Anaspides Thomson, 1894

Ahyong, Shane T., 2016, The Tasmanian Mountain Shrimps, Anaspides Thomson, 1894 (Crustacea, Syncarida, Anaspididae), Records of the Australian Museum 68 (7), pp. 313-364 : 315-316

Anaspides Thomson, 1894

Anaspis Thomson, 1893: 7 (preoccupied, Anaspis Geoffroy, 1762 [ Coleoptera ]; type species: Anaspis tasmaniae Thomson, 1893 ).

Anaspides Thomson, 1894: 285 , 286 (replacement name for Anaspis Thomson, 1893 , preoccupied).

Diagnosis. Rostrum prominent, well-developed. Cephalothorax without fenestra dorsalis. Body subcylindrical, straight or evenly curved, without prominent “bump-like” flexure at pleonite 1. Free pereonites length subequal, shorter than pleonites. Pleonite 6 shorter than twice length of pleonite 5; surface of integument with few setae but no spines. Telson dorsoventrally compressed; posterior margin rounded or angular, with spine row. Antennular and antennal peduncles unarmed. Scaphocerite with small lateral spine. Thoracopod 1 (maxilliped) with epipods. Thoracopod 7 with exopod. Uropodal endopod more than three-fourths length of exopod; exopod with small group of movable spines near position of diaraesis.

Description. Body subcylindrical, straight or evenly curved, without prominent “bump-like” flexure at pleonite 1. Rostrum prominent, apex blunt, rounded, slightly deflected ventrally; few distal setae, arising submarginally. Head (cephalothorax) comprised of fused cephalon and pereonite 1; cervical groove distinct; dorsal organ present on dorsal midline anterior to cervical groove; mid-lateral surface posterior to cervical groove with shallow diagonal groove. Pereonites 2–8 length subequal, subparallel, shorter than pleonites. Pleonites 1–5 length subequal; subparallel; pleura well-developed, rounded. Pleonite 6 shorter than twice length of pleonite 5; surface of integument with few setae but no spines. Telson dorsoventrally compressed, with low, broad median ridge; posterior margin rounded or angular, with spine row; surface with low, broad median crest, few scattered setae. Female gonopore (spermatheca) on pereonite 8 sternum between coxae; bulbous, directed anteriorly, anterior surface with genital orifice as narrow transverse slit. Pleonal sternites 3–5 with low median processes between pleopod bases.

Eyes pedunculate; cornea usually well-developed.

Antennular peduncle 3-articulate, unarmed; article 1 with statocyst; biflagellate, inner (= accessory) flagellum shorter than outer; adult males with proximal portion of inner flagellum modified to form clasping structure, with proximal 8 articles bearing dorsal finger setae and together semi-rigid, S-shaped, curled, strongly curved downward, then turning upwards and horizontally in vicinity of articles 5 and 6, with slender clasping spines on obtusely angled inner margin of article 7.

Antenna uniflagellate; protopod 3-articulate, unarmed; exopod (scaphocerite) laminar, broadly ovate, small lateral spine, mesial and distal margin setose to base of lateral spine; endopod peduncle 2-articlulate, unarmed.

Labrum with shallow proximal constriction, anterior proximal surface with blunt median ridge; distal margin convex to slightly concave, finely setose.

Mandibular corpus (apophysis) robust; molar process and incisor process well-developed; molar with elongate, ovate, triturating surface, surrounded by spiniform setae; incisor process diagonal to axis of mandibular corpus; left incisor process with 7 triangular teeth in sinuous row, proximally with spine row between proximal incisor tooth and molar process; right incisor process similar to left except with 6 triangular teeth, proximal tooth usually apically divided; palp 3-articulate, setose, article 1 short, subquadrate, article 2 slender, almost twice length of article 3.

Paragnaths widely separated by deep V-shaped incision, without lobes, distal half finely setose, especially mesially.

Maxillule with 2 endites; proximal endite distally setose; distal endite spinose distally, lateral surface with small rounded palp.

Maxilla with 4 endites, proximal 2 endites with plumose setae, distal 2 endites densely arrayed with serrulate setae.

Thoracopods 1–8 protopod with coxa, basis, preischium, ischium, merus, carpus, propodus and dactylus; flexure at carpus-merus articulation.

Thoracopod 1 (maxilliped) coxa inner margin with setose coxal endites, outer margin with 2 slender, lamellar epipods, proximal wider than distal; basis with slender, flattened, strap-like exopod; coxa-basis demarcation often ill-defined; preischium rectangular, more than twice length of quadrate ischium; merus as long as preischium, slightly tapering distally; carpus triangular, longer than high, half length of merus; propodus slender, slightly shorter than merus; dactylus short, terminating in slender claw, with 2 slender movable spines on lateral side, 3 on mesial side.

Thoracopods 2–8 (pereopods) as ambulatory legs. Thoracopods 2–6 structurally similar, distal 4 articles with tufts of setae, primarily along flexor margins, dactylus strongly setose; thoracopods 4–5 longest; coxa outer margin with 2 ovate, lamelliform epipods, inner margin in adult females with setose endite; basis short, partially fused with preischium; exopod articulating with outer margin of basis, with elongate basal article and setose multi-annulate flagellum (<30); ischium about as long as basis-preischium; merus elongate, slightly tapering distally, about twice length of ischium; carpus triangular, longer than high, about half length of merus or slightly less; propodus elongate, slender, shorter than merus; dactylus short, terminating in long, slender claw, with slender movable spine on lateral side, 2 movable spines on mesial side. Thoracopod 7 similar to thoracopods 2–6 except epipods proportionally more slender; exopod a single narrow lamella. Thoracopod 8 structurally similar to preceding thoracopods but lacking epipods or exopod; basis and preischium indistinguishably fused; longer than thoracopod 7.

Pleopods 1–5 exopod long, slender, setose, 25–30- annulate. Pleopods 1–2 endopod always present, unmodified endopod ovate, lamellar, length subequal to first exopod article, variously present on pleopods 3–5 in females and juvenile males; adult male pleopods 1–2 endopod modified as copulatory structures (petasma). Adult male pleopod 1 elongate, directed anteriorly, reaching beyond thoracopod 8 coxa; slender proximally, expanded distally forming cannulate, scoop-like structure, hollowed mesially; distally rounded, lateral margin thin, lamellate; inner margin with short row of retinaculae near distal one-third, forming small rounded lobe; inner proximal surface with scattered setae and spinules. Male pleopod 2 endopod of 2 articles, longer than that of pleopod 1, directed anteriorly, reaching to thoracopod 8 coxa; proximal article twice length of distal article, mesial proximal margin with row of retinaculae; distal article broadly curved, mesially hollowed, apex blunt.

Telson and uropods forming tail-fan. Uropodal exopod lateral margin with indistinct, partial diaeresis near distal one-third; movable spines near position of diaeresis, flanked by tufts of setae; inner margin and outer margin distal to diaeresis setose. Uropodal endopod slightly shorter than exopod, margins setose.

Species composition. Anaspides clarkei Ahyong, 2015 , A. eberhardi sp. nov., A. jarmani Ahyong, 2015 , A. richardsoni sp. nov., A. spinulae Williams, 1965a , A. swaini Ahyong, 2015 , A. tasmaniae ( Thomson, 1893) (type species).

Remarks. Anaspides is one of three anaspidid genera endemic to Tasmania, others being Paranaspides Smith, 1908 (with only the type species, Paranaspides lacustris Smith, 1908 ), and Allanaspides Swain, Wilson, Hickman & Ong, 1970 (with the type species A. helonomus Swain, Wilson, Hickman & Ong, 1970 , and A. hickmani Swain, Wilson & Ong, 1971 ) ( Lake et al., 2002). Allanaspides , which uniquely has a fenestra dorsalis on the cephalothorax, lacks maxillipedal epipods and lacks the exopod on thoracopod 7, is believed to be sister to other anaspidids (Jarman & Elliott, 2000). Paranaspides is most closely related to Anaspides , being sister to, or possibly nested within, the latter (Jarman & Elliott, 2000). Few major features separate the two genera, however. Paranaspides , with a pelagic rather than benthic habit, is considerably more spinose than Anaspides but the most important distinguishing feature is the distinct pleonal flexure of the former as a result of the wedge-shaped pleonite 1.

Phylogenetic relationships inferred from mitochondrial 16S sequences from selected Anaspides populations (Jarman & Elliott, 2000; Andrew, 2005), although with low resolution, recognized three broad clades: a southern group corresponding to A. jarmani and A. clarkei , which diverged from other Anaspides approximately 25 ma; a southwestern group ( A. swaini ); and a northern-eastern group corresponding here to A. tasmaniae , A. spinulae , A.richardsoni and A. eberhardi ).

The phylogenetic significance of Anaspides for Malacostraca has prompted numerous morphological, ultrastructural and physiological studies, all under the name A. tasmaniae . Those applicable to A. tasmaniae sensu stricto are as follows: embryology ( Hickman, 1937); giant lateral neurone (Silvey & Wilson, 1979); organ of Bellonci (Kauri & Lake, 1972); locomotory function ( Macmillan et al., 1981); spermogenesis ( Jespersen, 1983); foregut morphology ( Wallis & Macmillan, 1998); and ommatidial structure ( Richter, 1999); and cuticular sclerites ( Kutschera et al., 2015). Manton’s (1930) study of habits and feeding are based on A. tasmaniae and A. swaini . Studies of functional morphology and excretion (Cannon & Manton, 1927; Manton, 1929, 1931) are probably based on A. swaini given the photograph by Sidnie Manton, presented by William Calman to the Royal Zoological Society of London depicting what appears to be A. swaini ( MacBride, 1930) . Analyses of ecology and life history (Swain & Reid, 1983) and mandibular morphology ( Richter et al., 2002) are based on A. richardsoni from Mt Field. Serov (1988) examined ecology of populations from Browns River near Silver Falls, which are thus referable to A. tasmaniae . Specimens studied by Tjønneland et al. (1984) for heart ultrastructure, from Myrtle Forest Creek, are referrable to A. swaini . Smith’s (1908, 1909b) studies of general morphology may be based several species given that he accessed material from Mt Wellington (North West Bay River), Mt Field and the Hartz Mountains, localities at which A. swaini , A. richardsoni and A. jarmani occur, respectively. Internal anatomy (gonads and alimentary canal) reported by Nicholls & Spargo (1932) is probably based on A. richardsoni given that Nicholls collected widely in the Great Lake area, many specimens of which are still extant in the collections of the Western Australian Museum and Tasmanian Museum. Specimens of Anaspides collected by Smith were the source material for a parasitic protozoan, Ganymedes anaspidis described by Huxley (1910). Given the uncertainty over the identity of Smith’s Anaspides specimens, however, the host species of the type material of G. anaspidis likewise remains unclear.

Anaspides tasmaniae was originally described as the type species of Anaspis Thomson, 1893 . Anaspis Thomson, 1893 , however, being preoccupied by Anaspis Geoffroy, 1762 (Coleoptera) , was replaced by Anaspides Thomson, 1894 . Seven species of Anaspides are recognized here of which two are new to science.