THE VELIGER

The Veliger 50(3):2 19-224 (O ctober 1, 2008) © C MS, Inc., 2007

Dendropoma mejillonensis sp. nov., a New of Vermetid () from Northern Chile

ALDO PACHEC0 1,* AND JÜRGEN LAU DIEN 2

I U niversidad de A n tofagasta, Facultad de Recursos de l M a r, Av. A ngamos 60 1, PO Box. 117, Antofagasta, 2 Al fred Wegen er Institute for Polar and Marine Re sea rch, 0-27568 Brernerhaven, Germany

Abstraer. D endropoma m ejillonensis sp. nov. is described based on rno rph ology fo r the first tim e. This vermetid gastropod inhabits the rocky su btidal zone o f Peninsula Mejillones in no rt hern Chile. In Ju! y 2006 , specimens were collected by SCUBA diver s frorn the rocky " Anemones Wall" (23°28' I7.30"S, 70°37' I3.80"W) at 17m depth. The morphol ogy of D. m ejillon ensis is d istinguished fr om tha t of other mem bers of the fami ly by its poin ted lip on the extern a! border of the protoconch an d the two whi te bands on the head tentacles. This ex tends the geographica l range of the genu s Dendropoma into the Southeastern PacificoThe present species D. mejillonensis is th e only known vermetid gastropod abl e to thrive under the cold upwelling cond itio ns of the H umboldt Curren t ecosystem off northern Chile.

INTRODUCTION opercu lu m is well developed and equal in diameter to the a pe rt ure . A t present, the ge nus Dendropoma covers Ma rine gas tropods of the famil y a re sessile int ertidal and su blittoral species and can be gregarious organisms wit h an irregul ar, uncoiled shell providing a or solitary . So far, th e most comprehensive infonnation three-dimension al biogen ic habitat for associated about Dendropom a spp. is p rovided by species. Their dis tribution is restricted to tropical a nd H ad field et a l. (1972) for specimens found o ff Hawaü. subtrop ical latitudes (Me xico, Californ ia and West Informat ion on th e distribution of vermetids off Africa) as well as to locati ons in the warm M editerra­ co ntinenta l Chile an d its offsh ore islands is scarce an d nean Sea (K een, 1961, 1971 ; Schi ap arelli et al., 2003). the taxon omic sta tus is still uncertain (Rehder, 1980; Habitats are rocky intertid al and subtidal zo nes with R amírez & Osorio , 2000; R . Bieler pe rs. comm .). In warm and oxy genated waters (Keen, 1961; Calvo et a l., fact , extensive reviews of gas tr opod taxonomy an d 1998). Due to the irregular tu be fo rm , taxonomic studies of invertebrate biog eographic pattern s av ailable ide ntifica tio n has co mmonly been co nfuse d wit h fro m thi s coast do not me n tio n th e family in the region Vermicularia () (Bieler , 1996) and Serp ulid (Marincovich, 1973; G uzmán et al., 1998; Brattstr óm & polychaetes (Keen, 1961, 1971) resulting in a confuse d Joh anssen, 1983; Valdovinos, 1999; Lancellotti & taxon omic status. The morph ological cha racters V ásq uez, 2000). A necdota lly, vermetids have bee n deemed useful fo r taxonomic ide ntificatio n have observed associated with hold fasts of the ke lp L essonia changed over time (Bieler, 1995; Sch iap arelli & trabeculata Villouta & Sa ntelices, 1986 off centra l C hile Métivier, 2000) . A genetic study fur ther conclud ed th at (Vásq uez & Veg a, 2004) . W ith the excepti on of the disjunct popuJ a tions o f Dendropoma species are close latter obse rva tio n, there is no published evide nce from phylogenetic relatives (Rawlings et al., 200 1), thu s th e Ch ilean co ast. Nonetheless, Dendrop oma platyp us suggesting th at taxonomic detennination shou ld be M órch , 186 1; Dendropoma spp. and S erpulorbis Sassi, approached ca re fully. 1827 have bee n recorded from Easter Island (Rehde r, The Dendropoma (M órc h, 1861) was rev iewed 1980; R ami rez, 1987; Va ldovinos, 1999) an d Serpulor­ by K een (1961 ) on the basis of 10 species dis tributed bis sp. wa s also observed at R obinson C ru soe Island among tropical an d sub tropical locations. Distinctive (Juan F ernández arch ipelago) (R amírez & Osorio, rnorpho logical characteristics for thi s ge nus are pla­ 2000), both insular Chi lea n locati ons. oorboid early who rls th at become mo re loosely coiled Northern Chile forms part of the Humboldt Curre nt _ in lat er stages; and th e scu lpture of lamellar growth­ u pwelling ecosystem, which is characterized by year­ striations that may or may not be in tersected by round high levels of pri mary produc tion du e to wind­ lon gitudinal lines, sinuous and risi ng toward a crest driven co ld upwe lling water , which re tur ns nutr ien ts to near the outer edge of the whorl in most spe cies. T he th e eu photic zone (Barber & Smith, 1981). There is a shallow oxygen minimum zone (OMZ) and on ly the Te!.: 056-55-637404, Em ai l: babucha [email protected] upper 40 m are well oxygena ted (Arntz et a l., 2006). Page 220 The Veliger, Vol. 50, No. 3

70" 30' Peninsula

Mejillones 22"30'

Pacific Ocean

23" 45' A o= B e ,lO'37'13,80"

Fi gure 1. A. Sampling loeation " Anemo nes Wall" (23°28' 17.30"S, 70°37' 13.80"W) opposite tbe southeastern side of Isla Santa Maria. B. Peninsula Mej illone s. C. Di stributional range of reJated vermetid speeies (a) Petalonchus innumerabilis (b) Serpulorbis squamigerus (e) Vermetus compta (d) Dendrop oma rastrum (e) Serpulorbis sp. (1) Dendropoma platypus.

This habitat is very different from that of warm-water embedded; coiling planorboid in early whorls, becom­ subtropical and tropical vermetid species. lo this study ing looser in later whorls, with tendency toward right­ Dendropoma m ejillonensis sp. nov. is described from angle turns. The of the adult is mostly white, Peninsula Mejillones, a location within thi s particular intennittently stained with dark brown, especially upwelling system. A detailed morphological character­ within. The sculpture of lamellar growth-striations, ization is provided. that may or may not be intersected by longitudinal lines, is sinuous and rises toward a crest near the outer MATERIAL AND METHüDS edge of the wborl in most species. Two nuclear whorls are dark brown in color, inflated, smooth to malleated Individuals of Dendropoma mejillonensis sp. nov. or axially ribbed, and the aperture lip is pointed or colonizing a vertical rock wall in the subtidal zone claw-like in sorne species. The operculum is well (17 m depth) of Peninsula Mejillones (23°28' 17.30"S, developed, as large as the aperture, its inner surface 70°37' 13.80''W) were pbotographed and collected by having a distinct central att achment scar that is SCUBA divers on July IIth , 2006 (Figure lA, B). somewhat button-like, and its exterior composed of Several vermetid clusters were scratched from the rock chitinous pIates in a spiral arrangement, either com­ with a knife and maintained in the laboratory for pactly welded to form a smooth surface or variously observations. Measurements were taken with a digital agglutinated with foreign materials. caliper or by using calibrated eyepieces on a dissecting microscope. Photographs were taken with a Canon Dendropoma mejillonensis sp . nov. Power Shot S50 camera connected to a binocular microscope Olympus SZ61. were anesthetized Type locality: Live-taken syntypes collected from a by adding methanol drops in the small examination large aggregation colonizing Anemones wall at 17m containers before sacrificing. Soft bodies were removed depth, Peninsula Mejillones, northem Chile (23°28' 17.30"S, from the shell after cracking with a small clamp. Gross 70°37' 13.80''W) were deposited in the Field Museum of anatomy of the soft parts wa s stud ied under a N atural History, Chicago, Illinois, U .S.A. (FMNH N °­ dissection microscope. Air-dried shells, radula, proto­ 312172 and N °-312173). Additional samples were conch and opercula were observed and photographed, deposited in the Museo Nacional de Historia N atural using the scanning electron microscope lEOL, model de Santiago de Chile (paratype MNHNCL N °-5159 and JSM- 6360LV. syntypes MNHNCL N °-5160, 5161 , 5162) Teleoconch (Figure 2a, b): The tubes form continuous Diagnosis and compact colonies, which are grey to faintly green in the field , but white after cleaning. In situ, the tubes are Genus Dendropoma M órch 1861 slightly nested in the rocky substrate. The attached part Solitary to colonial forms, corroding a trench in the of the tube appears eroded, and thus is thinner substrate, in which the lower part of each volution is (Figure 2d). The aperture is circular and its mean A. Pacheco & J. Laudien, 2007 Page 221

Figure 2. Dendropoma m ejillonensis sp. nov. (a) Mass of livin g ad ult tubes. (b) Lat eral view (e) Teleconch of ju veni1e showing co neentric growth striations. (d) Smooth eroded part showed fro m the attached part of th e tu bes. (e) Opercul um dor sa l view , (f) Operculum ven tral view. (g) Proto conch a pertu re. (h) Prot oeooch; detail of the sculpture and poioted lip-l ike ex ter nal border. (í) Protoconch in ventral positi on, the earliest who rJ is noted. (j) R adula displacem ent. (k) Detail of the cusp o n th e marginal teeth. (1) View of the anima l head, the arrow points to the distinctive white mark. diameter in adults is mm (SO = 0.37; n = 16). The th e ma r. The coil ing pa ttern is varia ble. Early whorls tube exhibits sinu ous gro wth lines and the sculpture of are like Planorbidae, co iling counterclockwise, fol­ lamellar growth-striations is not intersected by longi­ lowed by a very loo se coiling or irregular pattern. The tudinallines (Figure 2c). The periostracum is white and shell o f th e juvenile is wh ite and tr anslucent with clear the intermediate layer slightly cream. Observing from a axial rib s (Figu re 2c). cross-longitud ina l sectio n, three layer s of the conch a re present. The interior part is cream porcelain, d arker Operculum (Figure 2e, f): The form is circular and towards th e interior tube. Very soft lon gitudinal lines concave, slightly flattened and reddish in the center, are only observed under magnification. There is no brown-oran ge to col orl ess towards th e extern al border. internal shell lamellar struc ture. The proximal part of The diam eter is 2.7 mm (SO = 0.2; n = 10) in adult the tube slightly tends to vertically rise fro m the rest of specimens a nd about 1/5 of the len gth of the relaxed Page 222 The Veli ger , Vol. 50, No. 3

ped al disk diameter. The opercu lu m is composed of co nce ntric layers of chitinous mat eri al with visi ble concen tric irregula r line s, not ably in j uveniles. The small m amilla is inserted in the peda l surface. Almost 90% of th e studied opercula wer e fouled with b ryozoans.

Protoconch (Figure 2g, h, i): Globular, brown o r co lo rless, white towards th e earliest whorl. The she ll shows 1 to 1.5 nuclear wh orl s, o rnamented with longitudinal groo ves. The gro oves sho w no ev ident a xia l pattern , are va riable in size and p resent a slightly rec ta ngular o r tri angul ar shape with no marks a t th e co rn ers . T he ex ternal borde r presents a pointed lip shape and gro wths stria tio ns are presento At ha tching, she ll leng th (the distance from the externallip border to th e o pposite who rl ma rgin ) is 0.77 mm (SO = 0.07 ; n = 10). Figure 3. Capsules of Dendropoma m cjillonensis sp. nov. contain ing ju veniles (arrow left side) and nurse yo lk (a rrows Radula (Figure 2j, k): T aenioglossan type, sim ila r to righ t side). the de scription of o ther ver me tids (i.e., Vermetus triquetrus Bivona-Bernardi, 1832 and Thylaeodus rugu­ columellar muscle appears as a white triangul ar na rr ow losus M onterosato, 1878; Bieler, 1995), tran sparent, strip , ena bling the to retreat deeply into its she ll. co ns isting o n average of 39.8 (S O = 6.06) rows of teeth Fernale's brood s comprise three to four egg capsul es, (co unts a nd me asu rements based o u ad ult animals of which are ovoid a nd the membrane is tr an slu cent. Each 4 mm sh ell aperture, n = 10, no d ifferences between capsul e conta ins between three to ten j uve niles. Early sexes were noted). Tota l len gth of radular rib bon is capsules conta in nurse yolk (F igu re 3). Feeding is 2.35 mm (SO = 0.34) a nd 0.196 mm wid th (S O = carried o ut by l11U COUS threads. 0.0 11, m id ribbon). A trapezoidal rac hidian tooth with Habitat: The specimens we re attached to a vertical ro ck a stro ng main cu sp a nd 4-5 flanking cups on either side wall, which extends from the shallo w subtidal down to (di minishing towa rd margin), basal denticles stro ng ly 50 m depth. In the field , co lonies showed a lig ht grey to developed. Lateral tooth cus p a rrangement o f triangu­ white co lo r a nd were commonly fouled by calcareous lar cutting shape, as in th e central tooth, with tw o algae ca using a red/purple colorat ion. The snrroundi ng flanking cu sps o n eithe r side . The inner margin al tooth benthic community is dom inated by th e kelp L essonia is slender with a stro ng ma in cusp and th e inner trab eculata frorn 13 m depth down to 25 m. Below m a rginal with one flanking cus p on insi de and two on 25 kelp a bundance is substantially reduced a nd outs ide. The outer marginal teeth p resent a sin gle rel ati vely small epibenthic taxa suc h as calcareous a lga e flanking cusp smooth on o utside . R adular formula : (Lythothamniotn sp . a ud Lithophyllum sp.), red a lgae 2+I+R+ I+ 2. (Rhudymenia corallina Bory de Saint Vince nt & Animal: R emoved from th e shell tbe body is short and Greville), bryozoans (lvfem branipora isabellcana O 'Or­ narrowest to wards th e term inal part, which is sligb tly bign y, 1847 and Lagenicella variabilis M oyano, 1991) , co iled . The average len gth of relaxed la rge ad ult a nd Po rifera cover the su bstrate. Dendropoma mej illa­ spe cimens is 18.6 6 mm (SO = 1.68; n = 10). T he head nensis sp. nov. colonies were observed betw een 15 and is mainly light grey o r reddish with black, white an d 25 m. ye llow specks. The posterio r part is reddish or da rk E tyrnology: The species is narned Dendropoma mejillo­ brown in color. T wo white bands o n the he ad tentacles nensis in reference to the di scovery location Pen insula are distinctive appearing as a wh ite eyebrow (Fig­ M ejillones. ure 21). T he head tentacles are br o wn o r light grey in colo r with black a nd yell ow dots, no distinctive marks a t the tips a re visible. The pedal tentacles are light grey DISCUSSION with ye llow specks. In both sexes th e light orangel T axonomic remarks mel on mantle is entire a nd is characterized by a light brown border. The foot is a sim ila r color to the mantle; The morphological classi ficat ion of the species to th e however it has a white band around the opercu lum Dendropoma genus was carri ed out following Keen insertion. The gill filarn ents are a bout 1/3 of the size of ( 196 1). D endropom a m ej illonensis sp . n ov. shows the m antle and slightly triangula r in shape. The simi larities to Dendropoma gregaria H adfield & Kay, A . Pacheco & J. Laudien, 2007 Page 223

1972 (H adfie ld et al., 1972) fro m H awaii , sha ring the facilita ting the supply o f sessile species to new regions circular pattern in the o perculum and den se white (Thiel & H aye, 2006). A gene tic st udy is necessary to pigmentation aro und the eyes . T he mo st notewo rthy revea l linkages between D. m ejillonensis and oth er difference is in the protoconch sculpture, while D. vermetids. gregaria has light axial rib s cross ed by filler spiral striations, D. m ejillonensis shows so ft groo ves without Acknowledgments. We are grateful 10 Christia n Guerra and evide nt design sha pe and pattern. Ivan Marin for their suppor t durin g divi ng. Martha Ca lvo provided useful litera ture. José Ri ascos, O laf Heilmayer, R icard o Guiñez are thanked for their suggestions on an Distributional Remarks earlier version of the man uscript. Carrie Auld and Ruth Alheit kind ly edited t he Englisb. Pabla Veg a helped with the SE M As already mentioned, the pr esence of vennetid p hotogra phs. R üd iger Bieler provided taxonomic adv ice. We gas tropods is limited along th e Pacific coa st of South a ppreciated the co m me nts made by two a nonymous reviewers. This stu dy was co nd ucted in the framework of th e E U-funded America. Alamo & Va ldivieso (199 7) reported Pe ta lo­ IN CO project , " Clima te Variability and El N iño-Souther n conchus innum erabilis Pilsb ry & Olsson 1935 fro m Oscilla tion: Implications for N at ur al Coastal Resources and M azatlán (Mexico) to Bocapan and Huacho (Peru), M anagement" (CENS OR ) and Programa Bicentenario de S erpulorbis squam igerus Carpenter, 1857 from San C iencia y Tecnología This is C EN SOR publication Diego (California) to Pa ita (Peru) and Vermetus N° 34 1. comp ta Carpenter, 1857 from Briti sh Colum bia (Ca­ na da) to Pa ita. Keen (197 1) recorded Dendropom a LITERATURE CITED lituella M órch , 1861 and Dendropoma rastr um M órch, A LAMO, V. & V. VALDIVIESO. 1997. Lista siste mática de 1861 from the northern part of the Eastern Pacific; mo lu scos marinos del Perú. Instituto del Mar del Perú, both were fou nd from southern California to the 183 pp. southern Gulf of Californ ia at La Paz, Baja Califo rn ia W. , V. GALLARDO, D. G UTIÉRREZ, E. ISLA, L. (see also Figure l c). LEVIN, J. C. NEIRA, G . T. ROWE, J . T ARAZONA The presence of Dendropom a mej illonensis in the & M . WOLFF. 2006 . El N iño and similar perturbation rocky subtida l zo ne of Peninsula M ejillon es clearl y effects on the benthos of th e Humbo ldt , Califo rn ia and Ben guela curren t upwelling ecosystems. Ad vances in extends the gecgrap hic range of the family into the Geoscience 6:243-265. So utheastern Pacific, almost 2000 km southwards. BARBER, R. T. & R. L. SMITH. 198 1. Coastal Upwelling According to th e literature the closest distribution limit Ecosystems. In : A . R . Longhurst (ed .), An alysis of of vermetids is Huach o (1I06'56.2 1"S, n 037' 9.46"W) Marine Ecosystems. Acade mic Press. P p. 31-68. (Ala rno & Va ldivieso, 1997). Easter Island and Ju an BIELER, R . 1995. Ver me tids gastropods fro m Sao M iguel , Fernández may be so urce locat ions if Dendropoma sp . Azores: Comparative an at om y, systematic position and is D. m ejillonensis, in thi s case the range would be biogeographic affiliation. Acoreana , Supplement. 173­ 192. extended from insular to continental Chile. H owever, it B1 ELER, R. 1996. M órch's worm snail taxa (Caenogastropoda: is not possible to define the b iogeography of this Ver metidae, Siliquariidae, T urritellidae). Am erican Ma­ species, as we d id not sam ple sou th or north of the type lacological Bullet in 13(1/2):23-35. locality. BRATISTRDM, H . & A. JOHANSSEN. 1983. Eco logica l an d Ou r record provides evid ence that D. m ejillonensis is regional zoogeogra phy of the marin e ben thic fauna of able to th rive under cold u pwelling condition s. The C hile. Sarsia 68:289-339. CALVO, M., J. T EMPLADO & P. E. PENCHASZADEH. 1998. observed recruitment at Anemon es Wall (A. Pacheco Reproductive biology of the gregarious medi terra nean unpublished dat a) indicates that this species has the gas tropod , Journal of the Marine capacity to adapt to cold up welling co nditio ns. The Bio log ical Associatio n of the Uni ted Kingdom 78:525­ spec ies' di stribu tion may be limited by th e presence ofa 549. sho rt larv al stage. As in the case of man y other CAMUS, P. A. 2001. M arine biogeography of continental vermetids (Keen , 1961; Had.field et al., 1972; Calvo et C hile. Revi sta Chi lena de H ist oria Natural 74:587- 617. al., 1998), larvae of D. m ejillonensis leave the female GUZMÁN, N., S. SAÁ & L. O RTLIEB. 1998. Descriptive catalogue of nearshore mo lluscs (Gastro po da a nd Pele­ mantle cavity well developed a nd crawl around for less cypoda) fro m An to fagasta a rea, 23°S (C hile). Estud ios th an one hour before cem enting themselves to the Ocean ológicos 17:17- 86. substra te. T he recent d iscovery fro m Península M ejil­ M . G ., E. A. M . U . G ILLETTE & M . C. lones suggests th at sever al unexpl ored areas with LLOYD. 1972. T he Verrnetidae ( : Gastropod a) of unreported spec ies may still exist along the northern the Hawaiian Islan ds. Marine Biology 12:81-98. Chilean coastline, particularly in zones d ifficult to KEEN, A. M. 1961. A proposed reclassification of the gas tro pod family Verrnetidae. Bu lletin of the British reach (Camus, 200 1). Furthermore, distributions of Museum (Natura l H istory) Zoology 7(3):181-213. raftin g species (a d ispersal mech ani sm suggested for KEEN, A. M . 1971. Sea shells of tropical wes t A merica . vermetids (Bieler, 1995)) may cxtend qui ckl y with an M a rine mo llusk s fro m Baja California to Perú. Stan ford increasing arnount of anthropogenic floating material, Uni versity Press: Stanford, California. 1063 pp. Page 224 The Veliger, Vol. 50, No. 3

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