Typhlotanais ischnochela, Segadilha & Serejo, 2022

Segadilha, Juliana L. & Serejo, Cristiana S., 2022, New insights gained from museum collections: new deep-sea species of Typhlotanais (Tanaidacea, Typhlotanaidae) from Brazil, European Journal of Taxonomy 820, pp. 1-54 : 27-35

Typhlotanais ischnochela sp. nov.

urn:lsid:zoobank.org:act:520C60FB-5B81-401E-97E2-BFD9B8EA5A27

Figs. 11–13 , 21

Diagnosis

Antennule longer than carapace; article-1 slender, about 6.0× L:W; article-3 long, about 6.0 × L:W. Antenna article-4 slender, about 9.2× L:W. Cheliped carpus elongate, more than 4.0× L:W. Cheliped propodus about 4.0× L:W. Pereopods 4–6 carpus with prickly tubercles half length of carpus, surrounded by spines. Uropod exopod one-articled, 0.7 × as long as endopod, with row of minute spines along inner margin; endopod one-articled; 6.6 × L:W.

Etymology

From the Greek ‘ ischnos ’ (‘thin’) and the Latin ‘ chela ’ (‘claw’), alluding to the slender cheliped. It is a compound Greek+ Latin noun in the nominative case used in apposition.

Material examined

Holotype

BRAZIL – Espírito Santo State • neuter, length 2.6 mm; Espírito Santo Basin , stn AMB 12 CAND 4 R 1; 19.5308° S, 39.0512° W; depth 171 m; 9 Dec. 2011; MZUSP 37681 .

Paratypes

BRAZIL – Rio de Janeiro State • 1 neuter (dissected), length 2.3 mm; Campos Basin , stn HAB 7 D6 R3 ; 23.5588° S, 40.4460° W; depth 396.2 m; 9 Jul. 2008; MZUSP 34428 • 1 neuter; Campos Basin , stn HAB 4 CANG 7 R2 ; 21.9367° S, 39.9625° W; depth 720 m; 7 Feb. 2009; MZUSP 32851 • 1 neuter; Campos Basin , stn HAB 7 A6 R1 ; 23.6330° S, 41.3290° W; depth 388.9 m; 3 Jul. 2008; MZUSP 32859 • 2 neuters; Campos Basin , stn HAB 7 F7 R2 ; 22.3317° S, 40.0357° W; depth 703.9 m; 7 Jul. 2008; MZUSP 32860 • 1 neuter; Campos Basin , stn HAB 3 H10 R1 ; 23.6849° S, 41.2706° W; depth 1898.7 m; 14 May 2008; MZUSP 32880 • 1 neuter; Campos Basin , stn HAB 11 E5 R2 ; 22.3942° S, 40.3447° W; depth 153 m; 23 Feb. 2009; MZUSP 32888 • 1 neuter; Campos Basin , stn HAB 11 F4 R2 ; 22.2091° S, 40.2236° W; depth 99 m; 25 Feb. 2009; MZUSP 32889 • 2 neuters; Campos Basin , stn HAB 11 G4 R2 ; 22.0694° S, 40.1183° W; depth 91 m; 25 Feb. 2009; MZUSP 32890 • 3 neuters; Campos Basin , stn HAB 4 CANG 7 R1 ; 21.9367° S, 39.9625° W; depth 720 m; 7 Feb. 2009; MZUSP 32891 • 1 neuter; Campos Basin , stn HAB 9 G7 R1 ; 22.1277° S, 39.9042° W; depth 680 m; 8 Feb. 2009; MZUSP 32907 • 1 neuter; Campos Basin , stn HAB 11 C4 ; 22.8660° S, 40.9597° W; depth 92 m; 22 Feb. 2009; MZUSP 34427 • 1 neuter; Campos Basin , stn HAB 11 G4 ; 22.0694° S, 40.1183° W; depth 91 m; 25 Feb. 2009; MZUSP 34430 • 5 neuters; Campos Basin , stn HAB 16 B4 ; 23.1681° S, 41.0518° W; depth 107 m; 2 Jul. 2009; MZUSP 34431 • 1 neuter; Campos Basin , stn HAB 9 CANG 7 ; 21.9367° S, 39.9625° W; depth 720 m; 7 Feb. 2009; MZUSP 34432 • 1 neuter; Campos Basin , stn HAB 8 D7 ; 22.6070° S, 40.3752° W; depth 695.5 m; 29 Jan. 2009; MZUSP 34434 • 1 neuter; Campos Basin , stn HAB 16 E4 ; 22.2951° S, 40.4499° W; depth 103 m; 4 Jul. 2009; MZUSP 34445 • 2 neuters; Campos Basin , stn HAB 13 D3 ; 22.3260° S, 40.6220° W; depth 75 m; 15 Mar. 2009; MZUSP 34450 • 1 neuter; Campos Basin , stn HAB 16 E5 ; 22.3942° S, 40.3450° W; depth 149 m; 4 Jul. 2009; MZUSP 34451 • 4 neuters; Campos Basin , stn RZEE #6750 ; 23.6680° S, 42.5300° W; depth 162 m; 16 Feb. 1998; MNRJ 19883 • 3 neuters; Campos Basin , stn RZEE #6762 ; 23.4367° S, 42.2637° W; depth 145 m; 28 Feb. 1998; MNRJ 19887 • 1 neuter; Campos Basin , stn RZEE #1 ; 20.8333° S, 39.2333° W; depth 83 m; 15 Jun. 2002; MNRJ 26488 • 2 neuters; Campos Basin , stn AC #25 ; 22.0959° S, 39.7654° W; depth 1730 m; 9 May 2002; MNRJ 26499 • 1 neuter; Campos Basin , stn OP #54 ; 21.9549° S, 39.9336° W; depth 750 m; 12 Dec. 2002; MNRJ 27358 • 1 neuter; Campos Basin , stn P-27 #07 R2 ; 22.3860° S, 37.8466° W; depth 535 m; Set. 2014; MNRJ 30137 . – Espírito Santo State • 3 neuters; Espírito Santo Basin , stn RZEE #1 C6 R2 ; 19.7600° S, 39.5181° W; depth 100 m; 21 Jun. 2002; MNRJ 26481 • 1 neuter; Espírito Santo Basin, stn RZEE #Y3 ; 21.1653° S, 40.3286° W; depth 46 m; 16 Jun. 2002; MNRJ 26487 • 1 neuter; Espírito Santo Basin , stn AC #41C ; 21.2167° S, 40.2167° W; depth 1000 m; 20 Jul. 2001; MNRJ 18360 .

Additional material (lost in the fire)

BRAZIL – Rio de Janeiro State • 3 neuters; Campos Basin , stn HAB 13 H4 R2 ; 21.7150° S, 40.1712° W; depth 98 m; 9 Mar. 2009; MZUSP 22881 • 2 neuters; 2 juveniles; Campos Basin , stn HAB 11 E5 R2 ; 22.3942° S, 40.3447° W; depth 153 m; 23 Feb. 2009; MZUSP 22899 • 1 neuter; Campos Basin , stn HAB 7 D6 R2 ; 23.5588° S, 40.4460° W; depth 396.2 m; 9 Jul. 2008; MZUSP 32871 • 3 juveniles; stn HAB 9 CANG 7 R1 ; 21.9367° S, 39.9625° W; depth 720 m; 7 Feb. 2009; MZUSP 32905 • 1 neuter; Campos Basin , stn HAB 16 B4 R2 ; 23.1681° S, 41.0518° W; depth 107 m; 2 Jul. 2009; MZUSP 34425 • 1 neuter; Campos Basin , stn HAB 13 D3 ; 22.3260° S, 40.6220° W; depth 75 m; 15 Mar. 2009; MZUSP 34433 • 1 neuter; Campos Basin, stn HAB 13 Foz 43 ; 22.2050° S, 40.2440° W; depth 97 m; 15 Mar. 2009; MZUSP 34435 • 1 neuter; Campos Basin , stn HAB 13 H5 ; 21.7092° S, 40.1517° W; depth 147 m; 9 Mar. 2009; MZUSP 34440 • 1 juvenile; Campos Basin , stn HAB 6 A7 R2 ; 23.6557° S, 41.3078° W; depth 693.7 m; 23 Jun. 2008; MZUSP 34441 • 1 neuter; Campos Basin , stn HAB 7 D6 R2 ; 23.5588° S, 40.4460° W; depth 396.2 m; 9 Jul. 2008; MZUSP 34444 • 1 neuter; Campos Basin , stn HAB 7 A6 R3 ; 23.6330° S, 41.3290° W; depth 388.9 m; 3 Jul. 2008; MZUSP 34452 • 2 neuters; 1 juvenile; Campos Basin , stn HAB 9 I 7 R2 ; 21.1867° S, 40.2145° W; depth 680 m; 4 Feb. 2009; MZUSP 38014 • 1 neuter; Campos Basin , stn A #10 R1 ; 23.3326° S, 41.3018° W; depth 120 m; 15 Jan. 2016; MOUFPE 15879 • 1 neuter; Campos Basin , stn B #1 R1 ; 23.2828° S, 41.2041° W; depth 120 m; 15 Jan. 2016; MOUFPE 15881 • 1 neuter; Campos Basin , stn B #7 R1 ; 23.3012° S, 41.2092° W; depth 120 m; 15 Jan. 2016; MOUFPE 15882 • 7 neuters; Campos Basin , stn B #3 R 3; 23.2925° S, 41.2092° W; depth 120 m; 15 Jan. 2016; MOUFPE 15889 • 1 neuter; Campos Basin , stn B #2 R1 ; 23.2907° S, 41.2063° W; depth 120 m; 15 Jan. 2016; MOUFPE 15895 • 1 neuter; Campos Basin , stn B #3 R1 ; 23.2925° S, 41.2092° W; depth 120 m; 15 Jan. 2016; MOUFPE 15899 • 1 neuter; Campos Basin , stn A #8 R2 ; 23.3462° S, 41.3055° W; depth 120 m; 15 Jan. 2016; MOUFPE 15902 • 2 neuters; Campos Basin , stn B #1 R1 ; 23.2828° S, 41.2041° W; depth 120 m; 15 Jan. 2016; MOUFPE 15905 • 2 neuters; Campos Basin , stn B #4 R2 ; 23.2942° S, 41.2073° W; depth 120 m; 15 Jan. 2016; MOUFPE 15906 • 2 neuters; Campos Basin , stn B #14 R 1; 23.2946° S, 41.2135° W; depth 120 m; 15 Jan. 2016; MOUFPE 15907 • 2 neuters; Campos Basin , stn RZEE #6759 ; 23.3333° S, 41.3667° W; depth 110 m; 28 Feb. 1998; MNRJ 19878 • 1 neuter; Campos Basin , stn RZEE #6744 ; 23.8583° S, 42.8317° W; depth 254 m; 15 Feb. 1998; MNRJ 19892 . – Espírito Santo State • 2 neuters; Espírito Santo Basin , stn AMB 12 CAND 4 R1 ; 19.5308° S, 39.0512° W; depth 171 m; 9 Dec. 2011; MZUSP 38965 .

Description

Paratypes (MZUSP 34444, MZUSP 34428 dissected)

BODY ( Fig. 11A–B ). Slender, about 7.6 × L:W. Cephalothorax tappering forward, with rounded lateral margins, 1.3× L:W, 3.9× as long as pereonite-1, naked; eyes absent.

PEREONITES 1–6. All pereonites rectangular, wider than long, with lateral margin gently convex; pereonites 1–3 with setae on proximal margin, pereonites 4–6 with lateral setae; pereonite-1 shortest, 0.3 × L:W; pereonite-2 0.6× L:W; pereonite-3 0.7× L:W; pereonite-4 longest, about 0.9 × L:W; pereonite-5 0.7× L:W; pereonite-6 0.5× L:W.

PLEON ( Fig. 11A–B ). 0.2× TBL, with five subequal pleonites, together as long as carapace, with lateral setae. Pleotelson distally rounded, about 0.5 × L:W, with one pair of setae distally and lateral seta on each side.

ANTENNULE ( Fig. 11C ). As long as cephalothorax, with three articles; article-1 slender, about 0.6× TL, 6.1× L:W, with two simple middle setae and four penicillate setae, and with two simple and four penicillate setae distally; article-2 twice L:W, 0.2× as long as article-1, with simple and penicillate distal setae; article-3 long, about 5.8 × L:W, 2.3× as long as article-2, with six simple (two very long, almost as long as antennule TL) and penicillate terminal setae and aestethasc.

ANTENNA ( Fig. 11D ). Of six articles, article-1 naked, fused with body; article-2 slightly longer than wide, with simple distal seta; article-3 × L:W, 1.2 × as long as article-2, with small distal spines; article-4 slender, about 9.2 × L:W, 5.8 × as long as article-3, with two simple and four penicillate setae distally; article-5 5.0× L:W, 0.3× as long as article-4, with distal seta; article-6 minute, with four terminal setae.

LABRUM ( Fig. 12A ). Rounded, hood-shaped, distally covered by minute setae. Mandible ( Fig. 12B–C ) molar broad with blunt teeth and two spines. Left mandible ( Fig. 12B ) lacinia mobilis well developed, gently undulated; right mandible ( Fig. 12C ) as left, but without lacinia mobilis. Maxillule ( Fig. 12D ) endite with seven to eight terminal spines and microtrichia; palp with serrate seta (broken off during dissection). Epignath ( Fig. 12E ) elongate, linguiform, naked. Labium ( Fig. 12F ) with distolateral corner finely setose; outer lobe membranous, finely setose. Maxilliped ( Fig. 12G ) sparsely setose; basis with simple seta not reaching distal margin of endites; endites unfused, with two simple setae, one large gustatory cusp on distal edge and microtrichia on outer corner; palp with four articles; article-1 triangular, naked; article-2 with two simple and one robust serrated setae on inner margin, and simple setae on outer margin; article-3 with four simple inner setae; article-4 with five robust serrated inner setae and simple subdistal outer seta.

CHELIPED ( Fig. 12H ). Basis distally rounded, 2.1× L:W, with simple dorsoproximal seta; merus subtriangular, with ventral seta; carpus 4.3× L:W, with two long (one almost 3.0× longer than the other) and minute ventral setae; and five minute setae along dorsal margin; propodus about as long as carpus, 3.9× L:W, with penicillate and simple setae near dactylus insertion (one on inner and one on outer side); fixed finger with two simple ventral setae; cutting edge with three setae and margin undulated distally; dactylus as long as fixed finger, with minute dorsoproximal seta.

PEREOPOD-1 ( Fig. 13A ). Walking type; slender, longer than others; coxa with apophysis and seta; basis elongate, 5.6× L:W, with simple and penicillate dorsoproximal and simple middorsal setae; ischium with simple ventral seta; merus 3.3 × L:W, with simple ventrodistal seta; carpus 3.1× L:W, about as long as merus, with five simple distal setae; propodus 3.7× L:W, as long as carpus, with two simple dorsodistal setae and simple ventral seta; dactylus half as long as unguis, with seta shorter than unguis; dactylus and unguis together about as long as propodus.

PEREOPOD-2 ( Fig. 13B ). Walking type; coxa with apophysis and seta; basis elongate 4.0× L:W, with penicillate dorsoproximal and simple middorsal setae; ischium with simple ventral seta; merus 1.4× L:W, with two simple ventrodistal setae; carpus 1.4× L:W, about as long as merus, with five simple distal setae and minute ventrodistal spine; propodus 3.1× L:W, subequal to merus and carpus combined, with two dorsodistal and one simple ventrodistal setae; dactylus 0.5 × as long as unguis, with seta; dactylus and unguis together about 0.5 × as long as propodus.

PEREOPOD-3 ( Fig. 13C ). Similar to pereopod-2, except basis with two simple and one penicillate setae dorsally; merus with simple ventrodistal seta.

PEREOPOD-4 ( Fig. 13D, I ). Clinging type; coxa absent; basis robust twice L:W, with penicillate ventral and simple dorsal setae; ischium short, with two setae; merus triangular, about 1.6× L:W, with two distoventral spines and microtrichia; carpus 1.7× L:W, with robust spine dorsodistally and prickly tubercles half length of carpus, surrounded by spines ( Fig. 13I ); propodus 3.6 × L:W, with robust dorsodistal seta, two subdistal ventral spines and numerous microtrichia; dactylus with microtrichia ventrally; dactylus 2.6× as long as unguis; unguis simple, both combined as long as propodus.

PEREOPOD-5 ( Fig. 13E ). Similar to pereopod-4, except basis with one simple and two long penicillate ventral setae; propodus with penicillate middorsal seta.

PEREOPOD-6 ( Fig. 13F ). Similar to pereopod-4, except basis with single penicillate ventral seta; carpus with simple distal setae; propodus with three robust distodorsal serrate setae; dactylus and unguis combined shorter than propodus.

PLEOPOD ( Fig. 13G ). All pleopods similar; basal article naked; exopod with ten plumose setae on outer margin and with plumose seta on inner margin; endopod with sixteen plumose setae on outer margin. Large gap between proximal seta and others in both rami.

UROPOD ( Fig. 13H–J ). 1.6× as long as pleotelson; basis 1.5 × L:W, naked; exopod one-articled, 0.7× as long as endopod, with simple medial seta and microtrichia along inner margin, tipped by stout and simple setae and microtrichia along inner margin ( Fig. 13J ); endopod one-articled; 6.6× L:W, with penicillate seta medially, tipped by one stout, four simple and one penicillate setae.

Distribution

Brazil: Campos Basin, Rio de Janeiro and Espírito Santo Basin, Espírito Santo. Occurring from the continental shelf until the lower slope, depth range from 46 to 1898.7 m ( Fig. 21 ).

Remarks

Typhlotanais ischnochela sp. nov. is part of the ‘ greenwichensis ’ group by the presence of a spur on pereopods 1–3 coxae ( Table 3 ). The new species resembles T. herthio in general habitus, slender antennule and cheliped, and uropod with microtrichia on exopod lateral margin ( Table 3 ), However it differs from T. herthio by (1) cheliped carpus very slender, more than 4.0 × L:W (stouter in T. herthio , 2.8× L:W); (2) cheliped propodus slender, about 4.0 × L:W (3.4 × L:W in T. herthio ); (3) pereopods 1–3 basis with at most three setae (more than six in T. herthio ); and (4) pereopods 1–3 carpus with at most five setae (seven or more in T. herthio ).

Typhlotanais ischnochela sp. nov. differs from T. greenwichensis and T. messinensis by (1) antennule article-1 very slender, about 6.0× L:W ( T. messinensis 3.0× and T. greenwichensis 4.0 × L:W); (2) antennule article-3 long, about 6.0 × L:W ( T. messinensis 4.4× and T. greenwichensis 3.0× L:W); (3) antenna article-4 slender, about ninex L:W ( T. messinensis 4.0× and T. greenwichensis 7.0× L:W); (4) cheliped carpus elongate, more than 4.0 × L:W ( T. messinensis 2.5 × and T. greenwichensis 3.0× L:W); (5) cheliped propodus long, about 4.0 × L:W ( T. messinensis 2.8× and T. greenwichensis 3.3× L:W); and (6) uropod exopod with microtrichia along inner margin.

“ spinicauda ” group

Species included

Typhlotanais spinicauda Hansen, 1913 ; Typhlotanais squamiger Błażewicz-Paszkowycz, 2007 ; T. priscilae sp. nov.

Figures

Fig. 11. Typhlotanais ischnochela sp. nov. A–B. ♀ (MZUSP 34444). A. Dorsal view. B. Lateral view. C–D. Paratype (MZUSP 34428), ♀, dissected. C. Antennule. D. Antenna. Scale bars: A–B = 1 mm; C–D = 0.1 mm.

Fig. 12. Typhlotanais ischnochela sp. nov., paratype (MZUSP 34428), ♀, dissected. A. Labrum. B. Left mandible. C. Right mandible. D. Maxillule. E. Epignath. F. Labium. G. Maxilliped. H. Cheliped. Scale bar = 0.1 mm.

Fig. 13. Typhlotanais ischnochelasp. nov. A–H. Paratype (MZUSP 34428), ♀, dissected.A–F. Pereopods 1–6. G. Pleopod. H. Uropod. I–J. Additional material, ♀ (MZUSP 38014). I. Detail of pereopod prickly tubercles surrounded by spines. J. Detail of uropod microtrichia. Scale bars: A–H = 0.1 mm; I = 0.01 mm; J = 0.02 mm.

Fig. 21. Bathymetric range of species of Typhlotanais along the Brazilian coast (19° S–24° S) based on samples listed in Table 1.