal setae, inner and outer margins finely setose; palp ( Fig. 2 View FIGURE 2 F’) of two stout articles, distally with eight setae. Maxilla ( Fig. 2 View FIGURE 2 G) with microtrichial rows on all margins; outer lobe of movable endite with two simple setae on outer margin, distally with two finely-denticulate and six simple setae; inner lobe of movable endite with seven simple and two bilaterally plumose setae; outer lobe of inner endite distally with five outer plumose setae, three trifurcate spines and one inner pinnate seta, and one proximal plumose stout seta; inner lobe of fixed endite with rostral row of 31 setae guarding eight longer distally-denticulate setae. Maxilliped ( Fig. 2 View FIGURE 2 H) basis with two simple distal setae exceeding distal margin of proximal palp article; palp article 1 with single seta on outer margin and longer simple seta on inner margin; palp article 2 longer than wide, with rows of 17 setae on inner margin, outer margin with two slender distal spines; palp article 3 with 13 simple setae in two rows along expanded inner margin; palp article 4 with ten distally-setulose distal setae and one simple subdistal seta. Endite (not figured) with simple inner caudodistal seta. Epignath ( Fig. 2 View FIGURE 2 I) large, cup-shaped, with conspicuous inner lobes and finely-setulose distal seta.

Cheliped ( Fig. 4 View FIGURE 4 A) basis stout, twice as long as wide, dorsally with fine subdistal seta, ventrally with four fine setae in proximal half, stout midventral spine and three distal setae; exopodite present, 3-articled, second article naked, distal article with six plumose setae. Merus elongate, slightly sinuous, narrowing proximally, ventrally with proximal seta and two distal setae surrounding short spine, dorsally with paired distal setae, outer margin with two mesial setae. Carpus three times as long as wide, with seven simple setae in three groups along ventral margin, smaller dorsodistal seta. Chela palm 1.3 times as long as wide, fingers shorter than palm, ventral margin with twelve setae; twelve setae along cutting edge of fixed finger; cutting edge ( Fig. 4 View FIGURE 4 A’) distally with seven tooth-like spines, proximally with slight inner apophysis bearing tuft of setae; dactylus with three setae but no apophyses on cutting edge, distal claw pointed.

Pereopods: Pereopod 1 ( Fig. 3 View FIGURE 3 C) coxa with prominent spine-like apophysis (vide Fig. 1 View FIGURE 1 B), basis 3.7 times as long as wide, with sparse setae along dorsal and ventral setae, longest proximally, small dorsoproximal spine, ventrodistally with short spine and two setae; exopodite present, 3-articled, article 3 with five distal plumose setae. Ischium with three simple ventrodistal setae. Merus just over half as long as basis, with mesial tuft of seven setae, ventrodistal spine, slender dorsodistal spine and two dorsodistal simple setae. Carpus 0.8 times as long as merus, with dorsodistal spine in tuft of six setae, ventrally with two spines and four setae. Propodus shorter than merus, with four ventral and two dorsal spines interspersed with setae. Dactylus stout, with three mid-dorsal fine setae and four ventral denticulations; unguis short; both together as long as propodus.

Pereopod 2 ( Fig. 4 View FIGURE 4 B) more slender than pereopod 1. Basis 5.4 times as long as wide, margins sparsely setose with proximal penicillate setae, three ventrodistal setae. Ischium with two ventrodistal and one dorsodistal setae. Merus 0.8 times as long as carpus, with four ventral setae and ventrodistal spine, three dorsodistal setae. Carpus elongate, with setae along ventral margin and slender ventrodistal spine, tuft of six dorsodistal setae on rounded apophysis. Propodus slightly longer than carpus, with four ventral setae interspersed with three finely-denticulate spines, dorsally with distal finely-denticulate spine and subdistal tuft of five setae. Dactylus slender with two ventral denticulations, unguis slender, 0.4 times as long as dactylus, the two together 0.74 times as long as propodus.

Pereopod 3 ( Fig. 4 View FIGURE 4 C) similar to pereopod 2, but carpus with mid-ventral rather than ventrodistal spine, propodus with three dorsodistal spines and two short spines on inner face, dactylus with three ventral denticulations.

Pereopod 4 ( Fig. 4 View FIGURE 4 D) basis 4.9 times as long as wide, with two dorsoproximal penicillate setae, one ventral subdistal penicillate seta and one ventrodistal seta. Ischium with two ventrodistal setae. Merus half as long as carpus, with five ventral setae and shorter mid-ventral and two ventrodistal spines, one dorsodistal seta. Carpus elongate, with four spines along ventral margin in two pairs, five ventrodistal spines, and distal crown of setae. Propodus slightly shorter than carpus, with dorsoproximal penicillate seta, six fine ventral spines, distally with crown of finely setulose and (dorsally) simple setae; dactylus and unguis together 0.4 times as long as propodus.

Pereopod 5 ( Fig. 4 View FIGURE 4 E) similar to pereopod 3, but propodus with short row of leaf-like spines in distal half.

Pereopod 6 ( Fig. 4 View FIGURE 4 F) coxa, basis, ischium, merus and carpus with plumose setae as figured; propodus with rows of leaf-like spines along distal half of ventral margin and around distal margin; dactylus and unguis together 0.84 times as long as propodus.

Pleopods ( Fig. 4 View FIGURE 4 G) all alike. Basis elongate, with three ventral plumose setae. Exopod shorter than endopod; both rami slender, with about 15 marginal plumose setae. Outer proximal seta on exopod separated from remaining setae.

Uropod ( Fig. 4 View FIGURE 4 H) biramous, both rami filiform, multi-segmented. Basis with six outer and one inner setae distally; exopod less than half as long as endopod, with ten segments; endopod elongate, more than twice as long as pleotelson, with about 33 segments.

Distinctions of male. ( Fig. 1 View FIGURE 1 B) Generally as female, antennular aesthetascs slightly more numerous, pereonite six with penial tubercle.

Remarks. Bäcescu (1981) described this species originally from a single female taken off the Bay of Biscay (47°43.1'N, 08°04.0'W) at 1035–1080 m depth on mud, but that description (and specimen) was somewhat incomplete; the present material has allowed us to describe the species fully, including the male. As the original typematerial can no longer be found, we have designated a female from the present material as a neotype.

Slight differences observed between our material and the type description are that Bäcescu (1981) shows the sixth pereonite to be twice as long as pereonite 2, while in the present material these two pereonites are subequal in length; the present material also shows more setae on the cheliped, although whether that is a difference in the material or in the attention to detail is unclear.

With the prominent coxa 1 apophysis, row of leaf-like spines on the propodi of pereopods 5 and 6, and denticulate outer margin on the antennular peduncle, Apseudes setiferus accords with the restricted diagnosis of Apseudes given by Guţu (2006). The present species is morphologically closest to the generotype A. talpa ( Montagu, 1808) in terms of the proportions of the cephalothorax and pleotelson, conformation of the rostrum, pereonites and pleonites, and the presence of hyposphenia, but has one more ventral propodal spine on pereopod 1, and most notably far more segments in the flagella of the antennule and antenna – A. talpa has an antennule with 11 segments in the main flagellum and five in the accessory flagellum, and an antennal flagellum with eight segments, compared with 22, 10 and 15 segments respectively in the new species. A. talpa is found in the north-east Atlantic at a depth range of 0 to 33 m on algal-associated and heterogeneous substrata, while A. setiferus has now been recorded from depths of 355 to 1340 m, and always from muddy substrata. Unlike A. talpa , the present species is not a simultaneous hermaphrodite, specimens with oostegites never having a penial tubercle (and vice versa).

The “pseudo-lacinia mobilis” on the right mandible is an unusual feature of Apseudes setiferus .