Paronesimoides voightae, Larsen, 2007

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, Zootaxa 1445 (1), pp. 1-26 : 2-7

publication ID

https://doi.org/ 10.11646/zootaxa.1445.1.1

publication LSID

lsid:zoobank.org:pub:7F76D8A3-51D1-4C24-B044-A8723CBBF05E

DOI

https://doi.org/10.5281/zenodo.5077406

persistent identifier

https://treatment.plazi.org/id/935CDD7C-075A-FFBC-749F-A9BAFACCFB9D

treatment provided by

Felipe

scientific name

Paronesimoides voightae
status

sp. nov.

Paronesimoides voightae n. sp.

( Figs. 1–3 View FIGURE 1 View FIGURE 2 View FIGURE 3 ).

Material examined. Holotype, ovigerous female, 5.2 mm. ( FMNH # 13756 View Materials ), Station code VOIJALV4046F, Dive 4046, near Wuzza Bare Mount, 3 September, 2004; 47°47.09’ N 127°41.443’ E. Depth 2656 m GoogleMaps . Paratypes: 1 male, 4.1 mm. (KMNH IvR 700248), 1 male (dissected). 3 sex? 1.3 -2 mm, ( FMNH # 12848 View Materials ) . 1 ovigerous female, 1 male, 7 sex? 1.8–4.5 mm, ( FMNH # 12895 View Materials ) . 1 male 2.8 mm, 3 sex? 1.8–2.2 mm, ( FMNH # 12899 View Materials ) . 1 ovigerous female 4.9 mm, (dissected), 1 sex? 2.2 mm, ( FMNH # 12906 View Materials ) . 2 specimens, ( FMNH # 12932 View Materials ) . 2 males, 1 ovigerous female, 3 sex? 2.4–4.7 mm. 1 ovigerous female, ( FMNH # 12987 View Materials ) . 1 ovigerous female, 5.3 mm, ( FMNH # 13022 View Materials ) . 1 ovigerous female, 4.7 mm (dissected), 2 males 4.4–4.7 mm, ( FMNH # 13027 View Materials ) .

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 View FIGURE 1 ). 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 View FIGURE 1 , 3 View FIGURE 3 AB, 2C–G). Coxa 1 ( Fig. 3A View FIGURE 3 ) 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 View FIGURE 3 ) rectangular with small indentation at posteroventral corner, w/d ratio 0.5. Coxa 3 ( Fig. 2C View FIGURE 2 ) of similar shape and size but without indentation, w/d ratio 0.6. Coxa 4 ( Fig. 2D View FIGURE 2 ) only marginally larger than coxae 2–3, with posterior margin strongly excavated, w/d ratio 0.8. Coxa 5 ( Fig. 2E View FIGURE 2 ) larger than coxa 6–7, equilobate, w/d ratio 1.3.Coxa 6 ( Fig. 2F View FIGURE 2 ) 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 View FIGURE 1 ). 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 View FIGURE 1 ). 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 View FIGURE 1 ): upper lip almost completely fused with epistome, with setose slightly lobed apex. Mandibles ( Fig. 1E, 1F View FIGURE 1 ) incisor ( Fig. 1E1 View FIGURE 1 ) well developed, with one denticle; spine row ( Fig. 1E 1, 1E View FIGURE 1 2 View FIGURE 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 View FIGURE 1 ) outer lobes with distal curved process heavily setose along apical margin. Mandibular processes rather weak and tapering. Maxilla 1 ( Fig 1H View FIGURE 1 ): inner plate slender, with 1 setulose and 1 or 2 small simple apical setae. Outer plate ( Fig. 1H, 1H1 View FIGURE 1 ) 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 View FIGURE 1 2 View FIGURE 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 View FIGURE 1 ) outer plate wider and with more setae than inner, apical setae only. Inner plate also with setae on inner margin. Maxilliped ( Fig. 1J View FIGURE 1 ) 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 View FIGURE 2 1 View FIGURE 1 , 3A View FIGURE 3 ). 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 View FIGURE 2 1 View FIGURE 1 , 2B2 View FIGURE 2 , 3B View FIGURE 3 ). 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 View FIGURE 2 ). Pereopod 3 ( Figs 2C View FIGURE 2 ) and 4 ( Fig. 2D View FIGURE 2 ) 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 View FIGURE 2 ) 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 View FIGURE 2 ) 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 View FIGURE 2 ) basis strongly expanded and weakly setulated. Ischium-propodus sparsely setulated mostly on anterior margin. Merus-dactylus as on P5 & 6.

Brood plates ( Fig. 3E View FIGURE 3 ) elongated, with 5-7 large setae and 0-3 small setae.

Gills ( Fig. 3F View FIGURE 3 ) Present on pereopods 2-7, elongated, pleated.

Pleopods ( Fig 2H View FIGURE 2 ). Normal, peduncle with 2 serrated retinaculae, rami with 10–12 articles.

Uropods ( Fig 2I–K View FIGURE 2 ). Uropod 1 ( Fig. 2I View FIGURE 2 ) 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 View FIGURE 2 ) shorter and stouter than uropod 1, peduncle naked, rami with 1 or 2 dorsal spiniform setae. Uropod 3 ( Fig. 2K View FIGURE 2 ) 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 View FIGURE 3 ). Subrectangular, entire, lateral margins slightly convex distal margin smoothly rounded, lateral margins with 1 distal submarginal setulated seta.

Male. Gnathopod 1 ( Fig. 3G, 3G View FIGURE 3 1 View FIGURE 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.

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