Sinelobus kisui, Hirano & Kakui, 2022

Hirano, Kyoko & Kakui, Keiichi, 2022, A new brackish tanaidacean, Sinelobus kisui sp. nov. (Crustacea, Peracarida, Tanaidacea), from Japan, with a key to Sinelobus species and barcode information from two loci, Zoosystematics and Evolution 98 (2), pp. 245-256 : 245

publication ID

https://dx.doi.org/10.3897/zse.98.84818

publication LSID

lsid:zoobank.org:pub:506932DF-85C7-491E-AA6E-C832996FC66D

persistent identifier

https://treatment.plazi.org/id/FA0362B0-1A05-41B3-AC84-DA36C622D3BA

taxon LSID

lsid:zoobank.org:act:FA0362B0-1A05-41B3-AC84-DA36C622D3BA

treatment provided by

Zoosystematics and Evolution by Pensoft

scientific name

Sinelobus kisui
status

sp. nov.

Sinelobus kisui sp. nov.

[Japanese name: Kisui-tanaisu] Figs 2 View Figure 2 , 3 View Figure 3 , 4 View Figure 4 , 5 View Figure 5 , 6 View Figure 6

Sinelobus stanfordi : Ariyama and Ohtani 1990, 25-26, figs 2-5; Kakui 2016, 610 (not Sinelobus stanfordi Richardson, 1901).

Sinelobus sp. 1: Kakui et al. 2011, 751; Kakui et al. 2012, 128-129, fig. 1D.

Sinelobus sp.: Kaji et al. 2016, 3-8, figs 1-5; Kakui et al. 2021, 3.

Diagnosis.

Antennal article 2 with outer distal simple seta. Maxillipedal endite with one mid-inner and two dorsodistal spiniform setae; and two ventro-subdistal circumplumose setae, inner one longer than outer. Pereopod 1 with carpus bearing two dorsal and two ventral simple setae; propodus with middle setulate seta. Dorsodistal crotchet on carpi of pereopods 2 and 3 shorter than half propodus length. Pereopod 3 basis with ventral PSS. Pereopods 2-6 with carpus bearing five distal crotchets. Pleopod 1 protopod without inner plumose setae. In strongly sexually dimorphic males, chelipedal merus with three ventral processes; angle of dorsal margin of fixed finger to distal margin of palm about 90°.

Etymology.

The specific name is derived from the Japanese noun Sinelobus kisui (brackish water), referring to the habitat of this species, and also referable to the Japanese name Kisui-tanaisu, proposed by Ariyama and Ohtani (1990) for this species in the Shin Yodo River, Osaka.

Material examined.

Holotype: Female , ICHUM8301 (BL 4.00, CW 0.67), Hagi, Yamaguchi, Japan (34°26.168'N, 131°25.140'E) (type locality), among tubular Ulva algae, brackish stream, 22 May 2014, coll. by Keiichi Kakui GoogleMaps . Allotype: Male, ICHUM8302 (BL 3.17, CW 0.62), same collection data as for holotype. Paratypes: Five females (ICHUM8303, BL 3.06, CW 0.56; ICHUM8304, BL 2.91, CW 0.52; ICHUM8305, CW0.51, INSD accession number LC705431 View Materials [COI]; ICHUM8306, BL 3.18, CW 0.52; ICHUM8312, BL 2.10, CW0.42, INSD accession numbers LC705430 View Materials [18S], LC705432 View Materials [COI]). Six males (ICHUM8307, BL 3.04, CW0.56; ICHUM8308, BL 2.85, CW0.56, INSD accession number LC705433 View Materials [COI]; ICHUM8309, BL 2.89, CW 0.52; ICHUM8310, BL 3.36, CW 0.61; ICHUM8311, BL 2.42, CW 0.46; ICHUM8313, BL 2.46, CW 0.53). Collection data for ICHUM8303-8311 same as for holotype. ICHUM8312 and 8313 hatched in an aquarium in Kakui laboratory, Sapporo, descendants of individuals collected from type locality on 22 May 2014 .

Other material: One female, ICHUM8314 (BL 2.79, CW 0.51; INSD accession number LC664100 View Materials [COI]), Aya River, Sakaide, Kagawa, Japan (approximate coordinates 34°19.693'N, 133°52.499'E), 2 June 2008, coll. by Yoshihiro Hayashi; one male, ICHUM4031 (INSD accession numbers AB618192 View Materials [18S], LC664101 View Materials [COI]), same collection data as for ICHUM8314 ; one male, OMNH-Ar12459 (BL 2.97, CW 0.67), Station 4, Shin Yodo River, Osaka, Osaka, Japan (approximate coordinates: 34°41.447'N, 135°26.613'E), under rocks, 19 February 1989, coll. by Michio Ohtani GoogleMaps .

Description of females (based on holotype unless noted otherwise).

Body (Figs 2a View Figure 2 , 3a, b View Figure 3 ) 5.96 times as long as wide, with brown pigmentation (retained in ethanol). Cephalothorax 0.19 times BL, tapering anteriorly, with mid-lateral pair of simple setae and pair of simple setae posterior to eyes. Dorsal pigmentation pattern on carapace: anterior region dark; subanterior region without dark pigmentation; posterolateral region with two dark diagonal bands; reticulate pattern of pigmentation elsewhere (often faint). Pereonites 1-6 with length ratio 1.00:1.71:2.07:2.50:2.58:2.20; all with one or two pairs of simple setae. Pereonites 1-6 width-to-length ratio 0.30, 0.51, 0.63, 0.82, 0.86, and 0.80, respectively. Pleonites 1-3 with pair of dorsal simple seta; pleonites 1 and 2 with dorso-transverse plumose setal row (but incomplete, absent in dorsal region); pleonites 2 and 3 with lateral plumose setal row. Pleonite 4 with several pairs of simple setae. Pleotelson with seven pairs of simple setae.

Antennule (Fig. 4a View Figure 4 ) 0.65 times as long as cephalothorax; articles 1-4 with length ratio 1.00:0.37:0.33:0.03. Article 1 with two outer distal and one inner distal simple setae, and several proximal and distal PSS. Article 2 with three outer distal and two inner distal simple setae, and several distal PSS. Article 3 with two distal simple setae and several distal PSS. Article 4 with tuft of distal simple setae, distal PSS, and two aesthetascs.

Antenna (Fig. 4c View Figure 4 ) 0.84 times as long as antennule; articles 1-6 with length ratio 1.00:3.00:1.08:3.29:2.37:0.34. Articles 1 and 3 naked. Article 2 with one outer distal, one ventrodistal, and one inner distal simple setae. Article 4 with distal simple seta and distal PSS. Article 5 with three distal simple setae and three distal PSS. Article 6 with tuft of distal simple setae.

Labrum (Fig. 4e View Figure 4 ) setulate distally. Mandibles (Fig. 4f-i View Figure 4 ) with well-developed molar process bearing many small teeth on masticatory surface; left mandible (Fig. 4f, g View Figure 4 ) with weakly denticulate incisor, wide denticulate lacinia mobilis, and bifurcate serrate accessory seta; right mandible (Fig. 4h, i View Figure 4 ) with seven-toothed incisor, peg-like lacinia mobilis, and bifurcate serrate accessory seta. Labium (Fig. 4j View Figure 4 ) with distally setulate inner lobe; outer lobes smaller. Maxillule (Fig. 4k View Figure 4 ) endite bearing eight distal spiniform setae and outer subdistal setation; palp broken. Maxilla (ICHUM8304; Fig. 4l View Figure 4 ) with small serrations on outer distal margins.

Maxilliped (Fig. 4m View Figure 4 ) with coxa bearing simple seta (not illustrated). Basis with ventrodistal simple seta. Endite with outer distal tufts of fine setae, one mid-inner and two dorsodistal spiniform setae; and two ventro-subdistal circumplumose setae, inner one longer than outer; distal region setulate. Palp article 1 with outer distal serrations; article 2 with one outer distal and four inner simple setae, and inner distal serrate spiniform seta; article 3 with four inner distal simple setae and six inner plumose setae; article 4 with one mid-outer and two outer-subdistal simple setae, two inner plumose setae, and five distal serrate setae. Epignath (Fig. 4n View Figure 4 ) with kidney-shaped lobe, margins finely setulate; terminal seta setulate.

Cheliped (Fig. 5a, b View Figure 5 ) with triangular articulation to cephalothorax via sclerite (Fig. 3b View Figure 3 ). Basis slightly longer than wide, with one outer dorsal and one ventrodistal simple setae. Merus with one outer dorsal and one ventral simple setae. Carpus 1.46 times as long as wide, with one dorsal, two dorsodistal and two ventral simple setae. Propodus 0.77 times as long as carpus; palm with two outer and one inner simple setae at insertion of dactylus; fixed finger with one ventral, four outer subdistal, and two inner subdistal simple setae, and dorso-subdistal broad lamellar expansion and triangular claw. Dactylus as long as fixed finger, with inner simple seta, row of ventral spiniform setae, and bifurcate serrate seta; unguis triangular, curved ventrally.

Pereopod 1 (Fig. 5e, f View Figure 5 ) length 0.25 times BL, with length ratio of basis, merus, carpus, propodus, and dactylus-unguis 1.00:0.28:0.36:0.51:0.40. Coxa with dorsal simple seta. Basis cylindrical, narrow, 4.61 times as long as wide, with dorso-subproximal simple seta and dorso-subproximal PSS. Merus with one ventrodistal simple seta. Carpus with two dorsal and two ventrodistal simple setae. Propodus with one dorsodistal and two ventrodistal simple setae, middle PSS, and middle setulate seta. Dactylus naked; unguis shorter than dactylus, naked.

Pereopod 2 (Fig. 5g-i View Figure 5 ) with length ratio of articles from basis to propodus 1.00:0.53:0.34:0.46. Coxa with dorsal simple seta (not illustrated). Basis cylindrical, narrow, 3.17 times as long as wide, with ventrodistal simple seta and dorso-subproximal PSS. Merus with ventrodistal simple seta and ventrodistal crotchet (Fig. 5h View Figure 5 ). Carpus with dorsodistal simple seta and six distal crotchets (dorsodistal one shorter than half propodus length). Propodus with two dorsodistal and one ventrodistal simple setae and mid-dorsal PSS. Dactylus (ICHUM8303; Fig. 5i View Figure 5 ) naked; unguis shorter than dactylus, naked.

Pereopod 3 (ICHUM8303; Fig. 5j View Figure 5 ) with length ratio of articles from basis to dactylus-unguis 1.00:0.39:0.34:0.36:0.37; similar to pereopod 2, except basis with ventral PSS, carpus with five distal crotchets, and propodus with dorsodistal simple seta.

Pereopod 4 (ICHUM8303; Fig. 5k View Figure 5 ) with length ratio of articles from basis to dactylus-unguis 1.00:0.29:0.32:0.43:0.32. Coxa with simple seta. Basis 3.21 times as long as wide, with ventrodistal simple seta, and two dorso-subproximal and two ventro-subdistal PSS. Merus with outer distal simple seta and two ventrodistal crotchets. Carpus with inner dorsodistal simple seta and five distal crotchets. Propodus with outer distal simple seta, dorso-subdistal PSS, and one outer dorsodistal and one inner dorsodistal setulate setae. Dactylus-unguis fused to form claw, strongly arcuate, with inner and outer rows of ventral spines.

Pereopod 5 (Fig. 5l View Figure 5 ) with length ratio of articles from basis to dactylus-unguis 1.00:0.43:0.30:0.51:0.35; similar to pereopod 4.

Pereopod 6 (Fig. 5m, n View Figure 5 ) with length ratio of articles from basis to dactylus-unguis 1.00:0.40:0.33:0.58:0.39; similar to pereopod 4 except basis without ventro-subdistal PSS and propodus with five inner distal flattened denticulate setae and inner distal biserrate seta.

Pleopod 1 (Fig. 6a View Figure 6 ) with protopod bearing six outer plumose setae; endopod with one inner and 14 outer plumose setae, and outer distal step-tipped plumose seta; exopod 1.42 times as long as endopod, with 29 outer plumose setae. Pleopod 2 (Fig. 6b View Figure 6 ) with protopod bearing six outer plumose setae; one inner plumose seta present on right protopod but absent on left; endopod with one inner and 13 outer plumose setae, and outer distal step-tipped plumose seta; exopod 1.37 times as long as endopod, with 30 outer plumose setae. Pleopod 3 (Fig. 6c View Figure 6 ) smaller than pleopods 1 and 2, with protopod bearing three outer plumose setae; endopod with one inner and 11 outer plumose setae, and outer distal step-tipped plumose seta; exopod 1.36 times as long as endopod, with 22 outer plumose setae.

Uropod (ICHUM8303; Fig. 6g View Figure 6 ) with four articles (protopod and triarticulate ramus). Protopod with four distal simple setae. Ramus article 1 naked; article 2 longest, with one middle and two distal simple setae and two distal PSS; article 3 with one middle and four distal simple setae.

Description of males (based on allotype).

Body (Figs 2b View Figure 2 , 3c, d View Figure 3 ) similar to female except for cephalothorax shape: cephalothorax strongly narrowed anteriorly.

Antennule (Fig. 4b View Figure 4 ) 0.93 times as long as cephalothorax; articles 1-4 with length ratio of 1.00:0.33:0.27:0.02. Article 1 with two outer distal and two inner distal simple setae, and several proximal and distal PSS. Article 2 with three outer distal and two inner distal simple setae, and several distal PSS. Article 3 with two distal simple setae and several distal PSS. Article 4 with tuft of distal simple setae, distal PSS, and three aesthetascs.

Antenna (Fig. 4d View Figure 4 ) 0.84 times as long as antennule; articles 1-6 with length ratio 1.00:2.47:1.59:3.43:1.93:0.19. Articles 1 and 3 naked. Article 2 with one outer distal, one ventrodistal, and one inner distal simple setae. Article 4 with distal simple seta and distal PSS. Article 5 with three distal simple setae and three distal PSS. Article 6 with tuft of distal simple setae and several distal PSS.

Labrum, mandibles, labium, maxillule, maxilla, maxilliped, and epignath similar to those of female.

Cheliped (Fig. 5c, d View Figure 5 ) with triangular articulation to cephalothorax via sclerite (Fig. 3d View Figure 3 ). Basis as long as wide, with one outer dorsal and one ventrodistal simple setae. Merus with one outer dorsal and one ventral simple setae, inner broad thickening (Fig. 5d View Figure 5 , gray arrowhead), and three ventral processes (Fig. 5c, d View Figure 5 , white arrowheads). Carpus 1.22 times as long as wide, with one dorsal, two dorsodistal, and two ventral simple setae, and three ventral processes (Fig. 5c, d View Figure 5 , black arrowheads). Chela 1.15 times as long and 1.24 times as wide as carpus; ventral margin with middle simple seta and one proximal and one middle projection (Fig. 5c View Figure 5 , gray and black arrows, respectively). Palm with two outer and one inner simple setae at insertion of dactylus. Fixed finger with four outer subdistal and two inner subdistal simple setae, dorso-subdistal triangular lamellar expansion, and triangular claw; base of fixed finger distant (greater than dactylus width) from base of dactylus; angle of dorsal margin of fixed finger to distal margin of palm about 90°. Dactylus strongly curved ventrally, with inner simple seta, row of ventral spiniform setae, and bifurcate serrate seta; unguis triangular.

Pereopods 1-6 more slender than but similar to those of females, with differences in setal number (see Suppl. material 1: Table S1 for details).

Pleopods (Fig. 6d-f View Figure 6 ) similar to those of female, with differences in setal number (see Suppl. material 1: Table S1 for details).

Uropod similar to that of female.

Variation.

In addition to the holotype and allotype, two female (ICHUM8303, ICHUM8304) and one male (ICHUM8307) paratypes of Sinelobus kisui sp. nov. were dissected, and selected characters were observed for the antennule, antenna, maxilliped, cheliped, pereopods 1-6, and pleopods 1-3. The raw morphological data we obtained are in Suppl. material 1: Table S1. All specimens shared the same state for the following selected characters: (1) antennule with two (females) or three (males) aesthetascs; (2) antennal article 2 with one outer distal, one ventrodistal, and one inner distal simple setae; (3) maxillipedal endite with one mid-inner and two distal spiniform setae, and two ventro-subdistal circumplumose setae, inner one longer than outer; (4) pereopod 1 with carpus bearing two dorsal and two ventral simple setae and propodus bearing one middle setulate seta; (5) dorsodistal crotchet on carpi of pereopods 2 and 3 shorter than half propodus length; (6) pereopod 3 basis with one ventral PSS; (7) pleopod 1 protopod lacking inner plumose setae. Two strongly sexually dimorphic males (allotype and paratype ICHUM8307) shared all states observed in the chelipeds.

The following setae varied in number among specimens (selected characters only are presented; ranges are in parentheses): ventrodistal simple setae on basis of pereopods 4-6 (1-2); inner distal flattened denticulate setae on pereopod 6 propodus (4-5); outer plumose setae on protopods of pleopods 1 and 2 (4-6) and on protopod of pleopod 3 (3-4); outer plumose setae on endopods of pleopods 1 and 2 (8-14) and on endopod of pleopod 3 (8-11); outer plumose setae on exopods of pleopods 1 and 2 (21-30) and on exopod of pleopod 3 (20-22). In the holotype individual, the right pleopod-2 protopod bears one inner plumose seta (Fig. 6b View Figure 6 ) but the left one lacks it. This seta was not found on the corresponding article in the other four individuals, suggesting that its presence in the one case observed may be abnormal. We observed six distal crotchets on carpi of left pereopods 2 and 3 in the holotype individual, but all other pereopods we observed bore five, indicating the former state may be abnormal.

Morphology of individuals from Kagawa and Osaka.

One female from Kagawa (ICHUM8314) and one strongly sexually dimorphic male from Osaka (OMNH-Ar12459) were dissected and observed. In the former individual, all diagnostic character states were observed, except for those found only in strongly sexually dimorphic males. The latter individual was whitish, having lost its pigmentation (but see Ariyama and Ohtani 1990), and showed all diagnostic character states.

Genetic information.

One partial 18S (INSD accession number LC705430; 1920 bp long) and three COI (LC705431-LC705433; 815 bp long, encoding 271 amino acids) sequences were determined from Yamaguchi individuals. The 18S sequence was identical to that from a Sinelobus sp. 1 sensu Kakui et al. (2011) individual from Kagawa (AB618192, Kakui et al. 2011) but was 4.6% divergent in K2P distance from an 18S sequence from Sinelobus sp. 2 sensu Kakui et al. (2011) (AB618193, Kakui et al. 2011). For COI, K2P distances among three individuals from Yamaguchi were 0.0-0.4%; those between three Yamaguchi individuals and two Kagawa individuals (LC664100, LC664101; 658 bp long, encoding 219 amino acids) were 0.3-1.5%; and that between two Kagawa sequences was 1.5%.

Kingdom

Animalia

Phylum

Arthropoda

Class

Malacostraca

Order

Tanaidacea

Family

Tanaididae

Genus

Sinelobus

Loc

Sinelobus kisui

Hirano, Kyoko & Kakui, Keiichi 2022
2022
Loc

Sinelobus stanfordi

Hirano & Kakui 2022
2022
Loc

Sinelobus stanfordi

Hirano & Kakui 2022
2022
Loc

Sinelobus

Hirano & Kakui 2022
2022
Loc

Sinelobus

Hirano & Kakui 2022
2022