Parvochelus serricaudis, Golovan, Olga A., 2015

Golovan, Olga A., 2015, Description of two ubiquitous species of Desmosomatidae (Isopoda: Asellota) from the Northwest Pacific Basin east of the Kuril-Kamchatka Trench, Zootaxa 4039 (2), pp. 201-224: 211-220

publication ID

http://dx.doi.org/10.11646/zootaxa.4039.2.1

publication LSID

lsid:zoobank.org:pub:F89C21B7-4057-48F4-AE97-804B78DBB102

DOI

http://doi.org/10.5281/zenodo.5661880

persistent identifier

http://treatment.plazi.org/id/C1403F00-E87E-FFDB-FF45-FBDDB454F8F8

treatment provided by

Plazi

scientific name

Parvochelus serricaudis
status

sp. nov.

Parvochelus serricaudis   sp. nov.

( Figs 5–12 View FIGURE 5 View FIGURE 6 View FIGURE 7 View FIGURE 8 View FIGURE 9 View FIGURE 10 View FIGURE 11 View FIGURE 12 )

Material examined. Holotype: ( MIMB 31912) copulatory male (2.2 mm), KuramBio St. 2-9 -S; designated here.

Paratypes: ( MIMB 31913) female (2.1 mm) and copulatory male (1.7 mm), used for dissection, 1 male, 8 females, St. 2-9 -S; ( ZMH K- 45099) 17 females, 5 males, St. 2-9 -E; ( MIMB 31914) 63 females, 7 males, 2 mancas, St. 02- 10 -S; ( ZMH K- 45100) 33 females, 8 males, St. 02- 10 -S.

Additional material: ( ZMH K- 45101) female, St. 01- 10 -E; ( MIMB 31915) 2 females, St. 01- 11 -S; ( MIMB 31916) 5 females, St. 7-9 -S; ( ZMH K- 45102) 4 females, St. 07- 10 -E; ( MIMB 31917) female, St. 08-09-S; ( ZMH K- 45103) female, St. 08- 12 -E; ( MIMB 31918) 3 females, St. 9 - 9 -S; ( ZMH K- 45104) female, St. 09- 12 -S; ( MIMB 31919) 3 females, 1 manca, St. 10 -09-S; ( ZMH K- 45105) male, St. 10-12 -E; ( MIMB 31920) 2 females, St. 11 -09- S.

Etymology. The name refers to the clearly serrated lateral margins of the pleotelson meaning “serrate tail”.

Diagnosis. Antenna I with 6 articles. Mandibular palp present, incisor process and lacinia mobilis of left mandible with 4 cusps. Maxilliped palp article 3 with distomedial lobe. Pereopod I merus shorter than width, carpus length approx. 2.3 width, slightly produced at basis of claw-seta. Female pleopod II (operculum) length 1.5 width, lateral sides slightly converging toward broadly rounded posterior margin. Pleotelson lateral margins with large serrations, which are visible in dorsal view.

Description. Holotype, male: body ( Fig. 5 View FIGURE 5 A–C) length 3.9 pereonite 2 widths, body height 0.18 body length. Surface of body covered with cuticular folds. Head: length 0.64 width, 0.12 body length. Frons slightly concave in dorsal view, with serrate ridge around antennal sockets, transverse ridge and frons-clypeal furrow present, clypeus horizontal, labrum curved downward, slightly concave.

Pereonite 1 length 0.27 width, 0.06 body length; pereonites 2–7 lengths in relation to pereonite 1 length: 1.2; 1.4; 1.8; 1.9; 1.5; 1.1; length–width ratios: 0.29; 0.38; 0.60; 0.66; 0.51; 0.41. Pereonites 1–3 narrowing posteriorly, anterior margins concave with slightly convex medial parts, posterior margins slightly concave, lateral margins convex. Pereonites 4–5 almost rectangular, with concave lateral margins, posterior margin of pereonite 5 concave.

Pereonites 6–7 trapezoidal, broadening posteriorly. Coxae I–IV bilobed, produced anteriorly, anterior productions acute, culminating in small, spine-like, robust seta, decreasing in size from anterior to posterior pereonites, anterior production of coxa I stout, almost reaching antennal sockets.

Pleotelson oval, length 0.94 width, 0.17 body length, height 0.56 length, lateral margins serrate, posterior margin convex, with few SS, framed by cuticular membrane ( Fig. 9 View FIGURE 9 C). Anus directed ventrally.

Paratype, male: Antenna I ( Fig. 6 View FIGURE 6 A) length about 0.17 body length, with 6 articles. Article 1 length 1.5 width, with 3 small BS distally. Articles 2–6 length–width ratios: 4.8; 2.0; 2.3; 2.5; 1.8; articles 2–6 lengths in relation to article 1 length: 1.7; 0.53; 0.55; 0.37; 0.21. Article 2 with 1 long distal BS reaching 0.9 length of article. Articles 3 and 5 without setae; article 4 with 2 BS; article 6 with 2 SS, 2 BS and 1 aestetasc terminally.

Antenna II ( Fig. 6 View FIGURE 6 B) length about 0.60 body length. Articles 1–6 length–width ratios: 1.0; 0.79; 0.95; 1.0; 2.7; 4.6; articles 2–6 lengths in reation to article 1 length: 0.91; 1.3; 1.0; 4.2; 5.6. Article 3 with robust distolateral UBS; article 5 with 1 small distolateral UBS; article 6 distally with 1 small UBS, 3 BS and 3 SS. Flagellum length 0.39 antenna II length, with 12 articles, article 1 length 0.31 flagellum length; articles bearing numerous fine SS distally.

Mandible ( Fig. 7 View FIGURE 7 A, B) incisor process with 4 cusps. Lacinia mobilis of left mandible with 4 cusps; lacinia mobilis of right mandible serrated; spine row with 3 spines. Molar process triangular, distally with about 7 setae. Palp articles with numerous fine SS, article 1 with 1 distal SS; article 2 length 1.9 article 1 length, article 3 length 1.1 article 1 length, almost straight.

Maxilla I ( Fig. 7 View FIGURE 7 C) lateral endite distally with 10 robust serrate setae; mesial endite width 0.63 lateral endite width, with 1 long and 1 shorter setae distally.

Maxilla II ( Fig. 7 View FIGURE 7 D) lateral endite longest, middle endite shortest, width 0.68 lateral endite width, mesial endite width 1.1 of lateral endite width; endites distally bearing 3 (lateral), 2 (middle) and 5 (mesial) serrate setae respectively and numerous long fine SS.

Maxilliped ( Fig. 7 View FIGURE 7 E) basis length 2.5 width; endite length 2.7 width, 0.53 basis length, with 2 retinaculae, distal margin with 3 fan setae and 1 stout and 2 slender setulate setae. Palp length approximately 0.9 basis length, 1.1 width; articles 3–4 with rounded distomedial lobes, lobe of article 3 length 0.47 article 3 lateral length; article 1 width 0.76 basis width, lateral length 0.17 basis length; articles 2–5 lengths in relation to article 1 lateral length: 2.5; 1.5; 1.1; 0.97; articles 1–3 lateral length to medial length ratios: 1.4; 1.5; 0.56; articles 1–5 lateral length to width ratios: 0.54; 0.98; 0.57; 1.1; 2.7; articles 1, 2, 4 with 1, 2, 2 distomedial SS, respectively, article 3 with 3 medial SS, article 5 with 4 distal SS. Epipod length 2.7 width, 1.2 basis length, distal half narrowing, bent medially; lateral margin with hyaline membrane supported by fine setae; surface covered with cuticular folds.

Pereopod I ( Fig. 6 View FIGURE 6 C) basis to dactylus length-width ratios: 6.4; 1.5; 0.95; 2.3; 3.9; 3.8; length ratios of ischiumdactylus compared to basis length: 0.26; 0.16; 0.52; 0.46; 0.11. Basis with 1 dorsal and 1 distoventral SS; ischium with 1 distoventral SS; merus with 1 distoventral and 1 distodorsal SS. Carpus dorsal and ventral margins parallel, almost straight, distoventral corner slightly produced; ventrally 1 small SS at mid-length and 1 twice longer SS proximally to base of claw-seta; claw-seta length 0.69 propodus length, slender seta between claw-seta and propodus, seta length about 0.85 claw-seta length. Propodus widest proximally, with 2 dorsal and 1 distoventral fine SS, ventral margin with hyaline membrane supported by 3 fine setae. Surface of carpus and propodus covered with cuticular folds. Dactylus dorsal claw 0.22 dactylus length, ventral claw extends beyond dorsal claw.

Pereopod II ( Fig. 8 View FIGURE 8 A) basis to dactylus length-width ratios: 6.8; 2.6; 1.6; 6.8; 5.3; 6.6; length ratios of ischiumdactylus compared to basis length: 0.32; 0.20; 0.76; 0.44; 0.27. Basis with 1 distoventral DSS; ischium with 1 ventral DSS; merus with 1 DSS distoventrally, 1 DSS and 1 SS distodorsally. Carpus dorsal margin with 3 DSS, ventral margin with 4 DSS increasing in size towards propodus. Propodus dorsal margin with 2 long robust DSS, ventral margin with 4 short DSS and 1 distal SS. Ventral margins of carpus and propodus with hyaline membranes. Dactylus with 3 fine distolateral setae, dorsal claw length 0.32 dactylus length, ventral claw length about 0.30 dorsal claw length, 2 setae inserted between claws.

Pereopod III ( Fig. 8 View FIGURE 8 B) basis length 7.0 width, with 3 ventral SS; ischium-dactylus broken, missing.

Pereopod IV ( Fig. 8 View FIGURE 8 C) basis to dactylus length-width ratios: 5.3; 2.4; 1.7; 6.8; 6.5; 9.6; length ratios of ischium-dactylus compared to basis length: 0.42; 0.28; 0.89; 0.59; 0.37. Basis with 1 SS and 1 DSS dorsally, 2 SS and 1 DSS ventrally; ischium with 1 ventral DSS; merus with 1 distoventral and 1 distodorsal DSS; carpus with 4 ventral and 3 dorsal DSS increasing in size towards propodus; propodus with 2 large dorsal DSS; dactylus dorsal claw 0.45 dactylus length, ventral claw length about 0.25 dorsal claw length.

Pereopod V ( Fig. 8 View FIGURE 8 D) basis length 6.7 width, with 1 dorsal SS; ischium length 3.1 width, 0.54 basis length, with 2 dorsal DSS; merus-dactylus broken, missing.

Pereopod VI ( Fig. 8 View FIGURE 8 E) basis to dactylus length-width ratios: 5.7; 2.8; 2.1; 5.7; 7.1; 19.8; length ratios of ischium-dactylus compared to basis length: 0.54; 0.27; 0.86; 0.76; 0.55. Basis with 1 dorsal and 3 ventral fine DSS; ischium with 1 dorsal DSS; merus with 2 SS distoventrally, 1 SS and 1 DSS distodorsally; carpus with 5 ventral and 4 dorsal long DSS, ventral margin with hyaline membranes; propodus dorsal margin with row of 4 long DSS, 1 UBS, 5 long DSS, 1 UBS, ventral margin with 4 long DSS increasing in size towards dactylus; dactylus dorsal claw length 0.30 dactylus length, ventral claw length about half dorsal claw length.

Pereopod VII ( Fig. 8 View FIGURE 8 F) basis to dactylus length-width ratios: 6.7; 3.7; 2.0; 6.7; 7.3; 8.9; length ratios of ischium-dactylus to basis: 0.53; 0.25; 0.86; 0.72; 0.53. Basis with 1 dorsal BS and 2 ventral fine DSS; merus with 1 distodorstal and 2 distoventral fine DSS; carpus with 4 ventral and 3 dorsal long DSS; propodus dorsal margin with row of 2 long DSS, 1 UBS, 4 long DSS, 1 UBS, ventral margin with 1 long DSS; dactylus with 2 SS dorsally, dactylus dorsal claw 0.34 dactylus length, ventral claw about half dorsal claw length, 1 seta inserted between claws.

Pleopod I ( Fig. 9 View FIGURE 9 A) oval, length 1.6 widths, medially with few SS; distolateral lobes not developed, distomedial lobes 0.24 pleopod 1 length, rounded, bearing 8–9 marginal SS.

Pleopod II ( Fig. 9 View FIGURE 9 B) protopod length 3.0 width, with 2 distolateral SS. Endopod basal article length 1.7 width, 0.30 protopod length; stylet length 11.9 width, 1.4 protopod length, sperm duct opening at about 0.16 length of stylet, distal part of stylet narrowing, acute. Exopod length 1.8 width, 0.35 protopod length.

Pleopods III–V similar to those of female (see below).

Uropod ( Fig. 9 View FIGURE 9 C) length 0.43 pleotelson length. Protopod length 1.3 width, with 4 lateral and 1 distomedial UBS. Endopod length 5.4 width, 1.8 protopod length, lateral and distal margins with about 5 BS and 2 SS.

Paratype, female: body ( Fig. 5 View FIGURE 5 D–H) wider, than that of male (length 3.3 width), with larger pereonites 2–4. Pereonites 2–7 length in relation to pereonite 1 length: 1.4; 1.8; 2.2; 1.8; 1.2; 1.3. Coxae with less pronounced anterolateral projections than male. Pleotelson length 1.2 width.

Antenna I ( Fig. 10 View FIGURE 10 A) with 6 articles. Articles 1–6 length–width ratios: 1.4; 4.4; 1.7; 2.0; 3.4; 2.7; articles 2–6 lengths to article 1 length ratios: 2.1; 0.60; 0.67; 0.44; 0.25; article 1 without setae, article 2 with 3 long BS.

Antenna II ( Fig. 10 View FIGURE 10 B) about half body length. Articles 1–6 length–width ratios: 1.2; 0.82; 0.96; 1.2; 6.9; 8.9; articles 2–6 lengths to article 1 length ratios: 0.87; 0.99; 0.99; 4.7; 5.9; article 3 with 1 short robust UBS laterally. Flagellum length 0.39 antenna II length, with 7 articles, flagellar articles 2–6 with 1–2 distal fine SS, article 7 with 6 terminal fine SS.

Mouthparts ( Fig. 10 View FIGURE 10 C–G) and pereopods ( Figs 5 View FIGURE 5 I, 11) similar to those of male, except for minor differences in proportion and setation.

Operculum ( Fig. 12 View FIGURE 12 A) length 1.5 width, lateral sides slightly converging toward posterior margin; posterior margin broadly rounded, with inconspicuous angle medially, framed by hyaline membrane, with 1 SS.

Pleopod III ( Fig. 12 View FIGURE 12 B) protopod length 1.1 width. Endopod length 1.5 width, distal margin broadly rounded, with 3 pappose setae, setae lengths about as long as endopod. Exopod length 0.77 endopod length, narrowing distally, with 1 terminal SS.

Pleopod IV ( Fig. 12 View FIGURE 12 C) protopod length 0.85 width. Endopod length 1.5 width. Exopod length 4.5 width and about 1.1 endopod length, with terminal pappose seta, which about 1.5 times longer than exopod, lateral margin with fine SS.

Pleopod V ( Fig. 12 View FIGURE 12 D) endopod length 2.8 width, with 1 distal SS, lateral margin with fine SS.

Uropod ( Fig. 12 View FIGURE 12 E) protopod length 1.8 width.

Remarks. The habitus of P. serricaudis   sp. nov. and the type species P. russus   are similar, however, the new species has more pronounced serrations on the pleotelson lateral sides, which are clearly visible on a total view. P. serricaudis   sp. nov. can easily be distinguished from P. russus   by the shape of pereopod I, which in the new species is much stouter and enlarged when compared to pereopod II, its carpus length 2.3 times longer than wide, slightly produced at the base of the claw-seta. In contrast, the pereopod I of P. russus   is slender, not enlarged, possessing a weak chela with a long slender carpus (3.7 times longer than wide), which is not produced at the base of the clawseta. The mandibles of P. russus   lack palps. In P. serricaudis   sp. nov. the mandibular palps are present but fragile and easily break when specimens are handled. The female operculum in P. serricaudis   has almost parallel lateral sides, slightly converging toward the posterior margin; the latter is broadly rounded, with the inconspicuous indentation medially. In P. russus   the female operculum is tapering toward the distal end. Furthermore, the two species differ in the number of antennal articles and the mouthparts morphology.

Distribution. Northwest Pacific to the east of the Kuril-Kamchatka Trench, from 40.2210 °N, 148.1038 °E – 40.2062 °N, 148.0905 °E to 46.2268 °N, 155.5567 °E – 46.2487 °N, 155.5428 °E, at depth ranges from 4830–4863 to 5423–5429 m.

MIMB

Museum of the Institute of Marine Biology

ZMH

Zoologisches Museum Hamburg