A new Setacheres (Copepoda, Siphonostomatoida, Asterocheridae) associated with Ircinia felix (Duchassaing & Michelotti) (Porifera) from Brazil
Author
Borges, Camila C.
Author
Neves, Elizabeth G.
Author
Johnsson, Rodrigo
text
Zootaxa
2017
2017-12-08
4363
1
129
136
journal article
31209
10.11646/zootaxa.4363.1.6
9de5d1d2-370c-4827-8be4-e6867f2fa610
1175-5326
1096315
11B8EE0C-3811-4EB6-8B9C-1D89D7EFCE91
Setacheres portobarrensis
sp. nov.
(
Figs. 2–4
)
Material examined.
Holotype
adult female (
UFBA 3182
) and
paratype
adult female (
UFBA 3183
),
Porto da Barra Beach
(
13°00'14.01"S
,
038°32'3.14"W
),
Salvador
city,
Bahia
State
,
Brazil
, collected by C.
Bahia
and V. Queiroz on
4 August 2011
. Both specimens found associated with
Ircinia felix
.
Paratype
(
UFBA 3183
) dissected and mounted on slide.
Holotype
preserved in ethanol.
Description of female.
Mean body length (excluding caudal setae) 687 µm (686–688 µm) and mean body width 393 µm (390–395 µm) (
n
= 2). Body (
Fig. 2a
) cyclopiform, dorsoventrally flattened, prosome longer than wide, urosome cylindrical. Pedigerous somite 1 completely fused with cephalothorax to form cephalosome. Pedigerous somites 2–4 with posterolateral margins not projected posteriorly and slightly rounded. Pedigerous somite 3 longer than pedigerous somite 2. Pedigerous somite 4 smaller than third somite and larger than fifth somite.
Prosome 470 µm long and 386 µm wide. Length: width ratio = 1.2:1. Urosome (
Fig. 2b
) 4-segmented. Fifth pedigerous somite 32 µm long and 116 µm wide. Genital somite 79 µm long and maximum width 104 µm, length: width ratio = 0.7:1, vestigial leg 6 located midlaterally with thin seta, close to genital openings; setules located posteriorly to leg 6. Two postgenital somites, both wider than long (36 × 56, 38 × 55 µm, respectively), epimera directed posterolaterally; first postgenital somite armed with 2 spinules on outer margin, anal somite with 4 spinules along lateral margin. Prosome: urosome ratio = 2.2:1. Caudal rami (
Fig. 2b
) longer than wide, 25×22 µm. Length: width ratio 1.1:1 µm, armed with 6 setae. All setae on specimens broken.
Rostrum (
Fig. 2c
) wider than long (72 × 224 µm), triangular with rounded apex. Antennule (
Fig. 2d
) 295 µm long (not including setae), 21-segmented. Lengths of segments in proximal to distal order: 35, 9, 9, 8, 9, 7, 9, 14, 10, 5, 8, 17, 20, 19, 13, 20, 23, 26, 9, 10 and 7 µm. Segmental homologies as follows: 1(I)-2; 2(II)-2; 3(III)-2; 4(IV)-2; 5(V)-2; 6(VI)-2; 7(VII)-2; 8(VIII)-2; 9(IX–XII)-6; 10(XIII)-2; 11(XIV)-I+2, 12(XV)-2; 13(XVI)-2; 14(XVII)-2; 15(XVIII)-2; 16(XIX)-2; 17(XX)-2; 18 (XXI)-2+ Aesthetasc; 19(XXII–XXIII)-3; 20(XXIV–XXV)- 1; 21(XXVI–XXVIII)-5. Aesthetasc 72 μm long. Both setae from segments 1–3 and one seta from segment 8 with sparse setules distally.
Antenna (
Fig. 3a
) 192 µm long (including distal claw); coxa 14 µm long; basis 62 µm long with spinules along inner margin. Exopod 1-segmented, 8 µm long, with 2 apical setae and small subdistal seta; all setae naked. Endopod 3-segmented; first segment 56 µm long, unarmed, inner margin ornamented medially with row of spinules and armed distally with 3 large spinules; second segment 6 µm long, armed with single robust seta covered with setules; third segment 10 µm long, armed with 2 subdistal spiniform setae and distal claw (36 µm).
Oral cone (
Fig.2a
) 172 × 94 µm (length × width), reaching to insertion of maxilliped bases. Mandible (
Fig. 3b
) with 2-segmented palp, both segments slender and naked, measuring 26 and 25 µm long, respectively; second segment with 2 naked distal setae, longer seta twice as long as shorter seta. Mandibular stylet 128 µm long, distally acuminate, posteriorly to a subterminal serrated portion with 7 teeth and triangular distal end. Maxillule (
Fig. 3c
) bilobed, both lobes laterally naked; inner lobe 50 µm long, with 5 naked distal setae, one seta much smaller than others. Outer lobe 18 µm long, armed with 4 naked distal setae, one more robust than the others. Maxilla (
Fig.3d
) 230 µm long, syncoxa 95 µm long, with small tooth-like projection on outer margin plus tubular extension of maxillary gland opening and strongly curved distally claw.
Maxilliped (
Fig.3e
) 6-segmented, 246 µm long; syncoxa 51 µm long with naked seta on inner margin and minute tooth-like projection on outer margin; basis 90 µm long, with subdistal row of setules and 2 small rows of spinules on inner and outer margins, respectively. Endopod 4-segmented, segments measuring 22, 9, 12 and 25 µm long, respectively; first and second segments naked, third segment with naked seta; fourth segment with spiniform serrate seta, close to distal curved claw-like element 46 µm long, with spinules on inner margin approximately reaching midlength.
Legs 1−4 (
Figs. 4a −d
) biramous, with 3-segmented rami. Armature formula as follows:
coxa basis exopod endopod
leg 1 0–1 1–1
I–1
;
I–1
; III,4 0–1; 0–2; 1,2,3
leg 2 0–1 1–0
I–1
;
I–1
; III,I,4 0–1; 0–2; 1,2,3
leg 3 0–1 1–0
I–1
;
I–1
; III,1,4 0–1; 0–2; 1,2,3
leg 4 0–1 1–0
I–1
;
I–1
; III,I,4 0-1; 0–2; 1,1+I,2
FIGURE 2.
Setacheres portobarren
sis
sp. nov.
female (paratype: UFBA 3183). a, body, dorsal view; b, rostrum; c, urosome; d, antennule. Scale bars: a = 125 µm; b = 50 µm; c = 70 µm; d = 50 µm.
FIGURE 3.
Setacheres portobarrensis
sp. nov.
female (paratype: UFBA 3183). a, antenna, arrows indicating spine-like setae close to distal claw on third endopodal segment; b, mandible, arrow indicating mandibular stylet with subterminal serrated portion and triangular distal end; c, maxillule, arrow indicating very thick, claw-like bristle on outer lobe; d, maxilla; e, maxilliped. Scale bars: a–e = 50 µm.
FIGURE 4.
Setacheres portobarrensis
sp. nov.
female (paratype: UFBA 3183). a, leg 1; b, leg 2; c, leg 3; d, leg 4; e, leg 5. Scale bars: a–d = 50 µm; e = 40 µm.
All legs with small spinules on outer margin of coxa, legs 2 and 3 each with a single spinule, leg 4 with 4 spinules and leg 1 with 2 rows of spinules. Legs 2 - 4 each with long setules along outer margin of endopod. Outer margins of most exopodal segments covered with small spinules. First exopodal segment of leg 1 bearing large spine reaching insertion of proximalmost spine of third exopodal segment. Second segment with tiny spine, smaller than adjacent tooth-like projection (
Fig. 4a
). Leg 3 with distal seta on third exopodal segment, instead of spine (
Fig. 4c
). Leg 4 with distal spine on third endopodal segment (
Fig. 4d
). Leg 5 (
Fig.4e
) with longer spinules on both margins, with 3 naked distal setae.
Male.
Unknown.
Type
locality.
Porto da Barra Beach
(
13°0'14.01"S
,
38°32'3.14"W
),
Salvador
city,
Bahia
State,
Brazil
.
Etymology.
The name “
portobarrensis
” refers to the
type
locality of the new species, Porto da Barra Beach, in
Salvador
city,
Bahia
State,
Brazil
.
Remarks.
In a recent study,
Johnsson
et al.
(2016)
erected the new genus,
Setacheres
in order to accommodate some
Asterocheres
that were previously considered as
species inquirendae
(
Kim, 2010
). The main character shared by the species included in the new genus is the presence of 2 distal setae on the third endopodal segment of leg 3, instead of a seta and a spine. Considering the new species described here, the genus
Setacheres
now contains 10 species; they can be separated into three different groups based on the number of free segments posterior to the ancestral antennulary segment XXI, which can range from 1 to 3.
Setacheres portobarrensis
sp. nov.
possesses a 21-segmented antennule, with 3 free segments distally, after the aesthetasc. An identical condition is observed in
S. eudistomus
Johnsson,
Bahia
& Neves, 2016
and
S. lunatus
Johnsson, 1998
, while
S. paraboecki
Johnsson, 1998
, despite showing 3 free distal segments, has a 20-segmented antennule, resulting from a fusion of segments in the mid-region of the antennule (
Johnsson 1998
;
Johnsson
et al
. 2016
).
Setacheres portobarrensis
sp. nov.
also differs from these two Brazilian species in the third exopodal segment of leg 3, which has a distal seta (III,1,4) instead of a spine (III,I,4) (Johnsson 1 998;
Johnsson
et al
. 2016
). Some other species of the genus with the same distal pattern are
S. spinopaulus
Johnsson, 1998
,
S. unicus
Johnsson, 2001
,
S. abrolhensis
Johnsson, 1998
, and
S. paraboecki
Johnsson, 1998
but none of them has a 21-segmented antennule (
Johnsson 1998
;
Johnsson
et al
. 2001
). In addition,
S. portobarrensis
sp. nov.
shows many unique features such as: 1) spine-like setae close to the distal claw on the third endopodal segment of the antenna (arrows in
Fig. 3a
); 2) mandibular stylet with subterminal serrated portion and triangular distal end (arrow in
Fig. 3b
); 3) outer lobe of the maxillule with a very thick, claw-like bristle (arrow in
Fig. 3c
).
Distribution.
Setacheres portobarrensis
, like the other known members of the genus (
Johnsson
et al
. 2016
), occurs in the Tropical Southwestern Atlantic Province (TSA) (Spalding
et al.
2007), as observed for
S. abrolhensis
,
S. lunatus
,
S. aplysinus
, and
S. spinopaulus
(Johnsson & Neves 2012)
. Further studies may provide additional information about the range of the new species.