Serpula jukesii Baird, 1865

Ben-Eliahu, M. Nechama & Ten Hove, Harry A., 2011, Serpulidae (Annelida: Polychaeta) from the Suez Canal- From a Lessepsian Migration Perspective (a Monograph) 2848, Zootaxa 2848 (1), pp. 1-147 : 83-87

Serpula jukesii Baird, 1865

Table 4

Type locality. East coast of Australia. Most probably not present in the Suez Canal proper, see Remarks, below .

Preliminary remarks. Since the presence of Serpula jukesii Baird (1865: 20 , pl. 2 fig. 6) in the Suez Canal has not (yet?) been authoritatively demonstrated, we have refrained from a full treatment of the taxon here. For comparison, however, we reviewed the literature of larger Serpula taxa from Indo-West-Pacific origin and studied dozens of samples, as S. jukesii (including its holotype BM (NH) ZB 1982: 84), vermicularis sensu auct., vermicularis granulosa , magna , vasifera , originating from Kuwait to Japan, from India to Australia. Some of this has been summarized in Table 4. Below we also comment upon relevant records from the nearby Gulfs of Suez and Aqaba.

Material examined. Gulf of Suez: Cambridge Expedition, stn R5, 5.XI.1924, det. F.A. Potts (1928: 700) Serpula vermicularis , fragments of a specimen discussed in detail below.— 33° 23’ E., 28°14’ N, 22 m, muddy sand, St. 17 bis, R.Ph. Dollfus Exp., 25.XII.1928, det. P. Fauvel (1933a: 76) S. vermicularis , redet. S. jukesii herein, CUZM, 1 spec. Operculum of specimen symmetrical with blunt teeth, its “waist” at mid-point; expanded basal bulb; constriction, deep funnel, 54 marginal radii (teeth); 40 radioles per lobe; tube white, pink inside, tubes without ridges; collar trilobed; apron; collar chaetae with 2 teeth; thoracic uncini F+4; anterior abdominal uncini F+5 and F+6.

Red Sea, legit G. von Frauenfeld, det. Grube (1868: 640) Serpula gervaisii , redet. H.A. ten Hove 1982 S. jukesii ( Table 4), Muzeum Przyrodnicze Wroclaw, 1 spec. Operculum showing tubercles on inner radii as opposed to type of S. jukesii .

(*) Revised numbers of opercular radii and number of radioles per branchial lobe by H.A. ten Hove following his observation of specimen.— 1) The number of opercular radii in Atlantic-Mediterranean Serpula vermicularis counted from different illustrations.— 2) It cannot be excluded that Mediterranean records earlier than 1991 included measurements of S. cavernicola , with 45–80 radii ( Fassari & Mòllica 1991).— 3) ten Hove & Jansen-Jacobs (1984: 150).— 4) Marenzeller (1885: 216) compared Serpula princeps Grube, 1877 described from N. Japan with his Serpula granulosa . However, Grube (1877) as referred to by Marenzeller [Naturh. Ber. d. Schles. Ges. f. vaterl. Cultur, 1877: 62] cannot be traced in the Dutch libraries, neither in the available bibliographies, nor is the name used again by Grube (1878 a: 104–105), where the same diagnosis as cited by Marenzeller (1885: 216) has been attributed to Serpula ? jukesii by Grube. Serpula princeps should be regarded to be a nomen nudum.— 5) Correction of observations of Straughan (1967a) in ten Hove & Jansen-Jacobs (1984), taxon synonymised with S. jukesii .— 6) Not given in Marenzeller, 1885.

Remarks. The taxonomy of the genus Serpula is exceedingly problematic. Without comparison of specimens to be identified with type specimens, or at least with topotypical material, identification is difficult under the best of circumstances. This is exacerbated when a specimen collected from within a transoceanic canal is unavailable for direct examination. The only record under the name Serpula jukesii was listed in a table (Abd- Elnaby 2009: 10), without any additional details. Regretfully, it was not possible to forward the material to Amsterdam for direct examination, however, the author generously responded to ten Hove’s request to count the number of opercular radii. On the basis of its having too few opercular radii (19 radii after damage, F.A. Abd-Elnaby, pers. comm. to H.A. ten Hove), we excluded the identification as Serpula jukesii for this Suez Canal specimen. In contrast, the taxon is excluded from an identification as Serpula hartmanae due to its having too great a number of radii (see Table 4), bayonet chaetae with 2 teeth, and by lacking an asymmetric boss on the peduncle, proximal to the constriction separating the peduncle from the operculum (F.A. Abd-Elnaby, pers. comm. to H.A. ten Hove). Given the present constraints, the most plausible conclusion is that the specimen is a juvenile Hydroides with a primary operculum (for a discussion of opercular ontogeny in Hydroides , see ten Hove & Ben-Eliahu 2005). As it lacks the characteristic collar chaetae of Hydroides elegans , we are provisionally identifying it as Hydroides sp. (not enumerated among the verified taxa of the canal, and listing it among the non-determined species below).

A nominal Serpula vermicularis sensu auct. had been collected in the Gulf of Suez and was included in Potts’ 1928 article on the Cambridge Expedition Sedentaria although not having been collected from within the Suez Canal proper. Potts (1928) referred to Pixell’s (1913) report of S. vermicularis in the Red Sea, which included citations from Antarctica, Patagonia and the Mediterranean Sea, “clearly a very unlikely distribution” (ten Hove & Jansen-Jacobs 1984). Potts’ (1928) Serpula was presumably of Indo-West-Pacific or / and Red Sea affinity, whereas the type locality of Serpula vermicularis is Sussex, England ( Heppell 1963: 445). By comparison with the distributions of other boreal-temperate taxa such as Pomatoceros triqueter , it may be safely assumed that Serpula vermicularis also occurs throughout the Atlantic-Mediterranean region. However, even this Atlantic-Mediterranean taxon might not be a single species. Ben-Eliahu & ten Hove (1992) and Ben-Eliahu & Fiege (1996) mentioned differences in tube structure and colour, which may have taxonomic importance. Preliminary work done by us (in 1990–unpublished) indicates that there may be statistical differences in number of opercular radii, length of interradial grooves between opercula of the “echinate” form and Serpula vermicularis “ s. str. ”. Earlier Mediterranean records too may have included material of S. cavernicola . The cosmopolitan status of Serpula vermicularis has been questioned by ten Hove & Jansen-Jacobs (1984); as a consequence Kupriyanova & Rzhavsky (1993) and Kupriyanova (1999) separated 2 valid North Pacific taxa, S. columbiana Johnson, 1901 and S. uschakovi Kupriyanova, 1999 , from the previously “cosmopolitan” S. vermicularis .

Potts (1928: 700) nominal Serpula vermicularis reported an operculum with 70 opercular radii (“radiating ridges”), radially symmetrical (“insertion not as in S. lobiancoi ”), borne on a lobe with 22 branchial radioles. Potts gave no details on body structure or chaetae. Regretfully, the vial with Potts’ nominal S. vermicularis specimen, comprised only a tube and a posterior fragment when reviewed in 1986 at the CUZM by M.N. Ben- Eliahu; the branchial crown and anterior were already missing. However, when rechecked in IX.2002, only the tube was present, along with some abdominal epidermal tissue adhering to it ( Fig. 11 ).

As Fig. 11A–C shows, Potts’ description of the tube was both Painstaking and accurate: A massive tube, “coiled in a plane spiral” and “the tube is not free anteriorly over a great part of its length”, as Fauvel states is the case in Serpula vermicularis ( Fauvel 1927: 352) . The number of longitudinal ridges on the tube was difficult to make out” ( Potts 1928). The tube resembles an enormous Spirorbis , and has a rather flattened upper surface with two blunt longitudinal ridges. Although the mouth of the tube appears rounded in cross-section, there are pronounced transversal ridges (i.e., former peristomes), and it has a thick granular overlay ( Fig. 11C , see discussion below).

Other Indo-West-Pacific records of nominal Serpula vermicularis should be checked individually against the voucher specimens. For example, Serpula jukesii sensu Grube (1878) , from Japan should be referred to S. uschakovi (fide Kupriyanova 1999). Potts’ (1928) questionable Gulf of Suez specimen would fit into the biogeographical pattern of Serpula jukesii .

Dealing with possible synonymies of nominal Serpula taxa, ten Hove & Jansen-Jacobs (1984) wrote: Of the small number of useful taxonomic characters in Serpula , the “most important is the number of opercular radii”. According to these authors, Serpula vermicularis from Australian waters generally should be named S. jukesii (including S. magna ).

Serpula vermicularis granulosa sensu Mohammad (1971 , Kuwait, 2 specs) and S. gervaisii not Quatrefages, 1866, sensu Grube (1868), Red Sea, 1 spec., were considered to be possible synonyms of S. jukesii . They are characterised by similar form in tubes, thoracic membranes not forming an apron on the ventrum, 3- toothed collar chaetae, and a very large number of opercular radii (i.e., marginal teeth) with and sometimes without distinct surface tubercles. Data on the collar chaetae and the thoracic membranes of Potts’ Serpula would have provided important support for identifying the specimen. Nonetheless, the described operculum falls within the Serpula jukesii / S. granulosa complex (sensu ten Hove & Jansen-Jacobs 1984: 143–152). In a later paper, ten Hove (1994: 111) suggested that both taxa might be valid; ten Hove & Kupriyanova (2009: 94) treated both as separate taxa. The number of opercular radii of these nominal taxa ranges from 40–100 ( Table 4). For perspective, Table 4 also gives the range of number of marginal radii for Atlantic-Mediterranean Serpula vermicularis s. str., ranging from 25–61, with an illustration of local differences in this taxon in numbers of radii, as opercula from a purely Norwegian population were of larger size than those compiled from various areas including the Mediterranean. Size differences for warmer and colder-water populations of invertebrate species are a phenomenon described by Gunter (1957: 174) and Mayr (1966: 327) and might be found in S. vermicularis as well. Alternatively, the Atlantic-Mediterranean S. vermicularis sensu auct. might prove to be a complex of two (cryptic) species.

Attributing the operculum described by Potts (1928) to the Serpula jukesii / granulosa- complex creates a dilemma, as the tube, with its regular flat tight spiral coiling, is not characteristic for Serpula . It appears certain that the tube and operculum are “mismatched”. Flat coiled spiralling is, however, known for an occasional Hydroides (H. Zibrowius, pers. comm. and our own unpublished observations and illustrated by Kupriyanova & Jirkov 1997), for Spiraserpula ( Pillai & ten Hove, 1994) , as well as for the bathyal Nogrobs (cf. ten Hove & Kupriyanova 2009: 68). A Hydroides identification for the tube is not contraindicated by the abdominal chaetae from the epidermis removed from the tube lumen ( Fig. 11D–F ). The most plausible solution to this dilemma is that the opercular crown and the tube were fragments of two taxa collected together and placed in the same vial (H. Zibrowius, pers. comm.), so that Potts’ record of this sample should be revised to Serpula ? jukesii and to Hydroides sp. Moreover, once the possibility of Hydroides sp. is accepted, we suggest the tube could belong to H. heterocerus , the largest of the Hydroides species known from this area, and one with several records from the Gulf of Suez, indeed from the same general location, e.g., Suez quay ( Pixell 1913: 75), Gulf of Suez ( Fauvel 1933a, b) [see above section dealing with Hydroides heterocerus ]). Potts (1928) did not indicate whether he had examined a “loose” branchial crown—one separated from a worm body floating in the sample material—or seen the body belonging to the operculum.

Serpula ? jukesii as understood by ten Hove & Jansen-Jacobs (1984: 149) shows considerable intraspecific variability in the collar chaetae: One heavy tooth and two accessory ones or three heavy teeth and two accessory ones, or four nearly equal teeth. However, Serpula nudiradiata Pillai 2009 (pp. 136–139) may have been included in S. jukesii by ten Hove & Jansen-Jacobs, possibly throwing a different light upon this variation, their material should be restudied. It should be noted that Pillai apparently did not see the holotype of Serpula jukesii in the BM(NH), at least it was not mentioned by him, and he might have observed that the holotype of S. jukesii does not show tubercles, as opposed to Pillai’s material of this nominal taxon (and that of S. gervaisii sensu Grube (1868)) which both do show tubercles. A further difference between the holotype and Pillai’s specimens is the presence of an apron, as the ample thoracic membranes are not joined to form an apron in the holotype of S. jukesii . In fact, this was one of the characters upon which ten Hove & Jansen-Jacobs (1984) determined synonymy of their S. jukesii and of S. magna (by comparison of types); however, this characterstate easily may be overlooked if not specifically studied and in some specimens it may be damaged (e.g., in S. gervaisii sensu Grube (1868)) . In conclusion, Serpula jukesii too should be revised. Other Indo-West- Pacific Serpula taxa listed in ten Hove (1994) or described subsequently have fewer radii or opercula of different shapes than in the S. jukesii / granulosa- complex (the following list mentions only opercula for comparison with the Potts (1928) description, without taking into consideration tube, collar chaetae and other Serpula pacifica ( Uchida, 1978) , a juvenile specimen, lacks an operculum (and was regarded as of uncertain identity by Pillai & ten Hove (1994: 103); Serpula japonica Imajima, 1979 , 21–24 radii, operculum zygomorphic; Serpula rubens has a bell-shaped operculum with or without a waist, with greater or lesser flare, with only 15– 18 radii (types restudied by us). Two taxa with opercula with very long external grooves; with hardly any distal flair; elongate, with rather straight sides (basal bulb not expanded, waist not well-defined: Serpula watsoni Willey, 1905 , ampulla deeply elongated; 33–55 radii, and Serpula sp. of Ishaq & Mustaquim (1996) 16–33 radii, ampulla shorter, profile rather squat; 9–31 radioles. Two taxa with opercula with very long external grooves, but distally flared, tapering to the constriction, basal bulb not expanded: Serpula vittata 18–23 radii and S. vasifera , 31 radii, respectively (according to their written descriptions, the illustrations are contradictory; other material identified by ten Hove had 25–34 radii). Three opercula with short external grooves, distally flared, tapering to the constriction, basal bulb not expanded: Serpula tetratropia Imajima & ten Hove, 1984 with 18–20 radii, raised central disc, somewhat pointed radii; S. zelandica Baird, 1865 , 13–21 radii (incompletely described) and S. longituba ( Imajima, 1979) , 31 radii, short external grooves, with a markedly tapered elongated ampulla. Four taxa with distally flared, bell-shaped opercula with rather short external grooves, and with a well-defined waist, basal bulb more or less expanded: Serpula willeyi Pillai, 1971 , 10 radii; S. hartmanae , 16–25 radii, with an asymmetric boss proximal to the constriction; S. oshimae 19–26 radii, lacking the boss, differs from S. hartmanae in collar chaetae. Similar, but larger, greatly flaring distally, Serpula indica 48–56 radii. Two taxa with hexagonal tusk-like tubes, Serpula crenata ( Ehlers, 1908) and S. sinica Wu, Sun & Chen, 1979 with 17–22 radii and 23 radii, respectively. Three gregarious Indo-West Pacific and Mediterranean taxa were transferred to the genus Spiraserpula because they have internal tube structures (ITS) by Pillai & ten Hove, (1994): Spiraserpula minuta ( Straughan, 1967b: 216, fig. 6 h–m) with only filiform pseudopercula ( Australia); Spiraserpula lineatuba Straughan, 1967b: 216 , fig. 6 h–m) ( Australia, Queensland and New South Wales), operculum slightly zygomorphic with 22–25 radii; outer grooves ca. midway and Spiraserpula massiliensis ( Zibrowius, 1968: 102–105, pl.1 figs 24–37, pl. 14 fig.), operculum with elongate funnel and rather flat distal cup with 10–23 radii and short outer grooves. The nominal Indo-West- Pacific Serpula philippensis McIntosh, 1885 , from abyssal depths, is poorly described (questionable, fide ten Hove & Kupriyanova 2009: 95), lacking a description for an operculum and the collar chaetae appear to be atypical.

The present, redetermined Serpula jukesii records of Potts (1928) and Fauvel (1933) from the Gulf of Suez are not enumerated among the ca. 16 species reported from within the canal.

Figures

FIGURE 11. Large spiralled serpulid tube. The tube was present in the test-tube labelled "Serpula vermicularis" by F.A. Potts but should rather be attributed to Hydroides heterocerus (The nominal "Serpula vermicularis" specimen collected by the Cambridge Expedition in the Gulf of Suez that was described in detail by Potts 1928 was no longer present [CUZM]). The abdominal uncini and chaetae shown below were found on skin still attached to the lumen of the tube. A—Upper view of tube (note spirorbid tubes encrusted on outer surface of the tube), B—Ventral view of tube, C—3/4 frontal view of tube, D—Abdominal uncinus, lateral view, F+5, E—Same, frontal view, left, F+10, F—Abdominal chaetae. Scales: A, B—5 mm, C—1 mm, D, F—10 µm.