Sinelobus vanhaareni, Bamber, 2014

Bamber, Roger N, 2014, Two new species of Sinelobus Sieg, 1980 (Crustacea: Tanaidacea: Tanaididae), and a correction to the higher taxonomic nomenclature, Journal of Natural History 48 (33 - 34), pp. 2049-2068 : 2052-2059

Sinelobus vanhaareni sp. nov.

( Figures 1–4 )

Sinelobus stanfordi van Haaren & Soors 2009 , 1–9, figs 1–5, non- Tanais stanfordi Richardson, 1901 .

Tanais dulongii Rander et al. 2009 , 47–51, fig. 1, non- Gammarus dulongii Audouin, 1826 .

Type material

Holotype. 1 brooding ♀, ( BMNH xxxx), Hoek van Holland, Netherlands, 51° 57’45.1”N 04°08’30.1”E, 29 September 2011 (leg. Mirjam Kuitert).

Allotype. 1 ♂, ( BMNH xxxx), same data as holotype.

Paratypes. 15♀♀ (2 with oostegites, 3 brooding), 2♂♂, 2 subadult ♂♂, 2 juveniles, 1 manca, ( BMNH xxxx), same data as holotype . 28♀♀ (5 brooding), 3♂♂, 2 subadult ♂♂, 6 juveniles ( BMNH xxxx), Oeverbos West , Netherlands, 51°54’29”N 04°16’05.5”E, 29 September 2011 (leg. Mirjam Kuitert) . 1♀, 1♂ ( BMNH xxxx), Hoek van Holland, Netherlands, 51°57’45”N 04°08’30”E, 4 October 2012 (leg. Ton van Haaren) . 9♂♂, 2 subadult ♂♂, 56♀♀ (9 with oostegites, 14 brooding), 9 juveniles, 1 manca ( BMNH xxxx), Kanaal Gent-Terneuzen , Netherlands, 51° 18’55”N 03°49’32”E, 23 September 2008 (leg. Ton van Haaren) .

Diagnosis

Antennal peduncle article 2 without distal tuft of setae; antennal peduncle articles 2 and 3 without dorsal flange; lacinia mobilis of right mandible parallel-sided, with three slight denticulations; lacinia mobilis of left mandible wider than long; maxilliped palp distal article less than twice as long as wide; eight distal spines on maxillular endite, four distal setae on maxilliped endite; no proximal seta-bearing tubercle on female chela fixed finger; carpi of pereopods 2 and 4 with five distal spines; pereopod 6 with ventrodistal row of four leaf-like spines on propodus; pleopod 1 basis outer margin with four setae; uropod basis in female as long as first uropod segment. Male carapace 1.3 times as long as basal width; one proximal ventral apophysis on male cheliped carpus, ventral apophyses on male cheliped merus present.

Description of brooding female holotype

Body ( Figure 1A ) 5.3 times as long as wide, dorsally with black mottling on all tergal surfaces as well as on antennule and cheliped (in preserved material); length of holotype 2.7 mm. Cephalothorax tapering towards anterior, 1.1 times as long as wide, with slight rounded frons but no rostrum, eyes present, pigmented. Cephalothorax just shorter than pereonites 1–3 together. Pereonites, rounded laterally, pereonites 1 and 2 with four dorsal setae towards anterior of pereonite, and paired dorsolateral setae on remaining pereonites; pereonite 1 shortest, one-quarter as long as cephalothorax, pereonites 2 and 3, respectively, 1.3 and 1.8 times as long as pereonite 1; pereonites 4 and 5 subequal, longest, 2.3 times as long as pereonite 1, pereonite 6 just longer than pereonite 3 (all pereonites, respectively, 3.3, 2.5, 1.9, 1.5, 1.3 and 1.4 times as wide as long). Pleon of four free pleonites; pleonites 1–3 with transverse latero-dorsal rows of setae not reaching centre of pereonite, less well developed on pleonite 3; pleonites 1 and 2 one-third as long as pereonite 4, and 3.8 times as wide as long; pleonite 4 shorter and narrower, with four dorsal setae towards anterior. Pleotelson semicircular, 1.6 times as wide as long, with single mid-lateral seta, shorter subdistal dorsal seta and paired distal setae on each side.

Antennule ( Figure 2A ) with proximal peduncle article 2.4 times as long as wide with four simple distal setae and mid-length tuft of penicillate setae; second article 0.4 times as long as first with outer distal tuft and inner distal pair of simple setae and one distal penicillate seta; third article three-quarters length of second article, with two simple distal setae; distal segment very small, with eight distal setae and one aesthetasc.

Antenna ( Figure 2B ) with first peduncle article naked, compact, half length of second; second article 1.2 times as long as wide with two simple distal setae; third article just longer than first, wider than long, naked; fourth article longest, twice as long as first article and 1.6 times as long as wide, with one simple distal seta; fifth article 0.8 times as long as fourth, with two simple and one penicillate distal setae; distal segment very small with eight distal setae.

Labrum ( Figure 2C ) squared, distally setose. Left mandible ( Figure 2D ) with wide, robust, distally denticulate lacinia mobilis and adjacent seta, right mandible ( Figure 2E ) with narrow, parallel-sided distally crenulate lacinia mobilis; pars molaris of each mandible robust, rugose. Labium ( Figure 2H ) wide, all lobes finely setose distally. Maxillule ( Figure 2F ) with eight distal spines, finely setose outer margin. Maxilla ( Figure 2G ) simple, ovoid, naked. Maxilliped ( Figure 2I ) coxa with single inner seta; basis with single seta exceeding proximal margin of palp article 2; proximal palp article naked, second palp article with five simple inner setae but no outer seta; third article with nine simple inner setae in two rows; fourth article 1.9 times as long as wide, with eight distal and one outer subdistal simple setae. Maxilliped endites ( Figure 2J ) with two simple and two longer coarsely plumose setae. Epignath ( Figure 2K ) typical of genus, elongate with distal spine and finely setose margin.

Cheliped ( Figure 3A ) comparatively stout, basis 1.7 times as long as wide with ventrodistal seta, sidepiece naked; merus ventrally with single subdistal seta and marginal invagination; carpus 1.4 times as long as wide, with single dorsal setae in proximal and distal halves, paired midventral setae; propodus 0.8 times as long as wide, with single ventral seta, two inner distal setae at dactylus attachment; fixed finger with outer distal tubercle bearing four setae, two inner distal setae, cutting edge distally expanded into lobate lamella and with one simple seta in proximal half; dactylus with three fine setae along cutting edge.

Pereopod 1 ( Figure 3B ) coxa with seta but no apophysis; ischiobasis slender, 3.8 times as long as wide, with one simple and one penicillate seta dorsoproximally; merus 0.3 times length of ischiobasis with fine ventrodistal seta; carpus 1.4 times as long as merus, with two simple dorsal setae and one ventrodistal seta; propodus 1.5 times as long as carpus, with one mid-dorsal, one dorsodistal and one ventrodistal simple setae; dactylus 1.5 times as long as unguis, both together 0.8 times as long as propodus. Pereopod 2 ( Figure 3C ) ischiobasis 3.1 times as long as wide with single dorsoproximal and ventrodistal setae; merus 0.4 times as long as ischiobasis with ventrodistal seta and short tooth-like spine; carpus compact, shorter than merus, with dorsodistal seta and three anterodistal and two posterodistal short tooth-like spines ( Figure 3C’ ); propodus 1.6 times as long as carpus, with single dorsodistal and ventrodistal setae; dactylus plus unguis as long as carpus. Pereopod 3 similar to pereopod 2 but slightly smaller.

Pereopod 4 ( Figure 3D ) ischiobasis three times as long as wide, with single ventrodistal seta; merus 0.4 times as long as ischiobasis, with paired subdistal ventral short spines; carpus 0.8 times as long as merus, with dorsodistal seta and crown of three anterodistal and two posterodistal short tooth-like spines; propodus 1.3 times as long as carpus, with two simple and none penicillate distal setae; dactylus and unguis fused into a claw, curved, with lateral comb of twelve spinules. Pereopod 5 as pereopod 4. Pereopod 6 ( Figure 3E ) as pereopod 4, but propodus with ventrodistal row of four leaf-like spines, and simple distal setae dorsally placed.

Pleopods 1 and 2 (see van Haaren & Soors 2009, fig. 3) basis with single seta on inner margin and four outer plumose setae, pleopod 3 without seta on inner margin ( Figure 3F ); exopod with 20 plumose setae along outer edge; endopod with one inner and nine outer plumose setae, distally with shorter, stout, articulate seta.

Uropod ( Figure 3G ) of three segments plus basis, second segment 1.3 times as long as first, other segments and basis subequal in length.

Description of male

Body ( Figure 1B ) of similar size, proportion and pigmentation to that of female, but cephalothorax anteriorly narrowed, 1.3 times as long as wide. Antennule ( Figure 4A ) more elongate than that of female, proximal peduncle article four times as long as wide; distal segment with four simple setae and three aesthetascs. Antenna ( Figure 4B ) more slender than that of female; second peduncle article three times as long as first; fourth article 3.5 times as long as first and four times as long as wide, with two distal setae.

Cheliped ( Figure 4C ) more robust than that of female, basis 1.2 times as long as wide with one ventrodistal seta; merus with mid-ventral seta and two marginal ventral apophyses; carpus 1.1 times as long as wide with two mid-ventral setae and innerventroproximal rounded apophysis; propodus massive, 0.7 times as long as wide.

Subadult male

Habitus like that of female, carapace little longer than wide, antennule intermediate between those of female and mature male, cheliped ( Figure 4D ) more compact than that of female but without inner-proximal carpal apophysis.

Body lengths

Brooding females 1.7–2.7 mm (holotype); females with oostegites 1.9–2 mm; males 1.5–2.7 mm (allotype).

Etymology

Named after Ton van Haaren, who first reported this species, and who supplied some of the material.

Remarks

This species has already been described to some extent (as Sinelobus stanfordi ) by van Haaren and Soors (2009), who gave details of other records, sampling sites, and salinities, as well as photographs of both male and female specimens. Salinities at the sampling sites listed in van Haaren and Soors (2009) ranged from 3.1 to 13.2‰.

This species has an unusually short distal article to the maxilliped palp (less than twice as long as wide, compared with at least 2.5 times as long as wide in all other species where known), and has ventral apophyses on the male cheliped merus, unlike all three species described previously.

Type locality: Hoek van Holland, Netherlands.

Figures

Figure 1. Sinelobus vanhaareni sp. nov., (A) holotype female, dorsal; (B) allotype male, dorsal. Scale bar 1 mm.

Figure 2. Sinelobus vanhaareni sp. nov., female: (A) left antennule; (B) left antenna; (C) labrum; (D) left mandible, with detail of lacinia mobilis; (E) right mandible, with detail of lacinia mobilis; (F) maxillule; (G) maxilla; (H) labium; (I) maxilliped; (J) maxilliped endite; (K) epignath. Scale bar 0.2 mm.

Figure 3. Sinelobus vanhaareni sp. nov., female: (A) left cheliped; (B) left pereopod 1; (C) left pereopod 2, with (C’) distal spination of carpus; (D) left pereopod 4; (E) right pereopod 6; (F) third pleopod (most setae shown only by their bases; plumosity of all setae omitted); (G) pleotelson and right uropod. Scale bar 0.2 mm.

Figure 4. Sinelobus vanhaareni sp. nov., male: (A) right antennule; (B) right antenna; (C) left cheliped; (D) left cheliped of subadult male. Scale bar 0.2 mm.