Typhlotanais bolarticulus, 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 : 21-27

Typhlotanais bolarticulus sp. nov.

urn:lsid:zoobank.org:act:7FDD8AC1-4632-4343-B6B1-E40009966ACC

Figs. 8–10 , 21

Diagnosis

Body short, about 5.0× L:W; antennule with all setae stout; antenna article-2 globose, 1.6× wider than article-3; conspicuous spines on pereopod-2 basis and less conspicuous on pereopod-1 and pereopod-3 basis; pereopods 2–3 dactylus with very long seta, more than 3.0× as long as unguis; pereopods 4–6 propodus with distal setae longer than dactylus and unguis combined; unguis simple; pereopod-6 propodus with several small spines along the article.

Etymology

From the Latin ‘ bola ’ (Latin), meaning ‘ball’, ‘globe’. The name reflects the antenna article-2, which is globose and enlarged dorsally.

Material examined

Holotype

BRAZIL – Rio de Janeiro State • neuter, length 1.7 mm; Campos Basin , stn HAB 3 H9 ; 21.6555° S, 39.899° W; depth 1293.2 m; 13 May 2008; MZUSP 38973 .

Paratypes

BRAZIL – Rio de Janeiro State • 2 neuters (1 dissected), length 1.3 mm; Campos Basin , stn HAB 3 A8 R1 ; 23.6849° S, 41.2706° W; depth 986 m; 3 May 2008; MZUSP 32878 . – Espírito Santo State • 1 neuter; Espírito Santo Basin , stn AMB 11 B6 R2 ; 20.6000° S, 39.8596° W; depth 998 m; 8 Jan 2012; MZUSP 38963 • 1 neuter; Espírito Santo Basin , stn AMB 8 G7 R2 ; 19.0575° S, 37.8118° W; depth 1308 m; 30 Jan. 2012; MZUSP 38970 • 2 neuters; Espírito Santo Basin , stn AMB 3 E6 R1 ; 19.6685° S, 39.1214° W; depth 1035 m; 13 Dec. 2011; MZUSP 38975 • 1 neuter; Espírito Santo Basin , stn AMB 5 B7 R2 ; 21.0793° S, 40.0752° W; depth 1294 m; 31 Dec. 2011; MZUSP 38979 .

Additional material (lost in the fire)

BRAZIL – Rio de Janeiro State • 1 neuter; Campos Basin , stn HAB 3 H9 ; 21.6555° S, 39.899° W; depth 1293.2 m; 13 May 2008; MZUSP 34471 • 1 neuter; Campos Basin , stn RC #10 ; 21.9756° S, 39.8646° W; depth 1700 m; 8 Oct. 2001; MNRJ 18328 .

Description

Paratype (MZUSP 32878 dissected)

BODY ( Fig. 8A–B ). Short, about 5.0× L:W. Cephalothorax rounded L:W, 4.6 × as long as pereonite-1, naked; eyes absent.

PEREONITES 1–6. All pereonites rectangular, wider than long, with setae on lateral margin; pereonite-1 shortest, 0.2 × L:W, with three pairs of setae on proximal margin; pereonite-2 0.5× L:W; pereonite-3 0.5× L:W; pereonite-4 0.7× L:W; pereonite-5 0.7 × L:W; pereonite-6 0.5× L:W.

PLEON ( Fig. 8A–B ). 0.3× TBL, with four subequal pleonites, the last one slightly longer than others. Pleotelson trapezoidal 0.5× L:W, with three pairs of setae distally.

ANTENNULE ( Fig. 8C ). 1.2× as long as cephalothorax, with three articles; article-1 0.6 × TL, 2.5× L:W, with stout and penicillate setae distally; article-2 0.7× L:W, 0.2× as long as article-1, with two stout and penicillate distal setae; article-3 3.4 × L:W, 2.8× as long as article-2, with seven to eight stout terminal setae.

ANTENNA ( Fig. 8D ). Of six articles, article-1 with microtrichia, fused with body; article-2 once L:W, with a globose shape and numerous microtrichia, 1.6 × wider than article-3; article-3 about as long as wide, with long seta and numerous microtrichia; article-4 4.3× L:W, 3.3× as long as article-3, with two simple and three penicillate setae distally; article-5 2.4× L:W, 0.4× as long as article-4, with distal seta; article-6 minute with five simple terminal setae.

LABRUM ( Fig. 9A ) rounded, hood-shaped, distally covered by minute setae. Mandible ( Fig. 9B–C ) molar broad with prominent regular nodules. Left mandible ( Fig. 9B ) with microtrichia along the outer margin, incisor smooth, lacinia mobilis well developed, crenulate, with six lobes; right mandible ( Fig. 9C ) as left, but without microtrichia and lacinia mobilis. Maxillule ( Fig. 9D ) endite with eight terminal spines (one short); palp ( Fig. 9E ) with two distal setae. Labium ( Fig. 9F ) with distolateral corner finely setose; outer lobe membranous, finely setose. Maxilliped ( Fig. 9G ) sparsely setose; basis with simple seta not reaching distal margin of endites; endites unfused, with two small gustatory cusps and seta on distal edge and microtrichia on outer corner; palp with four articles; article-1 naked; article-2 with three inner setae (one simple, two serrated) and minute seta on outer margin; article-3 with four serrated inner setae; article-4 with five serrated inner setae and simple subdistal outer seta. Maxilla not observed. Epignath not observed.

CHELIPED ( Fig. 9H ). Basis distally rounded, stout, 1.7× L:W, with simple seta dorsally; merus subtriangular, with ventral seta; carpus stout 2.2× L:W, with two simple ventral setae and microtrichia and two minute dorsal setae; propodus about as long as carpus, 2.4× L:W, with two setae near dactylus insertion (one on inner and one on outer side) and microtrichia; fixed finger with two simple setae ventrally; cutting edge with two rod (similar size) and one simple setae; dactylus as long as fixed finger.

PEREOPOD-1 ( Fig. 10A ). Walking type; coxa with seta shorter than half length of basis; basis 3.1× L:W, with simple dorsal seta and numerous microtrichia; ischium with minute seta; merus stout, about as long as wide, with dorsodistal and ventrodistal setae; carpus 1.3× L:W, longer than merus, with four simple distal setae (one longer than half length of propodus) and numerous microtrichia; propodus twice L:W, 1.3 × as long as carpus, with three dorsodistal, one ventrodistal setae and numerous microtrichia; dactylus 0.6× as long as unguis, with seta as long as unguis; dactylus and unguis together 0.7× as long as propodus.

PEREOPOD-2 ( Fig. 10B ). Walking type; coxa with seta; basis stout 2.8× L:W, with two penicillate dorsoproximal setae and eleven small dorsal spines; ischium with small dorsal spine and ventral seta; merus about as long as wide, with dorsodistal and ventrodistal setae; carpus about as long as wide, with dorsodistal simple spine and ventrodistal subrounded spine; propodus 2.4 × L:W, as long as merus and carpus combined, with two dorsodistal (one longer than unguis) and minute ventrodistal spine; dactylus 0.7× as long as unguis, with robust seta 4.0 × as long as dactylus and unguis combined; dactylus and unguis together 0.5× as long as propodus.

PEREOPOD-3 ( Fig. 10C ). Similar to pereopod-2, except basis with two simple ventral setae and strong microtrichia on dorsal margin; ischium with ventral seta; merus with two ventrodistal setae; carpus with ventrodistal subrounded spine (bigger than in pereopod-2) and one ventrodistal seta; propodus with simple spine and short seta dorsodistally.

PEREOPOD-4 ( Fig. 10D ). Clinging type; coxa absent; basis robust 1.5 × L:W, with two long ventroproximal penicillate setae and simple dorsal seta; ischium with minute seta; merus triangular about as long as wide, with two spines ventrodistally (only one illustrated); carpus about 1.2× L:W, with robust spine dorsodistally and prickly tubercles more than half length of carpus; propodus 3.4× L:W, with one dorsodistal seta longer than unguis and two ventrodistal spines (only one illustrated); dactylus 4.7× as long as unguis, both combined 0.7× as long as propodus.

PEREOPOD-5 ( Fig. 10E ). Similar to pereopod-4, except basis twice L:W, with simple and two long penicillate ventral setae.

PEREOPOD-6 ( Fig. 10F ). Similar to pereopod-4, except basis 1.6× L:W, with only simple ventral seta; merus and carpus slightly longer than wide; carpus with dorsodistal seta; propodus 3.9× L:W, with numerous strong microtrichia on ventral and dorsal margins and three dorsodistal setae longer than unguis (one simple and two pectinate).

PLEOPOD ( Fig. 10G ). All pleopods similar; basal article naked; exopod with seven plumose setae on outer margin and with plumose seta on inner margin; endopod with twelve plumose setae on outer margin. Large gap between proximal seta and others in both rami.

UROPOD ( Fig. 10H ). 0.7 × as long as pleotelson; basis 1.3 × L:W, naked; exopod one-articled, 0.6× as long as endopod, with simple medial seta and tipped by stout and simple setae; endopod one-articled; 4.5× L:W, with two medial, one subdistal, and tipped by three simple and one penicillate setae.

Distribution

Brazil: Campos Basin, Rio de Janeiro and Espírito Santo Basin, Espírito Santo. Occurring on the lower slope, depth range from 986 to 1700 m ( Fig. 21 ).

Remarks

Typhlotanais bolarticulus sp. nov. is part of the Typhlotanais ‘ cornutus ’ group by the presence of short body (about 5.0 × L:W), compact chelae (carpus about twice L:W) and the presence of pereopods 4–6 propodus distal setae longer than dactylus and unguis combined. The new species is similar to species of Larsenotanais Błażewicz-Paszkowycz, 2007 by having a short body and simple unguis on pereopods 4–6, but it can be differentiated by the presence of short setae on the propodus of pereopods 4–6. Furthermore, the new species can be distinguished easily by its conspicuous spines by pereopod-2 basis and less conspicuous on pereopod-1 and pereopod-3 basis ( Table 2 ).

Among the family Typhlotanaidae , only Typhlotanais spinipes Kudinova-Pasternak, 1982 has spines on pereopods 2–6 basis and T. plicatus Kudinova-Pasternak, 1993 has on pereopods 4–6 basis. Typhlotanais bolarticulus sp. nov. differs from the first by (1) antennule longer than carapace, with short apical setae ( T. spinipes has antennule as long as carapace, with long setae as long as antennule); (2) pereopods 4–6 basis without spines and (3) uropods rami one-articled (two-articled in T. spinipes ); and from the second by pereonites 1–3 smooth, without corrugation. Other than these differences, Typhlotanais bolarticulus sp. nov. also has very long seta on dactylus of pereopods 2–3 (more than 3.0 × longer than unguis) and antenna article-2 presents a characteristic globose shape, 1.6× wider than article-3.

“ greenwichensis ” group

Species included

Typhlotanais greenwichensis Shiino, 1970 ; T. herthio Błażewicz-Paszkowycz & Bamber, 2012 ; T. messinensis Sars, 1882 ; T. ischnochela sp. nov.

Figures

Fig. 8. Typhlotanais bolarticulus sp. nov. A. ♀ (MNRJ 18328), dorsal view. B–D. Paratype (MZUSP 32878), ♀, dissected.B. Lateral view.C. Antennule.D. Antenna. Scale bars:A–B = 1 mm; C–D = 0.1 mm.

Fig. 9. Typhlotanais bolarticulus sp. nov., paratype (MZUSP 32878), ♀, dissected. A. Labrum. B. Left mandible. C. Right mandible. D. Maxillule. E. Maxillule palp. F. Labium. G. Maxilliped. H. Cheliped. Scale bar = 0.1 mm.

Fig. 10. Typhlotanais bolarticulus sp. nov., paratype (MZUSP 32878), ♀, dissected. A–F. Pereopods 1–6. G. Pleopod. H. Uropod. Scale bar = 0.1 mm.

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