New genera and species of the marine isopod family Serolidae (Crustacea, Sphaeromatidea) from the southwestern Pacific
Author
Bruce, Niel
Museum of Tropical Queensland, Townsville, Queensland, Australia
text
ZooKeys
2009
2009-08-26
18
18
17
76
journal article
22617
10.3897/zookeys.18.96
1b25d91d-c28e-48fa-aee7-f7a9d26c61cd
1313–2970
576495
87B9757A-986D-4CCC-8276-146A617FC905
Caecoserolis
Wägele, 1994
Caecoserolis
Wägele, 1994: 10
(not
Caecoserolis
of
Poore and Brandt 1997: 161
; =
Myopiarolis
gen. n.
)
Type
species.
Serolis brinki
Kensley, 1978
; original designation (
Wägele 1994
).
Description
.
Head
lateral lobe mesial margin with single concavity; anterolateral lobes forming of continuous margin with pereonite 1; anterior submarginal ‘ridge’ absent; posterior margin without ornamentation.
Eyes
absent.
Pereonites
all entire, articulating; pereonite 1 anterior margin not strongly bent dorsally, dorsally without tubercles.
Coxae
of pereonites 2–4 articulated, with dorsal sutures; 2–4 and pereonite 6 entirely lacking coxal keys; distal margin truncate; coxae 6 wide, laterally or distally broad, extending proximal to insertion of uropod peduncle.
Ventral coxal plates
2–4 meeting midline; simple, smooth; plates 6 and 7 entirely separate.
Pleonites
distally narrow or acute, laterally overlapped by coxae 6, extending posteriorly along pleotelson.
Sternites
5–7 visible, fused.
Sternal
plates of pleonites 1–3 3-cornered, with acute median point, without median ridge.
Pleotelson
dorsal surface not vaulted, with weak median longitudinal carina, without paired sublateral carinae; pleotelson posterior margin evenly rounded, without distinct exit channel.
Antennule
flagellum 1.2–2.0 as long as peduncle articles 3 and 4, extending to pereonite 2.
Antenna
peduncle articles 4 and 5 broad, article 5 less than 5 times as long as greatest width; flagellum three-quarters as long as peduncle article 5.
Epistome
evenly rounded.
Mandible
incisor with two posterior cusps; left mandible lacinia mobilis three-quarters as wide as incisor or larger, right lacinia mobilis distally multicuspid; mandibular spine distally serrate.
Maxilliped
palp with 3 articles; article 3 cordiform, longer than wide.
Pereopod 1
carpus RS–state not known (pilose
vs
serrate); propodal palm setae all RS, alternating straight and flattened, wide RS finely pilose, narrow RS distally bifid, with simple flagellum.
Pereopod
2 propodus inferior margin without heel; palm straight; unguis simple, blunt.
Penial
openings narrowly separated.
Pleopods
1–3 peduncles subquadrate. slightly narrower distally, pleopods 1–3 peduncles with coupling setae.
Pleopod
2 endopod lamellar part slightly shorter than ramus.
Uropods
Biramous, inserted on pleotelson mid-laterally, positioned laterally, not forming part of continuous body outline; less than one-third as long as pleotelson, endopod distally rounded.
Remarks
.
Caecoserolis
belongs with the group of genera characterised by having a distal stem on pleopod 2 endopod, approximating to the ‘Group B’ of
Wägele (1994)
. The genus can be identified by the flat (or weakly domed) pleotelson that lacks lateral carinae, antenna with broad peduncular articles 4 and 5, pleopod peduncles that are sub-quadrate (slightly narrower distally than proximally) and by the short uropods inserted mid-laterally on the pleotelson; another less precise character is that
Caecoserolis
has a flatter body than related genera.
All but the
type
species of
Caecoserolis
have been transferred to the
Myopiarolis
gen. n.
Th e characters that most readily separate these two genera (in parentheses for
Myopiarolis
) include antenna peduncle articles 4 and 5 broad with article 5 less than 5 times as long as greatest width (slender, elongate, 4.6–6.3 and 8.6–10.3 as long as wide respectively), pleopods 1–3 peduncles quadrate or subquadrate (triangular), pereonite 1 anterior margin anterior margin weakly indented (distinctly indented), pereonites all with visible entire sutures (pereonites 5–7 sutures medially fused), simple and flat pleotelson that lacks sub-lateral carina (pleotelson vaulted, with sub-lateral carinae), coxae 6 not extending posteriorly to pleonites (extending posteriorly to pleonites) and penial openings narrowly separated (fused in all species of
Myopiarolis
).
Distribution
.
The genus is monotypic, with one western Indian Ocean species, off the Natal coast of
South Africa
.