Ophelina described

Parapar, Julio, Al-Kandari, Manal, Barroso, María & Moreira, Juan, 2023, The genus Ophelina Örsted, 1843 (Annelida: Opheliidae) in the coast of Kuwait (northern Indian Ocean), with the description of a new species, European Journal of Taxonomy 870 (1), pp. 1-29 : 21-24

Key to species of Ophelina described /reported in the Indian Ocean

The key comprises species of Ophelina originally described from the Indo-Pacific, Southern Asia, Indo-Malay Archipelago, and Australia, plus those two European species reported from the Arabian Gulf. The main characters used to discriminate among species are the anal tube features, including the unpaired anal cirrus, paired marginal papillae and the pair of basal papillae.

We follow Rullier (1965), Kongsrud et al. (2011), Parapar & Moreira (2015), Moreira & Parapar (2017), Magalhães et al. (2019), and Parapar et al. (2021a, 2021b) when using the term “anal tube” instead of many others used before (see Remarks to the diagnosis of genus). Anyhow, we must state that this structure is a pygidial construction instead of being only restricted to the anal part itself and that the shape of the anal tube is not indeed “tubular” in all species. Besides, the anal tube shape is also a relevant diagnostic character, but various terms in the literature refer to its very shape. Therefore, the two main appearances are used in the key: 1) tube longer than wide (“groove-shaped”) and 2) tube as long as wide (“spoon/hood-shaped”).

Other body characters of high taxonomic relevance in the genus Ophelina were not used in this key, such as the parapodial shape. Because many available descriptions (especially those from the early 20 th century) still need to be completed; this would require a revision of the available type material of a number of species. Such revision might eventually result, in turn, in the erection of new species. Redescriptions and taxonomic comments are available across the literature for several species, but we intended to follow original descriptions and illustrations as much as possible unless indicated otherwise.

The key also includes the European O. acuminata Örsted, 1843 and O. longicaudata ( Caullery, 1944) because they have been previously reported in the Indian Ocean. However, these records might actually correspond to other described and/or new species. On the other hand, three species were not included in the key:

1) Ophelina dubia ( Caullery, 1944) : the original description does not describe the anal tube, apparently lost (“Le tube anal manque sur l’échantillon”, Caullery 1944: 45).

2) Ophelina ehlersi ( Horst, 1919) : the original description confirms the presence of paired basal papillae but states that “The anal tube is short (?broken off)” ( Horst 1919: 23), and therefore the presence of paired marginal papillae and unpaired anal cirrus is not mentioned/confirmed.

3) Ophelina kükenthali ( Horst, 1919) : the original description reports the anal tube as “gutter shaped”, and the presence of the unpaired anal cirrus and 8–9 “cirri” on the posterior margin (supposedly the paired marginal papillae), but no illustration is provided and sizes/proportions among each other are not mentioned. Later, Neave & Glasby (2013) wrongly state that this species lacks the unpaired anal cirrus, and bears instead the pair of basal papillae.

The type locality of each species is indicated between brackets.

1. Anal tube (AT) with all three types of anal cirri/papillae ............................................................... 12 – AT lacking at least one type of anal cirri/papillae ............................................................................ 2

2. AT without paired marginal papillae ................................................................................................. 3 – AT with paired marginal papillae ...................................................................................................... 7

3. AT as long as wide (bell, spoon or hood-shaped) ............................................................................. 4 – AT longer than wide (tube or groove-shaped) .................................................................................. 5

4. Prechaetal lobes well developed; anterior-most lobes almost as long as branchiae; branchiae longer than chaetae; anal tube opened ventrally, heart-shaped and pointed at dorsal end ............................. ..................................................................................... O. cordiformis ( Caullery, 1944) 1 [ Indonesia]

– Prechaetal lobes poorly developed; branchiae small, shorter than chaetae; anal tube very short with ventral prolongation ............................................. O. brevibranchiata ( Caullery, 1944) 2 [ Indonesia]

5. Unpaired ventral cirrus present ......................................................................................................... 6 – Unpaired ventral cirrus absent .......................... O. langii ( Kükenthal, 1887) [ Philippines; Fig. 12H ] 6. AT opened dorsally at distal end .................................................. O. arabica sp. nov. [Arabian Gulf] – AT fused dorsally ................................................. O. cylindricaudata ( Hansen, 1879) [NE Atlantic]

7. AT unpaired anal cirrus absent .......................................................................................................... 8 – AT unpaired anal cirrus present ...................................................................................................... 10

8. AT pair of basal papillae present ....................................... O. buitendijki ( Horst, 1919) 3 [ Indonesia] – AT pair of basal papillae absent ........................................................................................................ 9

9. Midbody branchiae length about 0.5 body width ........... O. pygocirrata ( Ehlers, 1920) 4 [ Indonesia] – Midbody branchiae length about 2.0 body width ............................................................................... .................................................... O. longicirrata Hartmann-Schröder & Parker , 19955 [S Australia]

10. AT ventral margin fused. Paired marginal papillae about 0.05 times AT length; ............................... ..................................................................................... O. longicaudata ( Caullery, 1944) [ Indonesia] – AT ventral margin not fused. Paired marginal papillae>0.05 times AT length ..............................11

11. Paired marginal papillae as long as AT .............................. O. bimensis ( Caullery, 1944) [ Indonesia] – Paired marginal papillae about 0.2 times AT length ....... O. profunda ( Caullery, 1944) 6 [ Indonesia]

12. AT as long as wide .......................................................................................................................... 13 – AT longer than wide ........................................................................................................................ 15

13. Unpaired ventral cirrus provided with paired papillae along both sides ............................................ ............................................................................................. O. remigera ( Ehlers, 1918) 7 [ Indonesia] – Unpaired ventral cirrus not provided with papillae ........................................................................ 14

14. Paired marginal papillae similar in shape and length (about 0.05 times maximal AT length) ........... .............................................................................. O. tessellata Neave & Glasby, 2013 [N Australia]

– Paired marginal papillae of different shape and length (about 0.2 times maximal AT length) ........... ............................................................................................. O. fauveli ( Caullery, 1944) 8 [ Indonesia]

15. Paired marginal papillae of different length 9 ................................................................................. 16 – Paired marginal papillae of same length 9, 10 ................................................................................... 17

16. Posterior paired marginal papillae longer than anterior ones ............................................................. ........................................................................... O. cyprophilia Neave & Glasby, 2013 [N Australia]

– Anterior paired marginal papillae longer than posterior ones ............................................................ ....................................................................... O. grandis ( Pillai, 1961) 10, 11 [ Sri Lanka; Fig. 12A–B ]

17. Paired marginal papillae length <0.1 times maximal AT width ..................................................... 18 – Paired marginal papillae length> 0.1 times maximal AT width ..................................................... 19

18. Pair of basal papillae <0.1 times unpaired ventral cirrus length ........................................................ ................................................................................ O. kampeni ( Horst, 1919) [ Indonesia; Fig. 12G ]

– Pair of basal papillae about 0.5 times unpaired ventral cirrus length ................................................. ............................................................................ O. gigantea ( Rullier, 1965) [E Australia; Fig. 12C ]

19. Unpaired ventral cirrus longer than maximal AT length ... O. acuminata Örsted, 1843 [NE Atlantic] – Unpaired ventral cirrus not longer than maximal AT length .............................................................. ........................................................................... O. sibogae ( Caullery, 1944) 11 [ Indonesia; Fig. 12F ]

(1) Eibye-Jacobsen (2002) describes specimens identified as Ophelina cf. cordiformis from the Andaman Sea and discusses similarities/differences with the only type specimen of O. cordiformis , which is damaged according to the original description by Caullery (1944).

(2) “Je n’y ai pas aperçu de papilles marginales, ni de branchie anale” ( Caullery 1944: 46). The original description and drawings by Caullery (1944) for O. brevibranchiata are much simpler than those provided for other species in the same work; therefore, this species is not well characterised morphologically yet.

(3) Following the original description by Horst (1919) and that by Neave & Glasby (2013), no illustration is available.

(4) Following the original description by Ehlers (1920) and that by Neave & Glasby (2013), no illustration is available.

(5) Following the original description by Hartmann-Schröder & Parker (1995) and that by Neave & Glasby (2013).

(6) Caullery (1944) states in the original description that the unpaired anal cirrus is not present (“Je n’ai pas vu de branchie anale”; Caullery 1944: 47); however, Caullery (1944: fig. 38c) illustrates a long cirrus coming out from the interior of the anal tube that might likely correspond to a true unpaired anal cirrus.

(7) Ehlers (1918) mentions in the anal tube a “a brownish, short ovate body” (in German in original source: “ein bräunlicher, kurz eiförmiger Körper”; Ehlers 1918: figs 2–3 in table xvii). This structure might correspond to the only papilla remaining of the pair of basal papillae as present in other species. Furthermore, Neave & Glasby (2013) describe a “second protrusion” that we recognise as the unpaired anal cirrus.

(8) The concept provided by Neave & Glasby (2013) for this species is different to that of the original description (see remarks above).

(9) This feature might have been overlooked in the original descriptions of some species.

(10) This feature is also present in European specimens of O. acuminata but not in specimens from South Africa illustrated by Day (1967); the latter may, therefore, represent a different species (see Remarks for O. arabica sp. nov.).

(11) The descriptions by Eibye-Jacobsen (2002) for specimens identified as belonging to O. grandis and O. sibogae differ from the original descriptions regarding features of the anal tube; therefore, these specimens might represent undescribed species (see also Remarks for O. arabica sp. nov.).

Figures

Fig. 12. Line drawings of several Indo-Pacific species of Ophelina (all redrawn from original sources). A–B, D–E. Ophelina grandis (Pillai, 1961). C. Ophelina gigantea (Rullier, 1965). F. Ophelina sibogae (Caullery, 1944). G. Ophelina kampeni (Horst, 1919). H. Ophelina langii (Kükenthal, 1887). A. Anterior body, lateral view. B. Posterior body end, ventral view. C. Last body chaetigers and anal tube, ventral view.D. Buccal tentacles. E. Anal tube, lateral view. F. Last body chaetigers and anal tube, ventral view. G–H. Last body chaetigers and anal tube, lateral view. Sources for drawings: A–B = Pillai (1961); C = Rullier (1965); D = Gallardo (1968); E = Eibye-Jacobsen (2002); F = Caullery (1944); G = Horst (1919); H = Kükenthal (1887). Abbreviations: aclc = anterior chaetigers long chaetae; br_a = branchiae - anterior; br_p = branchiae - posterior; pbp = pair of basal papillae; pmp_p = paired marginal papillae - posterior; pmp_v = paired marginal papillae - ventral; uac = unpaired anal cirrus.