Bijdragen lot de Dierkunde, 59 (4) 243-249 (1989)

SPB Academie Publishing bv, The Hague

A tantulocaridan Dicrotrichura tricincta gen. et spec. nov.: new (Crustacea:

Maxillopoda) from the Mediterranean deep waters off Corsica

Rony Huys

MarineBiology Section, Zoology Institute, State University of Gent, K.L. Ledeganckstraat 35, B-9000 Gent,

Netherlands Belgium and Delta Institutefor Hydrobiological Research, Vierstraat 28, 4401EA Yerseke, The

water Keywords: Tantulocarida, Dicrotrichura tricincta gen. et sp. nov., Mediterranean, deep

Summary small-sized maxillopodan genera Basipodella Beck-

er and Deoterthron Bradford& Hewitt, the number

The new genus and species, Dicrotrichura tricincta, is described of divided in nine species has raised to 17, at present from deep mud (1220 m) in the Ligurian Sea (western Mediterra- and five families Lincoln genera (Boxshall & 1987; nean). It is the first tantulocaridan not found to be attached to Huys in press). All tantulocaridanshitherto known a crustacean host but free living in the sediment. It is assigned

are of other crustaceans. to the Deoterthridae on the basis of the absence of a rostrum, obligate ectoparasites

the abdominal segmentationand the characteristic cephalic pore Most species show a high level of host specificity

pattern. It can be distinguished from all known tantulocaridans and utilize harpacticoids, tanaids or isopods as

in the presence of peculiar, bi-articulated caudal setae and the hosts although a few species are known to parasitize difference in thoracopodal setation between leg 2 and legs 3-5. ostracods and cumaceans. Boxshall & Lincoln Some new structures located on the attachment disc are

an excellent of the described for the first time. D. tricincta is the second tan- (1987) provide analysis highly

abbreviated life which tulocaridan to be recorded from the Mediterranean. cycle includes an infective

tantuluslarva, a swollen sac-like female and a free-

swimming male. Starobogatov's (1986) untenable Résumé

to the Tantulocarida proposal group (as a super-

Dicrotrichura tricincta n. n. le second Tantulocaride g., sp. est order Basipodelliformii) together with the gymno-

connu provenant de la Méditerranée. Il provient de la vase plean copepods in the infraclass Calanioini was re- profonde (1220 m) de la Mer Ligurienne (Méditerranéeocciden- jected by Grygier & Sieg (1988) and Boxshall & tale). D. tricincta est le premier tantulocaride vivant libre dans Huys (1989). The latter authors, inspired by the ho- le sédiment, et non attaché à un Crustacé hôte. L’absence d’un

of the male tantulocaridan rostre, la segmentationabdominale et le patron caractéristique mology penis, suggested des céphaliques le classent dans la famille des Deoterthri- instead pores that their relationships may lie with the

D. dae. tricincta se distingue de tous les Tantulocarides connus 'thecostracan group' of Maxillopoda which in- la de soies caudales bi-articulées différence par présence et par la cludes also the Ostracoda, Branchiura and Theco- entre la position et le nombre des soies sur les thoracopodes 2 et

straca Une (sensu Grygier, 1987). 3 à 5. description est donnée de structures nouvelles sur le Tantulocaridans disque d’attachement. are very uncommon in the Med-

iterranean but this should primarily be attributed

to the low levpl of sampling effort in this area, Introduction

rather than to any defined zoogeographical pat-

Since Boxshall & Lincoln (1983) formally estab- terns. The only mediterraneanfind thus far, consti- lished the class Tantulocaridato accommodate the tutes in fact the first record of a tantulocaridan,

* Contribution No. 452 of the Delta Institute for Hydrobiological Research, Yerseke. 244 R. Huys - Mediterranean deepwater Tantulocaridan

such. abdomen. however, without having been recognized as pedigerous somites, and a 2-segmented

In 1903 Bonnier described Cumoniscus kruppi on First thoracic tergite largely concealed beneath

of dorsal shield. the basis of a single specimen, obviously a female, posterior margin cephalic Cephalic

of ornamentation of 4 and referred the species to an unnamed family shield triangular; consisting an-

at surface lamel- epicaridean isopods. It was collected by dredging terior plus 6 posterior pairs of pores,

C. lae absent. curved in lateral 1000 m depth near the Isle of Capri, Italy. krup- Cephalic stylet slightly

found of view. 1 5 each pi was attached to an undescribed species Thoracopods to with unsegmented

Leuconidae and represents thus far the only pub- protopod bearing a well developed medial endite.

lished account of a cumacean-infesting tan- Exopod of thoracopods 1 to 5 apparently 1-seg-

unable tulocarid. Boxshall & Lincoln(1987) were to mentedwith 2 (leg 1), 3 (leg 2), or 4 setae (legs 3-5).

place the species in any of the existing families be- Endopod 1-segmented with 0 (leg 1) or 2 setae (legs

cause of lack of detailed information (Bonnier did 2-5). Thoracopod 6 without distinct rami, with

not give any illustrations) and because both the coupling spines on medial margin of protopod and

male and the tantulus are unknown. Hence, they 2 setae apically. Second abdominal somite with 3

sedis the somite. ranked Bonnier's species as incertae within transverse lamellae running around the

class and regarded the sac-like habitus and the an- Caudal rami distinct, armed with 1 short and 2

teriorly located, minute adhesive disc as sufficient long, bi-articulate setae. Host unknown.

evidence to keep C. kruppi in the Tantulocarida.

Most recently Boxshall (pers. comm.) found a sec- Etymology. - The generic name is derived from the

ond cumacean-parasitizing tantulocaridan, proba- Greek dikroös, meaning forked, trichos, meaning

from in tail bly belonging to Cumoniscus, deep water hair, and oura, meaning and refers to the

the Gulf of Biscay. peculiarly shaped, caudal setae. Gender: feminine.

tantulus from 1220 A single was caught m depth

in theLigurian Sea (western Mediterranean), repre- Type and only species. - Dicrotrichura tricincta

Deoterthridae senting a new genus and species of spec. nov.

described below. It is the first record of a tantulus

attached but stage not found to a crustacean host,

living free in the sediment. Description

Dicrotrichura tricincta spec. nov. (figs. 1A-B;

Methods 2A-E)

The holotype tantulus was examined as a temporary preparation Tantulus larva

in glycerin. All drawings were made under oil immersion using

a Leitz Dialux 20 microscope with interference contrast. Judi- Body (figs. 1A-B) comprising a cephalon covered cious manipulationof the coverslip allowed careful examination free and by a dorsal shield, 6 thoracic somites, a of the detailed morphology of the thoracopods and the cepha- 2-segmented abdomen. Totalbody length about 83 lon. After completing the description, the specimen was trans-

ferred to lactophenol mounting medium and the preparation /jm, measured from the tip of the cephalon to the

BDH was sealed with glyceel (Gurr®, Chemicals Ltd, Poole, posterior margin of the abdomen. Cephalon trian- England). gular, tapering anteriorly towards the oral disc;

posterior margin straight with posterolateral angles

Taxonomy represented by slightly pronounced lobes; ventro-

lateral margins with incision. Cephalic shield about

Dicrotrichura gen. nov. 1.14 times longer than wide (32 /xm X 28 ¿im); two

dorsal, longitudinal surface lamellae extend to the

Diagnosis. — Class Tantulocarida. Family Deoter- basis of the oral disc. The rostrum is absent. The

thridae. 6 oral disc is in diameterand is Tantulus larva comprising cephalon, about 8.5 /¿m posi- Bijdragen tot de Dierkunde 59 (4) - 1989 245

Dicrotrichura tricincta view Fig. I. gen. et sp. n. A, holotype tantulus, dorsal view; B, same, lateral (thoracopodal setae omitted). - 246 R. Huys Mediterranean deepwater Tantulocaridan

tioned far anteriorly so that it is visible in dorsal dite proximally, two spiny processes along the outer

the disc the dorsal distal aspect; is invaginated at midline, margin and two spinous processes at the outer

filament-like the lateral margins each have 3 struc- corner. Under light microscope a subapical spine

tures, the ventral margin forms a lobe-like exten- and a blunt process are visible on the edite. Rami

sion which is basally directed. A peculiar funnel- one-segmented. Exopod short, with two strong and

middorsal inci- shaped organ is discernible near the one (leg 2) or two (legs 3-5) slender naked setae.

sion of the oral disc; this slender, hollow structure Endopod one-segmented, long, with swollen basal

minute and further and thin-walled distal armed has a pore apically seems to run part a tapering part;

towards muscle-like strand which is with two setae with internally a outer-margin laterally; apex

in comparable both in appearance and position two processes, the outer one being spatulate.

with the striated organ mentionedin earlier descrip- Sixth thoracopod (fig. 2D) with simple protopod

tions. Internal structures other than the cephalic lacking medial endite, but bearing two coupling

stylet were too small for them to be described ade- spines on the medial margin; outer margin with 3

quately. There are 10 pairs of simple pores on the spinous processes. Rami not distinct but possibly

sides shield; 4 pairs in the anterior part (on both ar- represented each by a vestige bearing a strong

ranged in the typical deoterthrid L-pattern) and 6 naked seta.

of which is in pairs around the posterior margin 1 pair The abdomen(figs. 1 A—B; 2E) 15 /¿m length

is located subdorsally and another one surrounds a and two-segmented. The first abdominal somite is

of the covered 2.9 times wider than 3 the tiny sensillum; some pores were by long (8.7 /¿m x /¿m),

small bulb-shaped bodies of hyaline substance. The second 1.2 times longer than wide (12 /¿m x 10

ventral surface of the shield lacks pores and lamel- /xm). First somite without surface ornamentation.

lae altogether. There are no cephalic appendages. Second somite tapering anteriorly; ornamented

is about and with lamellae The cephalic stylet 22 /¿m long slight- 3 ring-shaped transverse giving the

curved both in dorsal and in lateral view. The somite Ventral ly tip a 4-segmented appearance. posteri-

of the stylet is extrudedand does not taperto a very or border of abdomen with two spinous processes,

fine point. The base is hollow and provided with covering paired combs consisting of several fine

two lateral barbs. spinules, the tips of which are not extending beyond

The six free thoracic somites each have well de- a rear margin of caudal rami; dorsal hind margin

the first five surface veloped tergite, lacking or- armed with two pairs of minute spinous processes.

the last with transverse surface namentation, one a Caudal rami very small, weakly defined; armed

lamella; except for the sixth one all thoracic somites each with one short lateral seta and two long medial

are equally broad and the thorax as a whole is dis- setae; medial setae consisting of strong basal part tinctly narrower than the cephalon. The first tergite with swollen basis and bifid apex with which the

is largely concealedbeneath the posterior rim of the slender, flagella-like, distal part articulates. cephalic shield. Each thoracic somite bears a pair of well developed thoracopods.

Adult male and unknown. Thoracopod 1 (fig. 2A) biramous, with a large female : undivided protopod bearing a lobate medialendite

rim Material. - A single tantulus found during sorting of at the proximal and a lobate proximal extension was

meiofauna from a sampling site (42°41'06"N, 08°38'30"E; at the outer margin. Endite armature visible as one. depth 1220 m) in the Ligurian Sea (western Mediterranean), spinous element (using light microscopy). The exo- northwest of the Bay of Calvi (Corsica). The bottom sample was pod is one-segmented and slightly longer than wide, taken on 18 September 1985 with asmall, modified Reineck box distal armed with 2 part two strong setae. Endopod corer (170 cm ) by Dr K. Soetaert. The median grain size of the

sediment is below 3 and the silt-clay 92%. represented by a digitiform segment bearing a small nm amount averages The CPE (Chloroplastic Pigment Equivalent)value is about 0.56 spinule. 2 /ig/cm of which 13.2% is representedby chl a. Accompanying Thoracopods 2 to 5 (figs. 2B-C) biramous, with meiofauna includes nematodes, harpacticoid copepods, for- large one-segmented protopod bearing medial en- aminiferans, gastrotrichs, annelids, loriciferans, sipunculids, - 247 Bijdragen tot de Dierkunde 59 (4) 1989

Fig. 2. Dicrotrichura tricincta gen. et sp. n., holotype tantulus. A, first thoracopod; B, second thoracopod; C, third thoracopod; D,

sixth thoracopod; E, abdomen, ventral view. 248 R. Huys - Mediterraneandeepwater Tantulocaridan

tardigrades, ostracods, kinorhynchs and turbellarians. The too small to be described adequately but their ab-

(Natural History), aid holotype is deposited in the British Museum sence in other tantulocaridans suggests that they

London. in holding the stylet in its central position during

penetration of the host's integument and degener-

- derived from the the internal tissue Etymology. The trivial name is ate immediately when reor-

Latin tres, tria, meaning three, and cinctus, mean- ganizes during metamorphosis towards the adult ing belt, and refers to the three transverse lamellae male or female. A peculiar funnel-shaped organ

of the adhe- on the second abdominal somite. was discerned near the dorsal margin

sive disc. Furthermore, both lateral sides of the disc

possess a series of 3 filament-likestructures. None

Discussion of these structures were observed during SEM ob-

servation of the inner surface of the oral disc of

Dicrotrichura tricincta is the smallest tantulocari- Boreotantulus kunzi (cf. Huys & Boxshall, 1988)

this based which had been dan recorded thus far, its body length (83 /xm) being but again was on tantuli less than half the size of the isopod-infesting Dory- successfully detached from the host. It is impossible phallophora megacephala (Boxshall & Lincoln). to homologise these 'oral' structures with cephalic

All other species that measure less than 100 /xm are appendages of other maxillopodans as Becker

known to parasitize exclusively harpacticoid cope- (1975) and Bradford & Hewitt (1980) have suggest-

pods: Basipodella harpacticola Becker (85 /xm), ed before. Being located anteriorly it is likely that

these function for detect- Stygotantulus stocki Boxshall & Huys (94 /xm), structures as sense organs

Boreotantuluskunzi Huys & Boxshall (98 /xm) and ing a suitablehost. This would explain their absence

Campyloxiphos dineti Huys (95 /xm). In terms of in attached specimens since the juvenile tantulus is

life till size harpacticoids represent the smallest host cat- believed to be attached permanently during

for that there the development is completed. Clearly, once firmly egory tantulocaridans, suggesting

of the host attached infective is able infect might be a relationship between the size the stage not to

infective suitable re-infest and the body length of the stage. another, possibly more host, or to

D. tricincta is also the only tantulocaridan that the same host at a different place on the integu- was found free in the sediment instead of being ment, because the muscles associated with the

firmly attached to a host. Potential crustacean cephalic stylet (penetration) and the thoracopods

hosts found in the same sample included harpacti- (locomotion) degenerate and/or are probably reor-

successful attachment. It coid copepods and ostracods but none of the speci- ganized immediately after mens were found to be infested, indicating that the follows that the detailed morphology of the tantu-

tantulus was not detached from the host's integu- lus is more complex than previously expected.

ment during the process of meiofauna extraction The new genus is placed in the Deoterthridae as

(centrifugation floatation technique; Heip et al., redefined by Huys (in press). The latter author ex-

of 1985). The cephalic stylet, unlike that of tantulo- cluded the isopod-infesting members the genus

and referred them caridans known from attached tantuli, definitely Deoterthron to a separate genus

the central of the oral adhe- in the established protrudes through pore Doryphallophora Huys newly sive disc. In D. tricincta the internal tissue The removal of these appears family Doryphallophoridae. to be arranged symmetrically around the stylet species solved the problematic status of Austrotan- which occupies a medial position in the cephalon. tulus Boxshall [= Deoterthron] (Boxshall, 1988;

In previous descriptions the stylet is often reported Huys & Boxshall, 1988) and narrowedconsiderably

wall of to lie near the ventral the head and some- the familial diagnosis of the Deoterthridae, now

its orientation within Boreotantulus & times varies the same species embracing Deoterthron, Huys

(Doryphallophora harrisoni for instance; cf. Box- Boxshall and Campyloxiphos Huys. The genus Di- shall & Lincoln, 1987). The internal structures lo- crotrichura can easily be included in this series be-

include the cated aroundthe piercing organ of D. tricincta were cause of its juvenile characters. These - Bijdragen tot de Dierkunde 59 (4) 1989 249

absence of a rostrum, the cephalic shield with 10 Acknowledgements

of pairs pores (4 anteriorly, 6 posteriorly), the

of 2 on the of presence setae exopod 1 and the Grateful thanks are due toDr Karline Soetaert for leg providing me

abdomen. The detailed with the tantulocaridan material. two-segmented arrange- Part of this research was car-

ried under EEC Science Grant of the is the out No. ST2*0443. ment cephalic pores exactly same as

described for other deoterthrid genera and rein-

forces the significance of this character in diagnos- References ing higher level taxa in the Tantulocarida(Huys, in

press). The presence of small bodies of substance

extruded from Becker, K.-H., 1975. Basipodella harpacticola n.gen., n.sp. some of these pores might indicate (Crustacea, Copepoda). Helgol. wiss. Meeresunters., 27: their secretory role. 96-100. The bi-articulated caudal setae, showing a junc- Bonnier, J., 1903. Sur deux types nouveauxd'Épicarides para- tion between the furcate and the dis- sites d'un C. proximal part Cumacé et d'un Schizopode. r. hebd. Séances

tal flagella, are unique to Dicrotrichura. It is wor- Acad. Sci. Paris, 136: 102-103.

1988. A Boxshall, G.A., new of tantulocaridan thy to note that the caudal setae of Campyloxiphos genus (Crustacea: Tantulocarida) parasitic on a harpacticoid cope- dineti show a slight swelling at about the same site pod from Tasmania. Bull. Brit. Mus. (nat. Hist.), D54: of this articulation. In all known tantulocaridans 270-274.

the setation is identical on 2 to thoracopodal legs 5 Boxshall, G.A. & R. Huys, 1989. New tantulocarid, Stygotantu-

but in Dicrotrichura the second thoracopod is lus stocki, parasitic on harpacticoid copepods, with an analy-

sis of the differentfrom 3-5. The differs phylogeneticrelationships within the Maxillopoda. legs new genus also J. crust. Biol., 9: 126-140. from the other Deoterthridae in the ring-shaped Boxshall, G.A. & R.J. Lincoln, 1983. Tantulocarida,a new class lamellae on the second abdominal somite. Cam- of Crustacea ectoparasitic on other crustaceans. J. crust. and pyloxiphos Boreotantulus exhibit a similar ab- Biol., 3: 1-16.

dominalsurface ornamentationbut here the lamel- Boxshall, G.A. & R.J. Lincoln, 1987. The life cycle of the Tan-

tulocarida (Crustacea). Phil. Trans, r. Soc. London, B315: lae are arranged transversely only in dorsal aspect; 267-303. however, laterally and ventrally they are joined by A Bradford, J.M. & G.C. Hewitt, 1980. new maxillopodan short longitudinal lamellae. No distinct surface crustacean, parasitic on a myodocopid ostracod. lamellae found in both were Deoterthron species. Crustaceana, 38: 67-72.

D. tricincta is similar to C. dinetiin the setation of Grygier, M.J., 1987. New records, external and internal anato-

and the 3rd my, systematic position of Hansen's y-larvae (Crustacea: to 6th thoracopods. The new species how-

Maxillopoda: Facetotecta). Sarsia, 72: 261-278. well defined ever, possesses a asetose endopod on M.J. Grygier, & J. Sieg, 1988. Microdajus (Crustacea: Tan- leg 1 and an almost straight cephalic stylet whilst Antarctic and tulocarida)parasiticon an tanaidacean, a range

the latter exhibits a uniramous first extension thoracopod (en- of M. langi Greve. J. nat. Hist., 22: 1495-1505.

in combination M. dopod absent) with an unusual sig- Heip, C., Vincx & G. Vranken, 1985. The ecology of marine

moid The of nematodes. Oceanogr. mar. Biol. ann. Rev., 23: 399-489. stylet. presence 5 setae on thoracopods in Huys, R., press. Campyloxiphos dineti gen. et spec. nov. 2 to 5, the slightly ornamentend abdomen and the from off Namibia and a redefinition of the Deoterthridae lateral, serrate, caudal serve to spine distinguish Boxshall Lincoln & (Crustacea: Tantulocarida). J. nat. Hist, Deoterthron from Dicrotrichura. Boreotantulus (in press).

differs from the in Huys, R. & A new genusprimarily the unusual G.A. Boxshall, 1988. new genus and species of

tantulocaridan (Crustacea: exopodal setation of the thoracopods, showing Tantulocarida) parasitic on a har-

pacticoid copepod from the Skagerrak. 73: 205-211. 2 Sarsia, only setae on legs 2-5 but 3 setae on leg 1. The Starobogatov, Ya.I., 1986. Systematics of Crustacea. Zool. Zh., familial allocation currently suggests that D. 65: 1769-1781. [In Russian, with English summary.]

tricincta parasitises either harpacticoids or os-

tracods. Received: 27 September 1989