Paronesimoides voightae Larsen 2007, n. sp.
Creators: name: Larsen, Kim
Publisher: name: Zenodo
Year: 2007
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Amphipoda
Lysianassidae
Paronesimoides
Paronesimoides voightae

description: Paronesimoides voightae n. sp.   
(Figs. 1–3).  
 Material examined. Holotype, ovigerous female, 5.2 mm. (FMNH # 13756), Station code VOIJALV4046F, Dive 4046, near Wuzza Bare Mount, 3 September, 2004; 47°47.09’ N 127°41.443’ E. Depth 2656 m. Paratypes: 1 male, 4.1 mm. (KMNH IvR 700248), 1 male (dissected). 3 sex? 1.3 -2 mm, (FMNH # 12848). 1 ovigerous female, 1 male, 7 sex? 1.8–4.5 mm, (FMNH # 12895). 1 male 2.8 mm, 3 sex? 1.8–2.2 mm, (FMNH # 12899). 1 ovigerous female 4.9 mm, (dissected), 1 sex? 2.2 mm, (FMNH # 12906). 2 specimens, (FMNH # 12932). 2 males, 1 ovigerous female, 3 sex? 2.4–4.7 mm. 1 ovigerous female, (FMNH # 12987). 1 ovigerous female, 5.3 mm, (FMNH # 13022). 1 ovigerous female, 4.7 mm (dissected), 2 males 4.4–4.7 mm, (FMNH # 13027).   
 Diagnosis. Antenna 2 with large spiniform process on article 3. Coxa 1 posteroventral margin almost completely covered by coxa 2. Epimeron 3 with tiny posteroventral tooth. Maxilliped palp stout. Gnathopod 2 propodus rectangular. Telson distal margin smoothly rounded.   
 Etymology. Named after the expedition leader Dr. Janet R. Voight.   
 Description. Holotype, female 5.2 mm (only outward appearance of body); paratypes, female 4.7 and 4.9 mm (appendages).   
 Body (Fig. 1A). Rostrum lacking. Eyes absent. Lateral cephalic lobe prominent and acute, subantennular sinus concave. Body smooth, without posterior dorsal carinations. Epimeron 1 anterior margin tapering in posteroventral direction. Epimeron 2 subrectangular, corners rounded, anterior margin slightly concave. Epimeron 3 larger, trapezoid, with large posterior sinus and small posteroventral tooth. Urosomite 1 without depression.   
 Coxae (Figs. 1A, 3 AB, 2C–G). Coxa 1 (Fig. 3A) posterior and distal margin smoothly curved but mostly hidden by coxa 2; posteroventral margin only visible in straightened specimens, with small distal indentation, w/d ratio 0.8. Coxa 2 (Fig. 3B) rectangular with small indentation at posteroventral corner, w/d ratio 0.5. Coxa 3 (Fig. 2C) of similar shape and size but without indentation, w/d ratio 0.6. Coxa 4 (Fig. 2D) only marginally larger than coxae 2–3, with posterior margin strongly excavated, w/d ratio 0.8. Coxa 5 (Fig. 2E) larger than coxa 6–7, equilobate, w/d ratio 1.3.Coxa 6 (Fig. 2F) posterior lobe smoothly rounded and larger than anterior lobe, w/d ratio 0.9. Coxa 7 smallest, weakly trapetzoid, w/d ratio 1.1.   
 Antenna 1 (Fig. 1B). Shorter than head and pereonites 1–3. Peduncular article 1 about twice as long as article 2, with a slight distal tooth. Peduncular article 2 three times as long as article 3. Flagellum marginally longer than peduncle, with 13–15 articles. Accessory flagellum shorter than peduncle, 6-articulate; first article much shorter than first peduncle article. Second and third articles each less than half the length of first article, succeeding articles progressively shorter. Callynophore very weak.   
 Antenna 2 (Fig. 1C). About as long as antenna 1. Peduncular article 2 with prominent gland cone. Peduncular article 3 shorter than article 4, with long, lateral, distally denticulate process with several setae. Article 4 as long as article 5 but wider. Flagellum with 10–12 articles.   
 Mouthparts. Epistome-labral complex (Fig. 1D): upper lip almost completely fused with epistome, with setose slightly lobed apex. Mandibles (Fig. 1E, 1F) incisor (Fig. 1E1) well developed, with one denticle; spine row (Fig. 1E 1, 1E 2) with 3 bifurcate spiniform setae. Molar fairly broad, with dorsal projection, weakly triturative, setose. Palp 3-articulate, attached level with molar, article 1 very short, naked; article 2 1.25 times as long as article 3, with 6 posteroventral D2 setae; article 3 falciform, with 10 D3 setae, with 1 E3 seta, without A3-seta but with scattered setules. Lacinia mobilis in the shape of a blunt bifurcate peg-like spine, on left mandible only. Lower lip (Fig. 1G) outer lobes with distal curved process heavily setose along apical margin. Mandibular processes rather weak and tapering. Maxilla 1 (Fig 1H): inner plate slender, with 1 setulose and 1 or 2 small simple apical setae. Outer plate (Fig. 1H, 1H1) with spine or setal-teeth in 6/5 crown arrangement, STA–STD distally and medially cuspidate, ST1–4 almost smooth, ST5–6 distally and medially cuspidate, ST7 twice as large as other teeth, with almost straight cuspidate apex; several setules also present. Palp (Fig. 1H, H 2) biarticulae, distal article 7 times as long as proximal article, flat and slightly widening, with 4 stout spiniform distal setae, 1 simple setae and setules. Proximal article very short. Maxilla 2 (Fig. 1I) outer plate wider and with more setae than inner, apical setae only. Inner plate also with setae on inner margin. Maxilliped (Fig. 1J) inner plates reaching midlength of palp article 2, rectangular, covered with fine setules, with 4 short spiniform and 2 simple apical setae. Outer plates subovate, reaching distal margin of article 3, with outer setules and denticles along mediodistal margin and with row of subdistal robust setae. Palp articles not elongated and sparsely setose: article 1 as long as article 2, with 1 outer seta, article 2 about 1.33 times as long and twice as wide as article 3, with 1 outer and 5 inner setae, article 3 slightly longer than article 4, with 1 outer and 10 distal setae, article 4 and with scattered setae. Unguis small (less than one third of dactylus)   
 Gnathopod 1 (Figs. 2A, 2A 1, 3A). Chelate. Basis with evenly spaced anterior setae and posterior ventral setae, more than 3 times as long as ischium. Ischium 1.2 times as long as merus, posterior margin with 3 setae. Merus with 1 posterior seta and setules, as long as carpus. Carpus, 0.4 times as long as propodus naked. Propodus rectangular and elongated, not wider than carpus, with sparse setation, posterior margin with 4 setae, palm without crenulations, distally with 1 lateral and 1 medial strong, curved spiniform setae. Dactylus with proximal and subdistal setae, very slightly exceeding palm.   
 Gnathopod 2 (Fig. 2B, 2B 1, 2B2, 3B). Minutely chelate. Basis weakly setose, 1.7 times longer than ischium. Ischium with sparse setation, slightly shorter than carpus. Merus widening distally, more than half as long as carpus, with numerous setules along posterior margin. Carpus longer than ischium, medioventrally lobate, with pineapple cushion setae. Propodus mitten shaped, with pineapple cushion setae, margin densely covered with scale-like setae, with tuft of dorsodistal setae, posteroventral process guarding dactylus, palm extremely obtuse. Dactylus minute with proximal process and 2 subdistal setae.   
 Pereopods (Fig. 2C–G). Pereopod 3 (Figs 2C) and 4 (Fig. 2D) subequal and unremarkable not modified. Basis more or less naked, 4 times as long as ischium. Ischium more than half as long as propodus, posterior margin with setae. Merus 3 times as long as ischium, posterior margin with setae, strongly on pereopod 4. Carpus narrower than merus and ischium, more than half as long as propodus, with ventral setae. Propodus marginally shorter than merus, posterior margin with 2 setae and distal tuft of small setae. Dactylus less than half as long as propodus, with 1 small dorsal seta. Pereopod 5 (Fig. 2E) basis moderately expanded and weakly setulated Ischium-propodus sparsely setulated and almost exclusively on anterior margin. Merus wider than following articles, with posteroventral extension. Carpus length subequal to merus. Propodus rectangular, 2.5 times as long as ischium Dactylus shorter than propodus, unguis not fused. Pereopod 6 (Fig. 2F) basis more elongated than on P5, weakly setulated. Ischium-propodus sparsely setulated mostly on anterior margin. Merus wider than following articles, with posteroventral extension. Carpus, propodus, and dactylus as on P5. Pereopod 7 (Fig. 2G) basis strongly expanded and weakly setulated. Ischium-propodus sparsely setulated mostly on anterior margin. Merus-dactylus as on P5 & 6.   
 Brood plates (Fig. 3E) elongated, with 5-7 large setae and 0-3 small setae.   
 Gills (Fig. 3F) Present on pereopods 2-7, elongated, pleated.   
 Pleopods (Fig 2H). Normal, peduncle with 2 serrated retinaculae, rami with 10–12 articles.   
 Uropods (Fig 2I–K). Uropod 1 (Fig. 2I) peduncle longer than rami, with 10 spiniform setae along medial and dorsolateral margin. Outer ramus marginally longer than inner ramus with few 2 spiniform setae along dorsal margin. Uropod 2 (Fig. 2J) shorter and stouter than uropod 1, peduncle naked, rami with 1 or 2 dorsal spiniform setae. Uropod 3 (Fig. 2K) peduncle shorter than outer ramus, distal margin with 1 spine, inner ramus reduced to a process, with 1 strong distal spiniform seta. Outer ramus biarticulate, first article twice as long as second article with terminal seta. Second article naked.   
 Telson (Fig. 3C). Subrectangular, entire, lateral margins slightly convex distal margin smoothly rounded, lateral margins with 1 distal submarginal setulated seta.   
 Male. Gnathopod 1 (Fig. 3G, 3G 1). Subchelate. Basis naked, more than 3 times as long as ischium. Ischium 1.2 times as long as merus, posterior margin with 2 setae. Merus naked, as long as carpus. Carpus trapezoid, 0.4 times as long as propodus naked. Propodus much longer and wider than in female, with sparse setation, posterior margin with 4 setae, palm nearly transverse, crenulated, with each notch bearing 2 setae, distally with 1 lateral and 1 medial strong, curved spiniform setae. Dactylus with proximal and subdistal setae, very slightly exceeding palm.   
 Remarks. Except for gnathopod 1 the male is essentially as female in body shape and appendages. Paronesimoides voightae differs from the only other species in the genus, P. lignivorus Pirlot, 1933 by having most of the posteroventral margin of coxa 1 covered by coxa 2, the rectangular shape of gnathopod 2 propodus and the rounded telson. The posteroventral process on article 3 of antenna 2 is not present in the Pirlot illustration (Pirlot 1933:28,pl 48C) and provides an easy visible differentiating character.   
 Ecological notes. This is a common species at the Juan de Fuca Ridge and as its sister species P. lignivorus, is only recorded from a wood fall habitat. It is fairly small, with all specimens <5 mm.
description: Published as part of Larsen, Kim, 2007, Amphipoda (Crustacea; Peracarida) from the Hydrothermal vent system of the Juan De Fuca Ridge, Escabana trough and Gorda ridge, Northeast Pacific. Part I. Lysianassidae and Sebidae, pp. 1-26 in Zootaxa 1445 (1) on pages 2-7, DOI: 10.11646/zootaxa.1445.1.1, http://zenodo.org/record/5077229