BASTERIA, 55: 103-110, 1991 Maizaniellaiterum n. sp. from Gabon, another new species of the subgenus Spirulozania (Gastropoda Prosobranchia: Maizaniidae) A.C. van Bruggen SystematicZoologysection, LeidenUniversity, c/oNationaal Natuurhistorisch Museum, P.O. Box 9517, 2300 RA Leiden, the Netherlands Maizaniella (Spirulozania)iterum n. sp. is described fromGabon, West Africa.Thesubgenus Spirulozania now appears to encompass atleast seven species, all confined to the Central African forest belt. A revised key tothe genus is provided. Key words: Gastropoda, Prosobranchia, Maizaniidae, Maizaniella, Central Africa, Gabon. Further search in the extensive collectionsof the Museum National d'Histoire Naturelle(Paris), thistimeby Mr. Th.E.J. Ripken (Delft), has revealedtheexistence of yet anothernew species of the prosobranch landsnail genus MaizaniellaBequaert & Clench, 1936 (family Maizaniidae). Van Bruggen (1982) reviewed the genus and described anadditionalspecies in 1990(Van Bruggen, 1990: 189-194)1. Although the diversityofterrestrialprosobranchs is very limitedin Africa, itappears that the small snails encompassed in the genus Maizaniella represent more taxonomic units than originally surmised. So faronly nine species have beenclassified withMaizaniella, i.e. threesubgenera withone species each (Maizaniella s.s.,SierraLeone;Macromaizaniella, Cameroon;Pteromaizaniella, FernandoPo), and Spirulozania with six species. The shell of the last subgenus, introduced by Van Bruggen in 1982(type species Cyclophorus lilliputianus Morelet, 1873), is characterizedby small size, a prominent spiral element inthe sculpture (particularly ontheapex), and in additionalarge number ofcostulae. Regrettably few anatomical data are yet available for members of the genus Maizaniella; radula and genitalia have been described only for Maizaniella (Macromaizaniella) preussi (Von Martens, 1892)(fide Van Bruggen, 1982: 196). Abbreviationsused are 1/d for the ratio length ( =height)/major diameteras an indicationof theshape ofthe shell (here calculatedfrom micrometerreadings, so that thefigures calculatedfrom the measurements in mm will not always agree), R forthe numberofmajor ribs onthebody whorlofthe shell(Van Bruggen, 1982), and Rfvbw forthenumberofmajorribsobservedonthebody whorl in front view (Van Bruggen, 1982: 187). The authorities ofthe Paris museum kindly permitted a paratype to be retained for the Leidenmuseum. Maizaniella(Spirulozania) iterum nov. spec. (figs. 1-6) Diagnosis. A small, noticeably depressed species with not too distant, com- paratively littleraised costulae, with the spiral sculpture almost confinedto the apex 1 Attentionisdrawn toa regrettablemistake inVanBruggen (1990). Repeatedlyreference is madeto VanBruggen, 1985, which dateis also shown inthe listofliteraturecited. Thisis incorrect;thepaper in questionwas published on 15 December 1986. 104 BASTERIA, Vol. 55, No. 4-6, 1991 of the shell and a little beyond; this species has a comparatively high numberof costulae per surface unit. Description. Shell (figs. 1-5) small, corneous, markedly depressed turbinate, wider thanhigh, umbilicate,with slightly produced spire withblunt, mamillateapex, thin and fairly solid, transparent when fresh. Whorls 3-3 1/4, convex, separated by narrow, impressed sutures; apical whorls fairly prominent and somewhat inflated, remainderrapidly increasing in size. Body whorlcomparatively large, almostcircular in cross section. Aperture large and circular, peristome simple and acute, without reflection, practically freewithonly a fairlylimitedareain the upperlefttouching the body whorl,labrumnearly straight andsomewhatreceding inprofile. Umbilicuswide and deep, revealing all whorlsright up tothe apex, hardly overhung by the aperture. Whorls covered with thin, corneous, deciduous periostracum; initial part of shell (apex) smooth or weakly pitted, thereafter c. one whorl finely spirally engraved, remaining whorls with initially fairly prominent and rather distant, little raised costulae, which subsequently become noticeably less prominent towards theaperture; interstices much wider than costulae, covered withvery fine growth striae or secon- dary riblets; spiral sculpture becomesincreasingly insignificant towards the aperture, becoming obsolete on the body whorl, resulting in a sculpture that is nowhere reticulate. Operculum (fig. 6) moderately small, permitting some withdrawalinto the shell, circular, thin andcorneous, halftransparent, concentricand flattish, withabouteight whorls (the only isolated operculum availableis that of the holotype shell). Measurementsofshell: 2.0-2.4 x 3.3-3.7mm, 1/d0.59-0.64, 3-3 1/4whorls, aper- ture 1.5-1.6 x 1.5-1.6 mm, R= c. 50-60+, Rfvbw =c. 20-25 (for individual measurements see table 1). Operculum holotype 1.6x 1.6 mm. Animal unknown. Distribution. Gabon. Materialexamined. Gabon,Digaba (2°oo'S 11°15'E), De Morgan colln.(holo- type, figs. 1-5, andone paratype, Museum Nationald'Histoire Naturelle, Paris; one paratype, Nationaal Natuurhistorisch Museum56529). Derivationominis.— iterum= Latin, forthe second time, in the senseofoncemore. Sinceiterumis anadverb, it shouldbe consideredanounin apposition following Arti- cle llh(i2) ICZN. The namerefers tothe fact that once again in quick succession a new species of Maizaniellahas come to light. In thekey by Van Bruggen (1990: 194-195) the newspecies (more or less) keys out to Maizaniella(Spirulozania) erroris Van Bruggen, 1982. Below the key is adapted to include the new species, but the differences between the two taxa may here be tabulated as follows: Figs. 1-6. Maizaniella(Spirulozania)iterum n. sp., holotype,Digaba(Gabon),Muséum National d’Histoire Naturelle, Paris. Fig.6 is a front view ofthe operculum.Scales figs. 1-3: 1 mm; figs. 4-6: 100µm. The S.E.M. photographsemphasize the major ribs, which, when examined under a binocular microscope, are not as prominent as shown. S.E.M. photographs J. Goud, Nationaal Natuurhistorisch Museum. Van Bruggen: Maizaniella iterum n. sp. from Gabon 105 106 BASTERIA, Vol. 55, No. 4-6, J99J Van Bruggen:Maizaniella iterum n. sp. from Gabon 107 108 BASTERIA, Vol. 55, No. 4-6, 1991 height x maj.diam. 1/d R Rfvbw whorls aperture height x maj.diam. •3.7x2.4 mm 0.64 60+ 23 3 1/4 1.6x 1.6 mm 3.3x2.0 mm 0.59 c. 50 20 3 + 1.5x 1.5 mm 3.3 x2.0 mm 0.60 c. 56 3 1.5x 1.5 mm Table 1.Measurements oftheshellsofthetype series ofMaizaniella(Spirulozania)iterumn. sp. Theholotype has been indicated by an *. The secondand thirdspecimens may be subadult shells. M. iterum M. erroris - shell small: 2.0-2.4 x 3.3-3.7 mm, - shell larger: 2.5-3.4 x 3.9-4.9mm, whorls 3-3 1/4 whorls 3-3 1/2 - shell depressed: 1/d 0.59-0.64 - shell less depressed: 1/d 0.60-0.74 - costulae littleprominent - costulae noticeably raised - R =c. 50-60+ (Rfvbw =c. 20-25) - R =45-77 (Rfvbw =c. 15, holotype only!) This shows that the shells canbe differentiatedwith ease. The species may be sym- patric. M. erroris is known to be widely distributedin Liberia and possibly occurs in Sierra Leone and north-westernZaire as well (Van Bruggen, 1982: 192-194). Normally the costulae become gradually more distantand somewhat morepromi- nent towards the aperture of the shell. However, the body whorls of all three specimens ofM. iterum are characterized, particularly towards the end, by the riblets becoming almost obsolete, so that sometimes they cannot even be countedproperly in front view (see last specimen in table 1)and only with some considerabletrouble inapical view. This transitionis notgradual asmightbeexpected, but somewhatsud- den;in theholotype this marked change occurs afterc. 43, in the firstparatype after c. 35, andinthe second paratypeafterc. 40costulaeonthebody whorl(counted from the point of attachment ofthe aperture). It is hard to judge whether this is a local phenomenon (i.e. one restricted to the single population studied) or a taxonomic feature.Evenasuperficial examinationofthe specimens in question immediately drew attentionto this unique character, although itwas thought advisabletodelimitthenew taxon in a more traditionalway, i.e. by means ofcharacters known to be generally suitable for discriminationin this particular group. The only species known from Gabon isM. (S.) lilliputiana (Morelet, 1873); dataon its distribution(so faronly theholotype shellisknown; it is simply labelled"Gabon") are not available. M. (S.) iterum is the first properly localized species in Gabon. Mr. A.J. de Winterof Wageningen Agricultural University has recently donesome con- siderablework onthe malacofaunaofthis country, butso farthe new species has not turnedup inanyGabonmaterial, although anumberofsamples wasobtainedby siev- ing leaflitterfrom the forest floor. The typeseriesofM. (S.) iterumenteredthe MuseumNational d'HistoireNaturelle with the De Morgan collectionin 1922(Fischer-Piette, 1951: 20). JJ.M. de Morgan (1857-1924), 'Associe' ofthe museum, collected widely in the Near and Far East, particularly the Malay Peninsula, but does not seem to have visited Gabon himself Van Bruggen:Maizaniella iterumn. sp.from Gabon 109 (Germain, 1924). M. iterumn. sp. is the second species to be discovered in the Paris museum; attimesitseemsmore convenienttorestrict collecting expeditions to ancient museums rather than going to the expense of mounting proper field trips. A REVISED KEY TO THE SPECIES OF MAIZANIELLA Thefollowing key is adapted fromthat inVan Bruggen (1990: 194-195); of course, the same admonitionsasregards individual variation, adulthood, limitedbasic data, etc. apply here. 1 a Shell comparatively large (major diameterfrom 10 to 12 mm), depressed, with very large numberofribs(R =c. 75-c. 100), whichare closetogether; Cameroon - subgenus MacromaizaniellaVan Bruggen, 1982,only species M. preussi (Von Martens, 1892) b Shell small(major diameterfromless than 3toc. 7 mm), depressed to turbinate, with more limited numberof ribs (R =7-77), which are normally fairly widely distant (interstices always much wider thanribs) 2 2 a Shell without traces ofspiral sculpture, smallish (major diameter5.5-6.7 mm), R =c. 23-43; Sierra Leone subgenus Maizaniella s.s., only species ..................M. leonensis (Morelet, 1873) b Shellwith atleast tracesofspiral sculpture, small (major diameteralways under c. 5 mm), R =7-77 3 3 a Shell with few and irregular flange-like major ribs, R =7-12, turbinate globose (1/d 0.78-0.87), small (major diameter2.9-3.2 mm); FernandoPo — subgenus PteromaizaniellaVan Bruggen, 1982, only species M. poensis Van Bruggen, 1982 b Shell with many more ribs, R= 19-77, depressed turbinate (1/d 0.60-0.78), slightly larger(major diameter3.2-4.9 mm) subgenus Spirulozania Van Brug- gen, 1982 4 4 a R =c. 40 or more, shell small (major diameter 3.3-4.9 mm) 5 b R =at the very most 40, but usually less, shell slightly smaller(major diameter 3.2-4.2 mm) 7 5 a Major costulae onshell littleprominent, so that correct counting becomes dif- ficult, shell small, 2.0-2.4x3.3-3.7 mm; Gabon M. iterum n. sp. b Major costulaeonshell noticeably prominent andthereforeeasily counted, shell larger, 2.4-3.4x3.6-4.9 mm 6 6 a R =c. 40-77, but usually 50 ormore, shell 2.5-3.4x 3.9-4.9mm; PSierra Leone, Liberia, PZai're M. erroris Van Bruggen, 1982 b R =43-49, shell 2.4-3.1 x3.6-4.4mm; Angola M. machadoi Van Bruggen, 1982 7 a R =30-36,maximumdimensionsofshell2.9x 3.9mm; CentralandWest Africa, westward beyond the Dahomey Gap 8 b R =30 orless, maximumdimensionsofshell3.1 x 4.2 mm; Centraland(eastern) West Africa, not beyond the Dahomey Gap 9 8 a Shell smaller (2.1-2.5x3.2-3.7 mm), more depressed (1/d 0.63-0.68); West Africawest ofthe Dahomey Gap M. hiemalis van Bruggen, 1990 b Shell larger (2.6-2.9x3.4-3.9 mm), less depressed (1/d 0.72-0.78); Zaire M. chapini Van Bruggen, 1982 110 BASTERIA, Vol. 55, No. 4-6, 1991 9 a R =25-30, Rfvbw more than 12, ribs fairly pronounced, shell smaller (2.5- 2.9x3.2-3.9 mm), somewhat depressed (1/d 0.68-0.78); Gabon, Zaire M. lilliputiana (Morelet, 1873) b R =19-28, Rfvbw = 10-12, ribs noticeably pronounced, shell larger (2.6- 3.1 x 3.4-4.2 mm), slightly less depressed (1/d 0.72-0.77); Zaire M. lukolelensis (Bequaert & Clench, 1936) REFERENCES BRUGGEN, A. C. VAN, 1982. A revision ofthe African operculate land snail genus Maizaniella (GastropodaProsobranchia: Maizaniidae),withthe descriptionofsix new taxa. Proc. Kon. Ned. Akad. Wet. (C) 85: 179-204. ,1986. Further notes on Afrotropical prosobranch land molluscs (Gastropoda Prosobranchia: Maizaniidae, Cyclophoridae). Proc. Kon. Ned. Akad. Wet. (C) 89:357-378. , 1990.Notes onthe genusMaizaniella(GastropodaProsobranchia: Maizaniidae),withthedescription ofa new species fromWest Africa. Basteria54: 187-195. FISCHER-PIETTE, E., 1951. Les collections de mollusquesactuels du Museum National d'Histoire Naturelle (Suite). —J. Conchyl. Paris 91: 12-22. GERMAIN, L., 1924. J. de Morgan(1857-1924).Notice necrologique. Bull. Mus. Natn. Hist. Nat. Paris 30: 437-440.