Cirolana Leach, 1818

Sidabalok, Conni M. & Bruce, Niel L., 2018, Review of the Cirolana ‘ pleonastica-group’ (Crustacea: Isopoda: Cirolanidae) with description of four new species from the Indo- Malaysian region, Raffles Bulletin of Zoology 66, pp. 177-207 : 178-179

Genus Cirolana Leach, 1818

Restricted synonymy. Bruce, 1986: 139.— Kensley & Schotte, 1989: 132.— Brusca et al., 1995: 17.— Schotte & Kensley, 2005: 1218.

Type species. Cirolana cranchi Leach, 1818 , by monotypy (see Bruce & Ellis, 1983).

Detailed diagnoses have been given by Bruce (1986) and Brusca et al. (1995). The group diagnosis offered below is framed against those diagnoses. The group is named for the first named of the included species.

Diagnosis of Cirolana ‘ pleonastica -group’. Body surfaces not polished, usually without chromatophores. Head without rostral point, usually anteriorly rounded, sometimes forming weak broadly rounded projection. Frontal lamina pentagonal, quadrate or anteriorly rounded; frontal margin projecting or flush, anteriorly not overlapped by rostrum. Dorsal surface of at least pereonites 6 and or 7, pleonites (usually 3–5) and pleotelson with transverse rows of nodules and tubercles ornamentation. Pleonite 1 largely concealed by pereonite 7, pleonites 3 and 4 weakly produced laterally and posteriorly, with pleonite 3 not extending posteriorly beyond pleonites 4 and 5; pleonite 4 posterolateral margin broadly rounded, extending posteriorly beyond pleonite 5. Pleotelson often with paired submedial longitudinal carinae or paired rows of submedial tubercles; lateral margins straight or weakly to moderately sinuate; posterior margin narrow, truncate or narrowly rounded, with 6–8 RS. Penial process opening flush (only Cirolana trulla , new species with low tubercles). Uropodal exopod lateral margin with widely-spaced and acute robust setae (usually 3 robust setae present; a slender base tapering from the flagellum).

Sexes dimorphic. Male uropodal exopod and endopod sometimes with dense mass of setae distally, with the uropodal exopod longer than in the female (e.g., Cirolana fasfes , new species, Fig. 9 ), sometimes a different shape to the uropodal rami; setal brush on antennal flagellum and more strongly dorsal developed ornamentation. Females show less ornamentation than males, lack a setal brush on antenna flagellum, with uropod and pleotelson shape and setation similar to immature individuals.

Remarks. Bruce (1986) defined the Cirolana ‘tuberculate group’ with the following characters: the presence of tubercles and or nodules on the pereonites, pleonites or pleotelson, the lack of setose fringe on pereopod 1 of the males, the extension of appendix masculina slightly beyond the endopod of pleopod 2 and the endopod of pleopod 1 not distally narrowed. At that time Bruce (1986) commented that while the Cirolana ‘ parva -group’ was consistent in the characters that it showed, this was less the case with the ‘tuberculategroup’ with some species that could not clearly be fitted into the group. There has been no further attempt to define this group of species. Equally, while the ‘southern group’ is defined principally by lacking nodular ornamentation (implicit in the key) and the uropodal exopod having widely spaced setae, the latter character is commonplace among coral-reef species in the ‘ pleonastica -group’ prompting us to question the validity of those species as a definable group.

The Cirolana ‘ pleonastica -group’ as defined here occurs primarily on coral-reefs of the Indo-Pacific region ( Bruce, 1986, 1994, current paper), and presents a narrower concept than that of Bruce (1986). We refer to this group of species as the ‘ pleonastica -group’, using the epithet of the first described species as the group does not include all species of Cirolana that have some form of nodular dorsal ornamentation.

There are several species with nodules and tubercles on the pereonites, pleonites and pleotelson yet lacking the defining characters of Cirolana ‘ pleonastica -group’ such as the widely spaced setae on uropod exopod. These include most of the ornate South African species, some estuarine species and also the so-called ‘southern group’ of Bruce (1986). We discuss those differences in turn.

The ‘southern-group’ shares several of the characters of the Cirolana ‘ pleonastica -group’— rounded anterior margin of the head, uropodal exopod with few widely-spaced robust setae, narrowly truncate pleotelson posterior margin and penial openings that open flush with the sternal surface. Dorsal nodules are weak or absent in this group, and all species have a noticeably distally narrow pleopod 1 endopod. Males have a setose fringe on the inferior margin of pereopod 1, a homoplasious occurrence also seen in some species of the Cirolana ‘ parva -group’. There are five species in this group: Cirolana furcata Bruce, 1981 ; C. halei Bruce, 1981 ; C. similis Bruce, 1981 ; C. triloba Bruce, 1981 ; and C. victoriae Bruce, 1981 . At present it is unclear what the relationship of this group to others within the genus.

Cirolana kiliani Müller, 1993 ; C. meseda Hobbins & Jones, 1993 ; C. comata Keable, 2001 ; C. dissimilis Keable, 2001 ; C. aldabrensis Schotte & Kensley, 2005 ; and C. bambang Sidabalok & Bruce, 2018 are superficially similar to species of the C. ‘ parva -group’, with bifid uropod apices and linguiform pleotelson; they differ in having prominent penial processes and lack a ventrally produced rostral point that overlaps the frontal lamina.

Several species from South Africa, Cirolana mclaughlinae Bruce & Brandt, 2006 and C. australis Keable, 2001 from the Southern Ocean (see ‘Materials and methods’) are dorsally ‘rugose’ with pitted cuticle and nodules. There are a number of characters that preclude these and similar species from being placed in the Cirolana ‘ pleonastica -group’, including prominent penial processes, the uropodal exopod lateral margin with continuous slender setae and robust setae, several species have obvious and dark chromatophores, and the pleotelson marginal plumose setae extend further anteriorly to the robust setae than in the ‘ pleonastica -group’. Several species have the anterior margin of the frontal lamina with a ventral ridge or projecting strongly. Unfortunately, most South African species (see Kensley, 1978) remain effectively not described by modern standards, so it is impossible at present to evaluate the relationships of those species. Cirolana mclaughlinae Bruce & Brandt, 2006 is typical of this group of species.

About half of all species in the genus do not readily fit into any notional ‘groups’. These include the type species for Cirolana , C. cranchi Leach, 1818 , and also C. harfordi ( Lockington, 1877) , C. pustulosa Hale, 1925 , and C. willeyi Stebbing, 1904 ; as previously mentioned the South African species and also species such as C. coronata Bruce & Jones, 1981 that show no evident affinity to other species. These species have continuous setae and robust setae on uropodal exopod lateral (vs widely spaced), lack articulated penial process, some dorsal ornamentation (very fine in C. cranchi and C. harfordi ) and the pleotelson plumose marginal setae extend well to the anterior of the robust setae. These species appear most similar to the South African species, different principally in lacking penial processes.

Figures

Fig. 9. Cirolana fasfes n. sp. A–C, E–F, holotype male (7.4 mm) (MZB Cru.Iso 090), Raja Ampat, Indonesia. D, G, H, paratype male (7.2 mm) (MZB Cru.Iso 091), Raja Ampat, Indonesia. I, paratype female (5.9 mm) (MZB Cru.Iso 091), Raja Ampat, Indonesia. A, dorsal view; B, lateral view; C, head; D, antenna peduncle; E, frons; F, pleon; G, antennule; H, uropod male; I, uropod female.