A new species of deepsea Tegastidae (Crustacea: Copepoda: Harpacticoida) from 9 ° 50´N on the East Pacific Rise, with remarks on its ecology *
Author
Gollner, Sabine
Author
Ivanenko, Viatcheslav N.
Author
Arbizu, Pedro Martinez
text
Zootaxa
2008
1866
323
326
journal article
49028
10.5281/zenodo.183742
a15db27b-703c-4e7d-83f6-b3f068e0cfa7
11755326
183742
Genus
Smacigastes
Ivanenko & Defaye
Type
species
Smacigastes barti
sp. nov.
Type
material
Holotype
dissected Ψ, 19 slides (nr.
SMF
31411)
Paratype
1: dissected ɗ, 13 slides (nr.
SMF
31412)
Paratype
2: Ψ (nr.
SMF
31413)
Paratype
3: ɗ (nr.
SMF
31414)
Paratype
4: Ψ (nr.
SMF
31415)
Paratype
5: ɗ (nr.
SMF
31416)
Paratype
6: Ψ (nr.
SMF
31417)
Paratype
7: ɗ (nr.
SMF
31418)
Paratype
8: dissected copepodite stage V, 3 slides (nr.
SMF
31419)
Paratype
9: Ψ (nr.
OLML
2007/199)
Paratype
10: ɗ (nr.
OLML
2007/200)
Paratype
11:Ψ (nr.
OLML
2007/201)
Paratype
12: ɗ (nr.
OLML
2007/202)
Paratype
13: copepodite stage V (nr.
OLML
2007/203)
Type
locality
East Pacific Rise (EPR);
9°50.447´N
,
104°17.493´W
;
2500 m
depth. The site Tica is located on the EPR between the
Clipperton
and Sequeiros transform faults. The site was colonized by the giant tubeworm
Riftia pachyptila
in 1997 (
Fornari et al. 2004
).
Type
material was collected from artificial substrates (PVC hoses) deployed in 2002, and recovered one year later (see Govenar & Fisher 2007).
Etymology
The species is named in honor of Breea Govenar who designed the artificial devices from which specimens were collected (
BART
: Breea´s Artificial
Riftia Tubes
).
Female
Body (
Fig.1
a, 1b, 2a) laterally compressed, weakly chitinized, with short sensilla and few pores. Total length of female
holotype
(rostrum to posterior margin of telson) 420 µm, greatest width 180 µm. Rostrum rounded and prominent (
Fig. 1
a). Prosome 4segmented (cephalothorax and 3 somites bearing legs 2 to 4) (Fig. 2a). Urosome (Fig. 2b) 5segmented: first urosomite with leg 5, genitaldouble somite with ventral depression and one gonoporus covered by flap of the minute leg 6 (
Fig. 1
c, 5b, 5c), and 2 postgenital somites plus telson with furca. Furca 3 times as long as wide, with 7 setae of different length (Fig. 2c).
Antennule (Fig. 2d) 7segmented; formula of setation: 1, 10, 9, 3+aesthetasc, 6, 4, 6+aesthetasc.
Antenna (Fig. 2e) with small coxa and elongate basis with 1 seta and a field of cuticular spinules. Exopod 2segmented, proximal segment with 1 inner setae, distal segment with 3 apical setae; endopod 2segmented, proximal segment with 1 median seta, distal segment with 4 inner setae, 6 terminal setae and a hyaline frill subdistally on outer margin.
Labrum (Fig. 2a) projecting over shield of cephalothorax in lateral view.
Mandible (
Fig. 3
a) with gnathobase (not shown); palp 2segmented, with 2 distal setae on basis and 1segmented endopod bearing 1 outer and 3 terminal setae.
Maxillule (
Fig. 3
b, c) with praecoxal arthrite bearing 8 spines; coxal endite with 1 seta; exopod with 2 setae; basis elongate with 1 median and 4 terminal setae.
Maxilla (
Fig. 3
d) syncoxa with two endites, proximal endite with 1, distal endite with 3 spines. Allobasis with 3 lateral setae, two subdistal and one apical spine.
Maxilliped (
Fig. 3
e, f) 3segmented, subchelate; syncoxa elongated with 1 distal seta; basis with 2 rows of spinules; endopod 1segmented, produced into a strong claw, with 2 proximal setae and an inner row of short spinules.
Swimming legs 1–4 biramous; armature formula as in Table 1.
TABLE 1.
|
Spine |
and |
setal formula of |
legs |
1–4 of
Smacigastes
|
barti
sp. nov.
|
Legs |
Coxa |
Basis |
Exopod |
Endopod |
Leg 1 |
00 |
10 |
2, I, 1 |
1, II, II1 |
Leg 2 |
00 |
10 |
II2; II, I, 3 |
01; 02; I, II, 2 |
Leg 3 |
00 |
10 |
II2; II, I, 4 |
01: 02; 1, II, 3 |
Leg 4 |
00 |
10 |
I0; I1; II, I1, 1I1 |
01; 02; I, II, 2 |
FIGURE 1.
Smacigastes barti
sp. nov.
SEM photos: Ψ paratype: A, habitus, ventral (rostrum indicated by arrow); B, habitus, lateral; C, genitaldouble somite with leg 6 (see arrow); ♂ paratype: D, habitus, lateral; E, spermatophore reservoir with opened gonopore and leg 6 (see arrow). Scale bars A, B, D 100 µm; C, E 20 µm.
FIGURE 2.
Smacigastes barti
sp. nov.
Ψ
holotype
LM drawings: A, habitus, lateral (labrum indicated by arrow); B, urosome, ventral; C, furca, ventral; D, antennule (a seta on 2nd segment broke and is indicated by a circle); E, antenna (frill indicated by arrow). Scale bars A 100 µm; B–E 50 µm.
FIGURE 3.
Smacigastes barti
sp. nov.
Ψ holotype LM drawings: A, mandible; B, maxillule; C, maxillule (different view, from ♂ paratype 1); D, maxilla; E, maxilliped, posterior; F, maxilliped, anterior. Scale bars A–D 10 µm; E, F 50 µm.
FIGURE 4.
Smacigastes barti
sp. nov.
Ψ holotype LM drawings: A, leg 1; B, leg 2; C, leg 3; D, leg 4. Scale bars A–D 50 µm.
FIGURE 5.
Smacigastes barti
sp. nov.
Ψ holotype: A, distal endopod segment of leg 4; B, leg 5; C, leg 6 (Ψ paratype 2); ♂ paratype 1 LM drawings: D, leg 5; E, leg 6 (see arrow; ♂ paratype 3). Scale bars A, C–E 50 µm; B 100 µm.
FIGURE 6.
Smacigastes barti
sp. nov
♂ paratype 1 LM drawing: A, habitus, lateral; B, antennule; paratype 8 copepodite stage V LM drawings: C, leg 2; D, leg 3. Scale bars A–D 50 µm.
Leg 1 (
Fig. 4
a) with 1segmented rami.
Leg 2 and leg 3 (
Fig. 4
b, 4c) with 3segmented endopods and 2segmented exopods; proximal segments of exopods elongated, derived by fusion of former proximal and middle segments.
Leg 4 (
Fig. 4
d) with 3segmented rami. Distal exopod segment with an inner seta slightly modified into a spine (
Fig. 5
a).
Leg 5 (
Fig. 5
b) with baseoendopod and exopod; baseoendopod with 1 basal outer seta, 3 inner setae, 1 terminal spine, and 1 small terminal outer seta; exopod with 3 outer elements (proximal setalike; middle and distal ones spinelike), and 2 terminal spines.
Leg 6 a small flap with 1 minute seta (
Fig. 5
c).
Single egg sac with three eggs, located ventrally between fifth legs (
Fig. 1
b, 1c, 2a).
Male differs from female in the following:
Length of
paratype
1 (
Fig. 1
d, 6a) 325 µm; greatest width 150 µm. Genitaldouble somite (
Fig. 1
e, 5e) produced ventrally into a large, elongated prominence bearing a distally asymmetrical genital flap representing leg 6.
Antennule (
Fig. 6
b) 10segmented; setation formula as follows: 1, 10, 6+aesthetasc, 1, 7+aesthetasc, 1, 2, 1, 4, 7+aesthetasc.
Leg 5 (
Fig. 5
d) 2segmented; basis with 1 outer seta, exopod with 1 outer proximal seta, 1 outer subdistal spine, and 2 terminal spines.
Leg 6 (
Fig. 1
e, 5e) a membranous genital flap on the left side.
One spermatophore stored inside the genitaldouble somite (
Fig. 5
e).
Copepodite stage V
Leg 2 (
Fig. 6
c) and Leg 3 (
Fig. 6
d) consist of 3segmented exopods (in contrast to adult) and 2segmented endopods (shortly before division into the adult 3segmented endopod).