Notes on West African Perrona (Gastropoda : Clavatulidae), with the description of a new species

2008·6.9 MB·English

by  Emilio Rolán

©
SociedadEspañola deMalacología
Notes onWest African Perrona (Gastropoda: Clavatulidae),
with the description ofa new species
Notas sobre Perrona (Gastropoda: Clavatulidae) en Africa
Occidental, con la descripción de una nueva especie
Emilio ROLÁN*, Peter RYALL** andJuan HORRO***
Recibidoel31-VI1-2007.Aceptadoel19-X-2007
ABSTRACT
The type species of the genus Perrona is poorly known and given an erroneous type local-
ity. One of the purposes of this paper is to clarify its status and correct spelling as well as
illustrating the species and defining its distribution area. A new species from Angola
belonging to this genus is described. The shell, protoconch, operculum and radula are
illustrated, and the reasons for assigning this new species to this genus are discussed. All
known species of Perronaare figured.
RESUMEN
La especie tipo del género Perronaes poco conocida y la localidad tipo dada es errónea.
El objetivo de este trabajo es clarificar su situación, su correcto nombre, además de repre-
sentar la especie y clarificar su área de distribución. Se describe una nueva especie de
este género de Angola. Se muestran concha, protoconcha, opérculo y rádula de la nueva
especie y se discuten las razones para asignarla a este género y no a otros con similar
morfología. Se ilustran todas las especies conocidas de este género.
KEYWORDS: Clavatulidae,Perrona,WestAfrica,Angola, newspecies.
PALABRASCLAVE: Clavatulidae,Perrona,Áfricaoccidental,Angola,nuevaespecie.
INTRODUCTION
Classical malacological works like Their generic placements and syn-
Bruguiére (1792), Lamarck (1801, 1816 onymiesarestillnotclear. Somemodem
and 1822), Kiener (1840) and Reeve works like Knudsen (1952, 1956),
(1843, 1845) and publications dealing Ardovini (2004), Boyer and Hernán-
with Turridae (s.l.) such as Récluz dez (2004), Nolf (2006), NolfandVer-
(1851),PetitdelaSaussaye (1851),von straeten (2006) and Boyer and Ryall
Maltzan (1883, 1884), Sykes (1905), (2006) have described new species or
Dautzenberg (1912), Strebel (1912, revised others, placing most of them in
1914) have described numerous West thegenusClavatula.
African species assigned to the family Among our material from Angola,
ClavatulidaeGray, 1853. dredged over many years by Xico Fer-
*MuseodeHistoriaNatural,CampusUniversitarioSur,E 15782SantiagodeCompostela,Spain
**St. Ulrich 16,A-9161 MariaRain,Austria
***MonteroRíos,30-3°36201 Vigo,Spain
5
Iberas, 26 (1), 2008
nandes, a new small unidentified species when he included it in a list of
specieswas found. Its descriptionis one North-west African shells which he
of the subjects of this work. The generic stated carne "from Madeira to the Gulf
attribution to the genus Perrona (Schu- ofGuinea".
macher, 1817) requires a review of the Tryon (1884), although stating his
typespeciesbecauseitis a ratherpoorly Opinión that this species was an inter-
known species. This paper therefore medíate form between lineata and
alsocommentsonthetypespecies. spirata, mentioned it as Clavatula (sub-
genus Perrona perron Chemnitz and
)
TheidentityofPerronaperron providedadetaileddescription.
Martini and Chemnitz (1788: 278, Strebel (1912), in his revisión of
pl. 164, figs. 1573, 1574) illustrated a genus Perrona, treated as clearly differ-
shell they named "Der Perron". Later ent species both spirata and perron. He
Gmelin (1791), referring to Chemnitz's was able to examine Chemnitz's speci-
figures, described itasMurexperron and men from which the famous drawings
indicated "in Océano australi" as its were made and reillustrated it. He
geographic origin. This type locality is referred immature specimens of the
obviously wrong. These figures, or the species to Reeve's description, calling
shell they represent, can be considered themperron var. reevei. He also correctly
to be the lectotype. Its present where- indicated part of the correct habitat
abouts,asnotedbelow,areunknown. rangeofthespecies,citingspecimenshe
When Lamarck (1816) described had examined from Pointe Noire,
Pleurotoma spirata he also made refer- CongotoAmbriz,northemAngola.
ence to the same illustrations, but sepa- Knudsen (1952) employed the ñame
rated his species from them by stating "Clavatula perronii (Reeve)" noting that
"Lafigure citée de Chemnitz offre sur la the "Atlantide expedition" could not
base du dernier tour des sillons dont notre obtain any additional material and that
;
coquilleestabsolutementdépourvue". Chemnitz's type could no longer be
Schumacher (1817) also referred to tracedattheZMUC.
thesameillustrations ofChemnitzwhen Powell (1966), who referred cor-
hedescribedthegenusPerronaandnomi- rectly to the type species ofPerrona, did
natedPerrona tritoniumasthetypeofthis not figure Perrona perron but illustrated
genus. P. tritonium is therefore a júnior Perronaspirata (Lamarck, 1816).
objective synonym of Perrona perron More recently, Cernohorsky (1974)
(Gmelin).Againnolocalitywasgiven. figured a syntype from Chemnitz (in
The species was subsequently ZMUC), commenting that "the species
describedforathirdtimebyReeve(1843) most probably Uves in West Africa but this
who referred once more to Chemnitz's localityhas been not substantiated byeither
illustrations. He gave ittheñamePleuro- literature records or authentic specimens.
toma perronii, drawing his own figure Anotherpossibilityis thatMurexperronis
fromhis own shell. He likewise did not conspecific with Pleurotoma spirata
State a locality or habitat. Reeve cited Lamarck, 1816, as suggested byNordsieck
Lamarck's spirata as a different species, (1968: 154) although the two species appear
writing "1havea shell before meofverydif- quitedistinct".
ferent character (Pleurotoma Perronii, Finally, Bernard (1984, fig. 182)
nobis), answering exactly to thefigure in figured under the erroneous ñame
question". Reeve (1843) did not cite "Clavatula kraepelini" three specimens of
Gmelin and therefore appeared to con- this species. He unknowingly extended
sider his ñame as a valid new species. Strebel's habitat range northwards,
Howeveritisclearlyajúniorsynonymof quoting the localities ofboth Cape Este-
Gmelin'sspeciesanditisconcludedthat rias and Mayumba in Gabon, and indi-
thiswasanomissioninReeve'swork. catingadepthof-20to-50meters.
Marrat (1877) was the first to give After examining Reeve's type speci-
an indication of the true range of the men, the available literature and some
ó
RoláNETAL.: Notes onWestAfricanPerronawith thedescription ofanewspecies
shells in the collection of one of the MHNSMuseodeHistoriaNatural "Luis
authors (PR), it was decided to record Iglesias" Universidad, Santiago de
some additional information about this Compostela
poorlyknowngroup. MNCN Museo Nacional de Ciencias
Naturales,Madrid
Abbreviations: MNHN Muséum national d'Histoire
naturelle,París
AMNH American Museum of Natural ZMUCZoologiskMuseum,Copenhagen
History,NewYork USNM National Museum of Natural
ANSP Academy of Natural Sciences, History,Washington
Philadelphia ZSM Zoological Staatmuenchen
BMNH The Natural History Museum, Museum,Muenchen
London CJHcollectionofJuanHorro,Vigo
MCZMuseum ofComparative Zoology, CPR collection of Peter Ryall, Maria
Harvarduniversity Rain
SYSTEMATICPART
FamilyClavatulidae Gray, 1853
Genus Perrona Schumacher, 1817
Type species: Perrona tritonium Schumacher, 1817 = Murexperron Gmelin, 1791 = Pleurotoma
perroniiReeve,1843.
Perronaperron (Gmelin, 1791) (Figs. 1-13)
DerPerronMartiniandChemnitz,1788:278,pl.164.figs.1573,1574(Fig. 1).
MurexperronGmelin,1971:3559.
PerronatritoniumSchumacher,1817:218.
PleurotomaperroniiReeve,1843:pl. 11,sp.94(Fig.2).
Typematerial:FiguredsyntypeofDerPerron,whereaboutspresentlyunknown;thisspecimenis
reportedasexaminedbyStrebel(1912)butcouldnotbetracedbyKnudsen (1952)whonever-
thelessmentionsanothershelllabelledinthehandwritingofChemnitz.Pleurotomaperronii:holo-
BMNH
type 1900.2.8.26.
Othermaterialexamined:8shells(Figs.4-10),PointeNoire,Congo(CPR).
Typelocality:ErroneousforDerPerron(inOcéanoaustrali).Notmentionedintheoriginaldescrip-
tionofanyoftheothertaxa.HeredesignatedatPointeNoire,Congo.
Description: Shell (Figs. 3-12) see the more globose. Between them small
original descriptions as well as Tryon striae can be seen. In the subsequent
(1884) and Strebel (1912). The follow- whorl they detach themselves entirely
ing data can be added: the protoconch from the upper subsutural cord which
(Fig. 13) consists of about 2 1¡i shiny, also increases in prominence. In the
smooth whorls, honeybrown in colour; fourth teleoconch whorl these vestiges
thefirstwhorlslightlydarkerandof750 of the axial ribs become closer and
pm diameter. From the protoconch closer to the lower suture, declining in
whorls a series ofopisthocline axial ribs prominence until they entirely disap-
startto form, first as thin riblets extend- pear. The following whorls are smooth
ing from the top to the bottom of the with an irregular, raised subsutural
whorl, becoming stronger and shaped collarand thewhorlsaretraversedbys-
as an inverted C in the second teleo- shaped striae. At the same time as the
conch whorl where their bases become axial riblets form in the third whorl.
7
Iberus, 26 (1), 2008
about9 radial striae also start to emerge Distribution This species inhabitsthe
:
becoming slightly stronger in the fol- WestAfricaninfralittoralcoastfromCap
lowing whorls but then decreasing in Esterias (Gabon) to Ambriz (northern
intensity in the fourth or fifth whorls Angola).
andthereafterarehardlynoticeable. Special remarks: The type locality is
The shell is a light honey-brown always related with a holotype or a lec-
throughout. On the fourth whorl the totype. In the present case, the original
subsuturalcolarstarts tobecomelighter, figures are sufficient to determine the
being entirely white in the fifth whorl. identity of the species and it is not nec-
In subsequentwhorls it canbe interrup- essary to designate a neotype; Pleuro-
ted by patches of light brown; in the toma perroniiwas described lacking type
final whorl the two major cords are locality as confirmedby the label ofthis
white interspaced with small brown holotype in BMNH. If the type locality
patches the same colour as the whorl of the first description is erroneous, and
itself and the cords on the columnella no other is mentioned in the description
arealsowhite. of the synonymized taxa, it is necessary
Size the shell can reach up to 37.2 to give more detailed information.
mm :
(Bernard, 1984). Pointe Noire (Congo) is designated as
Remarks The comparison ofjuvenile the type locality being in the center of
:
specimens of P. perron with species of the knowndistributionarea, aswellas a
thegenus Clavatula (type species: Clavat- locality mentioned by Strebel (1912)
ula coronata Lamarck, 1801) show much and the source of our specimens. Our
similarity in the aspect of the opistho- material agrees very well with the
cline axial ribs, which tend to disappear figuresandtheknownholotype.
with maturityin the subsequentwhorls. Concerning the correct spelling for
For this reason itis concluded that there the ñame of this species, it must be
is a stronger relationship between these perron,whichisthefirstñameemployed
two genera, than with other genera by Gmelin (1791) and which is appa-
withinthisfamily. rently añamenotdedicated to aperson.
WhilstsomeauthorssynonymizedP. Tryon (1884) stated that Chemnitz
perron with P spirata Lamarck, 1816 it employed the common Dutch ñame
must be noted that not only are they "perron" (= flight of stairs, in reference
morphologically different, but the latter to the profile) and that Reeve (1843),
inhabits an area further to the south, misinterpritingChemnitz'sñame tobea
being restricted to the Luanda area personal ñame, Latinized it to read
whereithasbeenfoundat-5/50meters. "perronii”.
Perrona micro spec. nov. (Figs. 14-19, 21, 23, 24-28)
MNCN
Material examined: Holotype (Figs. 14, 15),in (15.05/47050). Paratypesinthefollowing
MNHN BMNH AMNH USNM ZSM ANSP MCZ
collections: (1,Fig.16); (1,Fig.17); (1); (1); (1); (1);
(1);CPR(11);CJH(6);MHNS(16,Fig. 18).
Typelocality:Palmeirinhas,southofLuanda,Angola,between3and20metersdepth.
Etymology:Thespecificñamereferstothesmallsizeofthespecies.
Description: Shell (Figs. 14-18) small six in the subsequent whorl; the two
for the genus, very solid, lanceolate. cords immediately below the suture as
Protoconch (Figs. 21, 23, 24-26) with a well as the lowest cord are more promi-
little more than one whorl, of530 pm in nent. This gives the middle part of the
diameter and white in colour. The teleo- whorl a concave appearance whilst the
conch begins with three grooves that upper and lower parts protrude before
sepárate 4 cords, later increasing to four their separation at the suture. There is
and then five spiral grooves; there are no axial sculpture except for growth
8
RoláNETAL.: Notes onWestAfricanPerronawith thedescription ofanewspecies
Figures 1-13. Perronaperron. 1: figure from MARTINI AND CHEMNITZ (1788); 2: figure ofthe
holotypeofPleurotomaperroniifromReeve (1843); 3: holotype (seebelowFigs. 11, 12) ofPleuro-
tomaperronii (BMNH) at the same comparative size; 4-6: shell (27.6 mm), Pointe Noire, Congo
(CPR); 7: shell, 28.6 mm, Pointe Noire (CPR); 8, 9: juveniles, 18.6 and 14.2 mm, Pointe Noire
(CPR); 10: shell,27.2mm, PointeNoire (CPR); 11, 12: holotypeofP.perronii 25 mm (BMNH);
,
13:spireandprotoconch,PointeNoire (CPR).
Figuras1-13.Perronaperron. 1:figuradeMARTINIYCHEMNITZ(1788);2:figuradelholotipodePleurotoma
perronii,deReeve(1843);3:holotype(véaseabajoFigs. 11, 12)dePleurotomaperronii(BMNH)conelmismo
tamañorelativo;4-6:concha,27,6mm,PointeNoire, Congo(CPR);7:concha,28,6mm,PointeNoire(CPR);
8,9:juveniles, 18,6y14,2mm,PointeNoire(CPR);10:concha,27,2mm,PointeNoire(CPR);11, 12:holotipo
deP.perronii,25mm(BMNH);13:spireandprotoconch,PointeNoire(CPR).
9
Iberus, 26 (1), 2008
Figures 14-19. Perrona micro spec. nov. 14, 15: holotype, 10.3 mm (MNCN); 16: paratype, 10.6
mm (MNHN); 17: paratype, 8.5 mm (BMNH); 18: paratype, 7.6 mm (scanningelectrón micro-
scope) (MHNS); 19: operculum (SEM). Figures 20-23. Comparison ofthe spire and protoconch
ofClavatulaquinteni(Figs. 20, 22) andPerronamicro(Figs. 21, 23).
Figuras 14-19. Perronamicrospec. nov. 14, 15:holotipo, 10,3mm (MNCN); 16:paratipo, 10,6mm
(MNHN); 17:paratipo, 8,5mm (BMNH); 18:paratipo, 7,6mm (microscopioelectrónicodebarrido)
(MHNS); 19: opérenlo (MEB). Figuras20-23. Comparación dela espirayprotoconchadeClavatula
quinteni (Figs. 20, 22)yPerronamicro (Figs. 21, 23).
10
ROLÁNETAL.: NotesonWestAfricanPerronawith thedescription ofanewspecies
Figures 24-27. Perrona micro. 24: detail ofthe spire; 25, 26: detail ofthe protoconch; 27: radular
tooth; 28: radula. Figures 29-33. Perrona obesa. 29: holotype, 34.0 mm (BMNH); 30: shell, 31.2
mm, 10 m, Namibe, Angola (CER); 31: shell, 35.7 mm, Namibe, Angola (CPR); 32, 33: shells,
40.2,41.6mm, Sacomar, Namibe,Angola(CPR).
Figuras24-27. Perronamicro. 24:detalledelaespira;25, 26:detalledelaprotoconcha;27:dientesde
la rádula;28: rádula. Figuras29-33. Perrona obesa. 29: holotipo, 34.0 mm (BMNH);30: concha,
31,2 mm, 10 m, Namibe, Angola (CER); 31: concha, 35,7mm, Namibe, Angola (CPR); 32, 33:
conchas, 40.2, 41.6mm, Sacomar, Namibe,Angola(CPR).
Iberus, 26 (1), 2008
lines which form an U-shape in the 1942, Tomopleura Casey, 1904, and Viridi-
concave central portion; this is reversed turris Powell, 1964. In all cases opercu-
onboththeupperand lowerprotruding lumandraduladonotagree.
parts forming an overall S-shape on the Perrona micro spec. nov., in spite of
whorl. There are about 6 whorls on the its small size, belongs to Clavatulidae.
teleoconch, increasing gradually in This is confirmed by the operculum
width and height. The last whorl with a medium-lateral nucleus and the
becomes elongated towards the base, wishbone-like marginal teeth with a
the siphonal canal is widely open and vestigialrachidianoneinthemiddle.
almost similar in length to the lowest Powell (1966) reviewed the Turri-
part of outer lip. The aperture is ovoid, dae (s. 1.) and defined the subfamily
withanU-shapesinusintheupperpart, Clavatulinae H. and A. Adams, 1858
a sharp external lip, and a small callus with four recent and two fossil genera;
on the columella. There are 20 spiral the recent genera being Clionella, Clavat-
grooves from the periphery to the base. ula, Perrona (with subgenus Tomellana)
The colour is typically light brown or and Pusionella. Kilburn (1985), who
orangish, with white and dark blotches dealt only with South African species,
alternating on the subsutural cords, but noted 4 genera; Toxiclionella, Bentho-
in a few specimens the colour is darker clionella, Clavatula and Clionella. Tucker
andthewhitepatternisabsent. (2004) considers 492 fossil and 97 recent
Soft parts: Study of a retracted speci- species in this group. Later Bouchet
men preserved in alcohol reveáis a light and Rocroi (2005) elevated Clavatuli-
coloured animal; the operculum (Fig. daetofamilystatus.
19) is ovoid with the nucleus centrally Thegenus Clavatula Lamarck, 1801 is
placed on the interior. The radula (Fig. relatively abundant along the West
28) is formed by two rows of about 70 Africa coast. Powell (1966) mentions 11
elongate and sharply pointed marginal species. Most of them, including the
teeth (Fig. 27) at the center ofwhich is a typespecies (ClavatulacoronataLamarck,
very small central tooth reduced to a 1801) are of large size. Other species
cusp. recently illustrated and/or described, as
Dimensions: Flolotype is 10.3 mm. detailed inourintroduction, arealsorel-
Thelargestparatypeis 12mm. atively large. Although Boyer and
Distribution: Only known from the Ryall (2006) noted that Knudsen (1952,
type locality, where it is probably 1956) classified other genera of Clavatul-
endemic. idae under the genus Clavatula, subse-
Discussion: There is no known quent authors seem to ignore these
species from WestAfrica with which it genera and their paramaters as estab-
canbe confused. Onlyjuvenile forms of lished by Kilburn (1985). A revisión
Clavatula quinteni Nolf and Verstraeten, could conclude that some of them
2006, which are much larger when belongtoothergenera.
adult, are similar in profile and coloura- The genus Clavatula is described by
tion; they both lack axial sculpture (see Powell (1966): "shell moderately large
comparison in Figs. 20 and 21, 22 and to large sized, 15 - 55 mm, very solid,
23) but C. quinteni has a much more buccinoid, coarsely axially and spirally
elongated siphonal canal, a largerproto- sculptured; with a tall, often coronated
conch (more than double the diameter) spire, and a trúncatebody-whorl, termi-
andlacksspiralgrooves. nated in a relatively short reflected and
There was some hesitation about the deeply notched anterior canal.... Oper-
generic assignment of this new species. culum ovate-lunatewith a medio-lateral
Comparison with morphologically nucleus. Radula consisting of a pair of
similar species in some genera was stout narrowly pointed marginal teeth
made, in particular Microdrillia Casey, of modified wishbone type, the proxi-
1903; Suavodrillia Dalí, 1918; Parecuneus mal extremity sepárate and superim-
Laseron, 1954, and Maoritomella Powell, posed upon the larger element. A small
12
RoláNETAL. Notes onWestAfricanPerronawith the description ofanewspecies
:
Figures34-37. Perronaspirata. 34-36: shellcoveredbyorganicmaterial, 31.5 mm, Luanda,Angola
(CPR); 37: operculum. Figures 38-41. Perronasubspirata. 38: shell, 31.5 mm; 39-41: shell, 32.0
mm, Namibe,Angola (CPR);42: operculum.
Figuras34-37. Perrona spirata. 34-36: concha recubiertapor materialorgánico, 31,5 mm, Luanda,
Angola (CPR);37:opérculo. Figuras38-41. Perronasubspirata. 38:concha, 31,5mm;39-41:concha,
32,0mm, Namibe,Angola(CPR);42:opérculo.
13
-
Iberus, 26 (1), 2008
butwe11 formed unicuspid central tooth and a narrow body-whorl...surface
is present also." According to Kilburn smooth, or nearly so... with a conspicu-
(1985) the mainfeatures ofClavatula are: ous narrowly carinate subsutural
deep anal sinus, realtivelylongsiphonal collar....operculum as in Clavatula...
canal,distictparietaltubercleandproto- radula witha pair ofelongatemargináis
conch that is bluntly domed with about and a narrow-based unicusp central
21/2whorls. tooth."
The species P. micro spec. nov. has The known WestAfrican species of
some shell characters of Clavatula but Perrona, all figured in the plates in the
has no axial sculpture and is smaller present work, are the following: P.
than all of them. Clavatula cossignanii perron (Gmelin, 1791) (Figs. 1-13), P.
Ardovini, 2004, the smallest Clavatuli- spirata (Lamarck, 1816) (Figs. 34-37),
dae knowninWestAfrica, is differentin both already mentioned, P. obesa
most features including the fewer (Reeve, 1843) (Figs. 29-33) and P subspi-
number of protoconch whorls and is rata (von Martens, 1903) (Figs. 38-41),
endemic toSenegal. Theholotypeis 13.2 both endemic to South Angola. Other
mm mm
but it can reach a size of 15.9 authors have placed other species in
(CPR). this genus, for example Perrona nifat
According to Powell (1966) the (Bruguiére, 1789) by Abbott and
genus Clionella Gray, 1847 differs from Dance (1986), but this generic place-
Pusionella Lamarck, 1801 by its clavi- ment is erroneous in our opinión.
form shape with tall, flat-sided spire Powell (1966) also mentions another
whorls; simple long flexuous axials ribs West African species belonging to this
without either subsutural or peripheral genus but placed in the subgenus
processes and a truncated body-whorl. Tomellana Wenz, 1843: Perrona Tomel
(
Kilburn (1985) defines Clionella with an lana) lineata Lamarck, 1816; but this
anal sinus; a slightnotch; siphonal canal shellhas a short, concave-outlined spire
short with no distinct parietal tubercle; and a deep slit-like anal sinus and does
protoconch somewhat conical, of about not resemble our species. Strebel
2 whorls, the first one rounded and (1912) referred other species to Tomel-
tilted. The genus is usually restricted to lana; they also do not correspond with
South Africa. P. micro spec. nov. lacks the species currently reviewed.
axial sculpture, its sinus is deep and Perrona micro spec. nov. is more
does not have a truncated body-whorl: similar to Perrona perron than to any
thereforeitdoesnotagreewithClionella. other type species and the new species
The new species was also ruled out is placed in this genus as being the
of the genus Pusionella Gray 1847 closest.Alsonoticedisasimilarityinthe
because many specific characters are colouration of the subsutural cord as
absent in P. micro; the flat-sided whorls; well as the S-shaped axial striae. We
the outer lip bordered by a broad, sub- find this at present the better solution
sutural, very slight sinus and the ratherthantocreateanewgenus.
smoothandpolishedsurface. Whilst the similarity noted with
Finally, the genus Perrona Schu- Clavatula quinteni should not create con-
macher, 1817 is described by Powell fusión, a result of this paper must also
(1966) as: "shell moderately large, 25 - be to assign this species to the genus
40mm,rathernarrowlyfusiform,witha Perrona although this has not been the
tall spire of rapidly increasing whorls reasonforthiswork.
ACKNOWLEDGEMENTS
The authors wish to thank the Euro- type material of Pleurotoma perronii and
pean Synthesys Program which allowed other types;Jesús Méndez ofthe Centro
one of the authors (ER) to examine the de Apoyo Científico y Tecnológico a la
14