Apseudes talpa Montagu 1808
Creators: name: Larsen, Kim
name: Bertocci, Iacopo
name: Froufe, Elsa
Publisher: name: Zenodo
Year: 2011
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Tanaidacea
Apseudidae
Apseudes
Apseudes talpa

description: Apseudes talpa (Montagu, 1808)
(Figs 1–7)
Diagnosis (simultaneous hermaphrodite/male): Body without hyposphenia except for conspicuous penal cone on the 6th pereonite. Body with several, pleon with many, mostly lateral, setulose setae. Pleon also with many dorsal setulated setae. Pleonites wider than long and with blunt lateral epimera. Antenna with well-developed squama with simple setae. Maxilliped basis with serration on laterodistal corners; palp article 2 with one outer spiniform setae. Cheliped merus with ventral spine and two inner ventral spiniform setae; carpus shorter than in female/juvenile and with ventral spines; fixed finger as long as dactylus, with inner process. Pereopod 1 dactylus without serration. Pleopod rami uniarticulated. Uropod endopod with at least 15 articles.
Non-ovigerous female/juveniles (where differing from male/hermaphrodite): pereonite 6 without- or with only anlagen to- penal cone; cheliped carpus longer than in male and without spines; chela fixed finger without process.
Material examined. Syntype: Syntype material, 4 simultaneous hermaphrodites, 1 non-ovigerous male, 1 nonovigerous female, and 1 indeterminable sex (fragments), all in a bad condition (BMNH 1950.8.5.6-8 and BMNH 1975º.275.4) from Salcombe, Devon. Additional UK material, 1 simultaneous hermaphrodite and 1 manca, from Burnt Island, Periglis Cove, St Agnes, Isles of Scilly, UK (49º53.77'N 06º21.71'W), 9 September 2010. Portuguese material: 1 ovigerous hermaphrodite (reg # MMF 41154-1) 5.8 mm. 1 m depth from algae, particularly kelp holdfasts. 1 ovigerous hermaphrodite (5.2 mm), same locality (dissected) (reg # MMF 41156-3). 1 small female (3.1 mm) without male- or hermaphroditic characters (reg # MMF 41155-2). 12 males (or non-ovigerous hermaphrodites), 7 ovigerous hermaphrodites, 21 small females (or juveiles), + 50 mancae. Same locality (MMF 41157-4). 1 ovigerous hermaphrodite, 2 small females (or neuters), 3 mancae.
Description. Body and appendages from ovigerous hermaphrodite (Mindelo, Portugal). Body and mandibles also from ovigerous hermaphrodite syntype (1950.8.5.6.8), Devon, UK and ovigerous hermaphrodite Isles of Scilly, UK.
Body (Figs. 1 A, B, 2A, 6A, B). Dorsoventrally flattened, about 4.7 times as long as wide.
Cephalothorax. As long as pereonites 1–3 combined (including rostrum). Eyes well developed and separated from carapace by a groove, with few (seven to nine) visual elements, ocular lobes with minuscule apophysis. Rostrum blunt and triangular in dorsal view but bent ventrally and pointed in lateral view. Carapace spines absent anterior of the respiratory chamber but anterolateral plumose setae present.
Pereonites. All with lateral setation consisting of plumose setae, setation more prominent on posterior pereonites. All pereonites wider than long. Pereonites 3–5 with one small anterolateral blunt spine. Lateral shoulders prominent on all pereonites.
Pleon. Less than 30% of total body length. Pleonites (Fig. 2 B) all wider than long, with weakly pointed epimera bearing dorsal and lateral setae. All pleonites with pleopods but no ventral keel. Pleotelson as long as four last pleonites combined (not visible in dorsal view owing to body curvature).
Antennule (Fig. 2 C). As long as carapace. Peduncle article 1 less than half as long as rest of antennule, with several spines along inner margin and medial cluster of simple setae; with several small setulose setae and few simple setae on outer margin. Article 2 more than twice as long as article 3, with several simple and setulose distal setae. Article 3 with three simple distal setae. Article 4 (common article) two distal setae on inner margin. Outer flagellum as long as first peduncle article, of 11 articles, 8 and 10 with aesthetascs. Inner flagellum longer than half of outer flagellum and of six articles.
Antenna (Fig. 2 C). With about 14 articles. More than half as long as antennule. Article 1 without apophysis. Article 2 with few simple setae and four spines. Squama attached distally on article 2 reaching beyond end of article 3, with nine simple setae. Article 3 much shorter than 4 and 5. Articles 4 and 5 rectangular with several simple and two setulose setae each. Articles 6–14 (flagellum) serially repeating with simple setae.
Mouthparts. Labrum (Fig. 3 A) articulated from clypeus, distal margin finely setulose and rising slightly at midlenght. Basal part with weakly setulose lobe on upper side and with two lateral ridges on lower side. Mandibles molar process with denticulate apex. Mandibular body with semicircular ring of blunt denticles along the outer side (the side of the palp). Additional small spines/tubercles on the dorsodistal corner near incisor. Palp long (almost as long as mandibular body), with three articles; article 1 with four setae; article 2 with distal row of pinnate setae; article 3 with mediodistal row of pinnate setae. Left mandible (Figs. 3 B, 7A,C–E) setal row of five multifurcate setae; incisor with five denticles, lacinia mobilis with three denticles. Right mandible (Figs. 3 C, 7B) incisor with four denticles; setal row consisting of five complex setae arising from common peduncle. Labium (Fig. 3 D) palp with numerous setules and three simple terminal setae. Lobes almost naked. Maxillule (Fig. 3 E) palp with two articles, distal article with weak terminal serration and five terminally serrated long setae. Outer endite with eight spiniform distal setae and scattered setae/setules; inner endite with four setulose distal setae and setules on both margins. Maxilla (Fig. 3 F) outer lobe of movable endite with two outer and five inner, distal, long, distally serrated, proximally setulose, setae, but no spines on outer margin. Inner lobe of movable endite with row of five simple and five pinnate setae as well as scattered setules. Outer lobe of fixed endite with four simple/serrated, three multifurcate spiniform setae, one circumplumose spiniform seta, one double serrated subdistal seta, and outer setules. Inner lobe of fixed endite with row of numerous distally curved setae and five robust, distally serrated, setae separated by large gaps. Inner basal margin with small spines. Maxilliped (Fig. 3 G) coxa naked. Basis with spines on outer distal corner and four long setae on inner distal corner. Endite with three robust but apparently simple setae on distal margin; inner margin with three coupling hooks and row of ten circumplumose setae; outer margin with fine setules. Palp article 1 with three simple setae on inner margin; article 2 with row of simple setae on inner margin and strong spine distally on outer margin; article 3 with rows of simple setae on inner margin; article 4 with three pinnate- and multiple simple distal setae. Epignath (Fig. 3 H) Basal process weakly setulose, rest of body naked, terminal seta short and circumplumose.
Cheliped (Fig. 4 A). Exopod distal article with six plumose setae. Basis marginally shorter than carpus with cluster of ventrodistal setae and one prominent ventromedial spine. Merus longer than half of carpus, with eight ventrodistal setae and strong blunt ventrodistal spine and two additional spiniform setae on the inner side next to spine. Carpus with several ventral setae and two ventral spines; with proximal and distal dorsal setae. Propodus with seta at dactylus insertion and on ventral margin. Fixed finger with rows of setae along ventral margin; cutting surface with distal setae and proximal process. Dactylus as long as fixed finger, with weak proximal depression and two subdistal setae.
Pereopod 1 (Fig. 5 A). Longer and wider than other pereopods. Exopod distal article with seven plumose setae. Coxa with prominent apophysis and several plumose setae and small oostegite. Basis about as long as merus and carpus combined, with scattered ventral and dorsal setae and cluster of ventrodistal setae. Ischium with cluster of ventral setae. Merus longer than carpus, with scattered ventral and medial simple setae and one spiniform seta on each distal corner, dorsodistally with cluster of simple setae. Carpus as long as propodus, with one dorsal, one small distal, and two ventral spiniform setae and scattered simple setae. Propodus as long as dactylus/unguis, with three ventral and two dorsal spiniform setae and scattered simple setae. Dactylus 0.65 times as long as propodus, without serrations and two dorsal setae. Unguis one third as long as dactylus.
Pereopod 2 (Fig. 5 B). Coxa with two plumose setae and small oostegite. Basis longer than ischium, merus and carpus combined; with few setae on both margins and cluster of ventrodistal setae. Ischium with simple distal setae. Merus as long as carpus, with one ventral spiniform seta and five simple ventral setae, dorsally with one spiniform seta and cluster of distal setae. Carpus shorter than propodus, with two ventral and dorsodistal cluster of simple setae, with tow unequal spiniform ventral setae. Propodus with three ventral, one dorsal spiniform setae, additional mediodistal spiniform serrated seta (comb seta) near dactylus insertion, three ventral simple setae and cluster of dorsodistal setae. Dactylus with two simple dorsomedial setae. Dactylus and unguis combined shorter than propodus.
Pereopod 3 (Fig. 5 C). Coxa to ischium as pereopod 2. Merus and carpus with only one spiniform seta.
Pereopod 4 (Fig. 5 D, D1). Coxa with five plumose setae and small oostegite. Basis longer than ischium, merus and carpus combined; with two plumose and two setulated dorsal setae and ventrally with three simple subdistal and distal clusters of simple setae. Ischium with simple distal setae. Merus shorter than carpus, with three ventral spiniform setae and scattered simple ventral setae, dorsally with one simple seta. Carpus longer than propodus, with six spiniform setae and scattered simple setae. Propodus with two ventral spiniform setae, two long distal simple setae, and row of distal spiniform setae, three ventral simple setae, dorsally with one setulated seta proximally. Dactylus with two small ventral serrations. Dactylus and unguis reduced compared with those of other pereopods.
Pereopod 5 (Fig. 5 E). Basis with row of plumose dorsal setae and two long dorsal plumose setae, few simple scattered setae and cluster of ventrodistal setae, shorter than combined length of ischium–carpus. Ischium with cluster of ventrodistal setae. Merus shorter than carpus, with four small ventral and one long dorsal spiniform setae and scattered simple setae. Carpus with six spiniform and scattered simple setae ventrally, dorsally with row of plumose setae. Propodus with few distal simple setae, lateral row of five spiniform setae, and ventral row of one large and multiple small spiniform setae. Dactylus with single serration and two dorsal simple setae. Dactylus and unguis not reduced compared to other pereopods
Pereopod 6 (Fig. 5 F). Basis, merus and carpus densely covered with plumose setae on both margins. Ischium with two ventral and one dorsal plumose setae. Carpus with two ventral spiniform setae. Propodus without plumose setae, with ventral row of identically repeating small spiniform setae as well as proximal and distal larger spiniform setae. Dactylus not serrated, with two dorsal simple setae.
Pleopods (Fig. 2 D). Peduncle uniarticulated, with four plumose setae (setae less densely plumose than those on rami) arising from projection on inner margin. Exopod uniarticulated, with about 28–29 plumose setae (not all drawn). Endopod longer than exopod, with about 23–26 plumose setae (number varying between pleopods).
Uropod (Fig. 2 E). About twice as long as pleotelson. Basal article three times as long as wide, several distal setae. Endopod with more than 18 articles, some of which pseudoarticulated, most with one or more distal setae. Exopod with four articles, proximal article smaller and wider than other articles, succeeding three articles each with pseudo-articulations and one to three simple setae.
Small female (where differing from male/hermaphrodite)
Body. Pereonite 6 without genital cone.
Cheliped (Fig. 4 B): as in male/hermaphrodite except: merus with one ventral spine and only one spiniform inner seta. Carpus without spines, longer and thinner than that of male/hermaphrodite. Propodus more elongated than in male/hermaphrodite. Fixed finger without inner process and dactylus without proximal depression.
Remarks. The older/larger specimens are all simultaneous hermaphrodites but this condition seems to be restricted only to large specimens, although it was not possible to determine whether the ‘non-ovigerous males’ are really ‘males’ or just non-ovigerous hermaphrodites. Neither was it possible to determine whether the small ‘females’ are really ‘females’ or just sexually immature hermaphrodites. The question of simultaneous hermaphrodites was first raised by Lang (1953) and has been a focal point of confusion ever since. It is well known that other Tanaidacea can be hermaphroditic (Bückle-Ramirez 1965, Gardiner 1975) but this condition was thought to be due to sex change (Sieg 1983) and not a simultaneous condition.
Unfortunately the syntypes of A. talpa were all in a very bad condition that did not allow for useful illustrations. It was, however, possible to verify the presence of the mandibular ridge, the presence of simultaneous hermaphrodites, and the general habitus proportions.
Care must be taken when observing for the ring of blunt denticles on the mandibular body, since it is only visible when the palp side faces upwards, otherwise the solid mandibular body will obscure the view of the character.
The redescription (illustrations) of A. talpa from Mauritania (Guţu 2006:55–56) is here considered as not A. talpa and should probably be raised to species rank, but would need a full description of all appendages first.
description: Published as part of Larsen, Kim, Bertocci, Iacopo & Froufe, Elsa, 2011, Apseudes talpa revisited (Crustacea; Tanaidacea). The impact on apseudidaen systematics, pp. 19-30 in Zootaxa 2886 on pages 20-26, DOI: 10.5281/zenodo.277609