Crustacea: Isopoda: Crinoniscidae
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Syst Parasitol (2020) 97:179–192 https://doi.org/10.1007/s11230-020-09903-x (0123456789().,-volV)( 0123456789().,-volV) A new species of Crinoniscus Pe´rez, 1900 (Crustacea: Isopoda: Crinoniscidae) parasitising the pedunculate barnacle Heteralepas newmani Buhl-Mortensen & Mifsud (Cirripedia: Heteralepadidae) with notes on its ecology and a review of the genus Lene Buhl-Mortensen . Jason D. Williams . Christopher B. Boyko Received: 10 August 2019 / Accepted: 12 January 2020 / Published online: 17 February 2020 Ó The Author(s) 2020 Abstract The new species Crinoniscus stroembergi articles 1 and 2 of the antennule being subequal in n. sp. belonging to the parasitic isopod family width and the anterodistal angle of antennule article Crinoniscidae Bonnier, 1900, is described from a being low and rounded; propodus of pereopods 6 and 7 pedunculate barnacle host collected in the Mediter- having a sinuous dorsal margin that is distally ranean Sea. This is the first species of Crinoniscus narrowing and the posterior margin of the pleotelson Pe´rez, 1900 described from a host in the genus being short and rounded. The mature females of Heteralepas Pilsbry. The male cryptoniscus larva is species in Crinoniscus are of two basic forms: those distinguished from congeneric species by having a with ventrolateral lobes on the pereomeres (C. dorsoventrally flattened body with the posterolateral alepadis (Gruvel, 1901) n. comb., and C. politosum- margins of the cephalon scarcely extending beyond mus Hosie, 2008) and those lacking such lobes (C. the anterior margin of pereomere 1 (in contrast to C. cephalatus and C. stroembergi n. sp.). The mature cephalatus Hosie, 2008 with extended margins); females of C. stroembergi n. sp. can be distinguished from other species of Crininiscus based on their lacking lobes on the anterior end. The material This article was registered in the Official Register of Zoological examined includes the male and three female devel- Nomenclature (ZooBank) as urn:lsid:zoobank.org:pub:CD58B03F-AF61-402D-AFA7- opmental stages of the parasite in the host, Heter- FA395D16F600. This article was published as an Online First alepas newmani Buhl-Mortensen & Mifsud. The article on the online publication date shown on this page. The mouthparts of the immature female are described article should be cited by using the doi number. This is the and the feeding biology and effects on the host are Version of Record. discussed along with a review of feeding modes in This article is part of the Topical Collection Arthropoda. species of the Cryptoniscoidea. Leponiscus alepadis is transferred to Crinoniscus; the latter genus now L. Buhl-Mortensen (&) contains five species. A modified diagnosis of Cri- Institute of Marine Research, Bergen, Norway noniscus is provided. e-mail: [email protected] J. D. Williams Á C. B. Boyko Department of Biology, Hofstra University, Hempstead, NY, USA C. B. Boyko Division of Invertebrate Zoology, American Museum of Natural History, New York, NY, USA 123 180 Syst Parasitol (2020) 97:179–192 Introduction hermaphroditism’’ where some larvae transform from males to females without fertilizing others. Cryptoniscoidea Kossmann, 1880 contains nine fam- Fong et al. (2017) stated that for Hemioniscus ilies of endo- and ectoparasitic epicaridean isopod balani Buchholz, 1866, the second cryptoniscus larva species associated with a diverse assemblage of to enter a host, fertilises the female and then leaves the crustacean hosts (Boyko et al., 2008 onwards); species host but we are unaware of any published data that in the genus Crinoniscus Pe´rez, 1900 (Crinoniscidae conclusively show males actually leaving the host in Bonnier, 1900) specialise in parasitism of sessile and which they performed fertilisation; in fact, it is clear in pedunculate thoracican barnacles (Hosie, 2008; Wil- Crinoniscus at least that males appear not to leave the liams & Boyko, 2012). The life-cycle of epicaridean host, given that up to six females and three males can isopods typically includes two hosts (e.g. Trilles, be found in a single host. It is not clear what the cue is 1999; Williams & Boyko, 2012), and the cryptoniscus that switches a larva from a male to female develop- larva is the stage that seeks out the definitive host. In mental trajectory; it may be that direct contact with the species of the Cryptoniscoidea, an adult female host leads to the female form while direct contact of develops from a cryptoniscus larva with male charac- the larva on a developing female maintains the male ters that metamorphoses in response to contact with an condition and triggers further testes development but appropriate host, but usually only if they are the first experimental studies are needed to settle this question. larva to encounter that host (Caullery & Mesnil, 1901; Bocquet-Ve´drine & Bocquet (1972a) indicated that Caullery, 1952; Blower & Roughgarden, 1987). young females (herein labeled as early immature Once triggered by (presumably) environmental females) are already fertilised but it is unknown when cue(s), the metamorphosing female dramatically fertilisation occurs (within the barnacle host or soon transforms into an adult that retains few isopod after settlement on barnacle prior to invasion of the characters and is sac-like in appearance and filled host). Present knowledge on the development from the with eggs or epicaridean larvae (‘‘environmental sex larva that encounters the host to the mature female determination’’ sensu Subramoniam, 2017). Unusu- stage is very limited for species in Crinoniscus, with ally among epicarideans, in species of Crinoniscus one the exception of studies by Bocquet-Vedrine & or more subsequent larvae encountering a host that Bocquet (1972a, b)onC. equitans Pe´rez, 1900 already is infested by a female parasite can also be associated with its host, Perforatus perforatus triggered to develop into females as well; a single host (Bruguie`re). can therefore contain several females in various stages Prior to the present study, there were three accepted of development. Some larvae that encounter a host species within Crinoniscus (see Hosie, 2008): Cri- already parasitised by a female (or females) do not noniscus cephalatus Hosie, 2008, C. equitans Pe´rez, metamorphose but retain the cryptoniscus larval 1900, and C. politosummus Hosie, 2008. However, appearance while the testes mature (i.e. they are Leponiscus Giard, 1887 (containing species also found neotenous). These functional males serve only to parasitising pedunculate barnacles) is not mono- fertilise the female; they do not parasitise the host phyletic if it contains L. anatifae Giard, 1887 and themselves. Thus, the form of hermaphroditism in L. alepadis Gruvel, 1901, because the latter species cryptoniscoids is different from the typical protandric should also be included in Crinoniscus. sequential hermaphroditism found in other epi- Giard (1887) placed two species in Leponiscus: carideans (e.g. Bopyridae); in cryptoniscoids, one or L. anatifae and L. pollicipedis Giard, 1887, but the more larvae with incipient male characters (present latter name is a nomen nudum. Giard (1887) did not but undeveloped testes) will turn into females without designate a type-species for Leponiscus, but only one fertilising other females (as opposed to most bopyrids of the originally included species is an available name, where all larvae will go through a functional male therefore L. anatifae is the type-species of Leponiscus phase with fully developed testes). Subramoniam by monotypy. Bocquet-Ve´drine & Bocquet (1972c) (2017) indicated that cryptoniscoids represent an considered L. anatifae a nomen nudum, making example of ‘‘normal intersexuality (as part of a life- Leponiscus an available name from Gruvel (1901) cycle)’’ but a more precise term for this reproductive rather than Giard (1887); this was followed by Hosie strategy would be ‘‘conditional protandric sequential (2008). Giard (1887), however, explicitly referred to 123 Syst Parasitol (2020) 97:179–192 181 figures in Hesse (1867) as representing L. anatifae and group, one that has been largely overlooked as egg L. anatifae is therefore available from Giard (1887) predators. (ICZN, 1999, Article 12.2.5). Except for the type- species, the only other valid taxon in Leponiscus is L. alepadis. It is clear from the illustrations of Hesse Materials and methods (1867), on which L. anatifae was based, that L. anat- ifae is close to if not identical with Hemioniscus balani Nine parasites, including two females, four juvenile (Hemioniscidae) whereas L. alepadis clearly females, and three males, were found inside a single belongs to Crinoniscidae (see Gruvel, 1901, 1902). specimen of Heteralepas newmani Buhl-Mortensen & No material from Hesse (1867), including the Mifsud, collected from a nylon mooring line in the specimens parasitising Lepas anatifera (Linnaeus) Mediterranean Sea off Malta at 35°51.3150N, that Giard (1887) based L. anatifae on, is known to 14°11.7070E (host: paratype specimen C in the be extant and the types of L. alepadis parasitising National Museum of Natural History, Mdina, Malta, Paralepas minuta (Philippi) are not present in the collection number NMNHC040a). The line was Muse´um national d’Histoire naturelle (MNHN). anchored in c.458 m depth, with its upper end drifting Because we lack material of either of these species, with the currents in the water column. The line became we take the conservative approach and retain entangled with a fisherman’s bottom long lines and Leponiscus as a valid genus within the Hemionisci- was brought up as by-catch; the barnacles were dae while transferring L. alepadis to Crinoniscus.If attached at the ‘‘top’’ of the line, corresponding to the antennular plate of the cryptoniscus larva is as 100–150 m depth. The size of the host specimen is shown by Gruvel (1902: plate 1, figure 3), then 1.02 cm (combined length of capitulum and peduncle) L. alepadis should be placed in its own genus; and was listed as ‘‘specimen C’’ in Buhl-Mortensen & however, it is equally possible that Gruvel Mifsud (2017). Isopod size is given as maximum (1901, 1902) misrepresented this structure as all length of females and males, anterior border of head to the characters of the female parasite (e.g.