Zoosyst. Evol. 86 (2) 2010, 283–293 / DOI 10.1002/zoos.201000011
The enigmatic Cleopatra broecki Putzeys, 1899 of the Congo River system in Africa – re-transfer from Potadomoides Leloup, 1953 (Caenogastropoda, Cerithioidea, Paludomidae)
Matthias Glaubrecht*
Department of Malacozoology, Museum of Natural History, Leibniz Institute for Research in Evolution and Biodiversity at the Humboldt University Berlin, Invalidenstraße 43, 10115 Berlin, Germany
Abstract
Received 6 April 2010 While the lacustrine gastropods from the great East African lakes, most notably of Accepted 31 May 2010 Lake Tanganyika, with their local endemisms and spectacular species flocks have found Published 24 September 2010 attention among both malacologists and more recently evolutionary biologists, our knowledge of gastropods of the central African rivers is still insufficient. In the course Key Words of a systematic revision of fluviatile paludomids of the genus Potadomoides Leloup, 1953, and in context with a study on the origin of the lacustrine gastropod radiation in Aruwimi River Lake Tanganyika, type and other material of the constituent taxa from several museum Basoko collections was studied. Re-investigating the type material housed in the Mus e Royal locus typicus L’Afrique Centrale in Tervuren, Belgium (MRAC), and of additional material found in lectotype the collection of the Museum of Comparative Zoology of the Harvard University in riverine speciation Cambridge, Mass. USA (MCZ), provided new geographical, conchological as well as lacustrine radiation anatomical evidence (with respect to the operculum and radula). Hitherto only known ancient lake from the original description, these new findings allow here to re-transfer C. broecki Lake Tanganyika Putzeys, 1899 from Potadomoides to Cleopatra Troschel, 1856.
Introduction
“The old river in its broad reach rested unruffled at the decline of day, after ages of good service done to the race that peopled its banks, spread out in the tranquil dignity of a waterway leading to the uttermost ends of the earth.” – Joseph Conrad, 1899: Heart of Darkness The great East African lakes, and most notably those in Lake Tanganyika has also stirred much interest among the Rift such as Lake Tanganyika and Lake Malawi, malacologist and evolutionary biologists (Glaubrecht are generally regarded as hotspots of aquatic biodiver- 2008; see also review of literature therein). sity, with local endemisms and spectacular species At the same time, though, the knowledge of fresh- flocks of various animal groups. As these lakes provide water molluscs in adjacent regions of Africa is still natural laboratories, i.e. examplary settings for studies scarce. In particular, the gastropod fauna of the central on evolutionary processes of intra-lacustrine speciation African rivers is insufficiently studied, mainly due to and adaptive radiation, their faunas have received con- continuous adversary logistical and/or political rea- siderable scientific attention (see e.g. reviews in Coul- sons. However, as has been pointed out by Glaubrecht ter 1991; Rossiter & Kawanabe 2000; Danley & Kocher & Strong (2007: 397), not only lakes such as in parti- 2001; Kocher 2004). Providing another instructive mod- cular ancient Tanganyika but also the enormous Con- el for understanding evolutionary processes, such as go River drainage provide stable evolutionary systems, speciation and radiation, the gastropod assemblage of both in their own right and with distinct inherent en-
* E-mail: [email protected]
# 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim 284 Glaubrecht, M.: Re-transfer of Cleopatra broecki vironmental dimensions. Consistent with this view is nities for speciation and radiation under various condi- the hypothesis that at least part of the fauna of Lake tions, as Glaubrecht (2004) and Glaubrecht & Strong Tanganyika might be older than the lake itself, its ba- (2007) have suggested for African paludomid gastro- sin thus potentially functioning as an evolutionary re- pods. servoir since the Miocene, as we have anticipated re- It is this context that renders the fluviatile gastropods cently for its paludomid gastropods (Glaubrecht 2004; from Central Africa of special interest. Equal to great Wilson et al. 2004). lakes such as Tanganyika and Malawi, the Congo River With emphasis starting to shift to non-lacustrine set- and its easternmost tributaries have an outstanding rich tings in studies not only of African cichlid fishes (e.g. species assemblage, not only of unique molluscs, that Kocher 2005; Joyce et al. 2005) but also of Asian and deserve more attention. Unfortunately, the material ba- African cerithioidean gastropods (e.g. Glaubrecht 2004; sis as well as our knowledge for many of the constituent Glaubrecht & K hler 2004; Glaubrecht & Strong 2007; members for long has remained regrettably poor. De- K hler & Glaubrecht 2010; K hler et al. 2010), lacus- spite them being demonstrably of considerable interest trine species flocks are not necessarily to be seen as for evolutionary biology, no large-scale exploration of evolutionary dead ends. Quite to the contrary, it can be limnic habitats in the Congo Basin has been undertaken expected that the potentially repeated switch of limnic for several decades now, and I am not aware of any taxa between riverine and lacustrine habitats during the more recent collections of relevant material from the course of their evolution guaranteed their survival, and Congo River, rendering even the oldest and poorest mu- at the same time provided ample evolutionary opportu- seum collection records of great importance.
Figure 1. The Congo River drainage in Central Africa, with the occurrences of Cleopatra broecki in its tributary, the Aruwimi River, and of species attributed to Potadomoides Leloup, 1953. Basoko, as locus typicus given for C. broecki zonata; see text for more; * = locus typicus of the type species Potadomoides pelseneeri; ~ = Potadomoides bequaerti; & = Potadomoides hirta; * = Potadomoides schoutedeni. Scale bar = 100 km.
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Among the enigmatic freshwater gastropods, for Materials and methods which we lack most biological information since their first descriptions, are species of the paludomid genera This study resulted from a revision of the constituent species of Pota- Cleopatra Troschel, 1856 and Pseudocleopatra Thiele, domoides from the Congo River system that is described in detail 1928 that occur also in the drainages of the Congo Riv- elsewhere (Glaubrecht & Strong 2007). For Cleoptara broecki the er system in the Central African Basin. To date, the type material in the Mus e Royal L’Afrique Centrale, Tervuren, Bel- systematic placement of several of their species is es- gium (MRAC) was re-studied (Fig. 2), a sample that produced an overlooked operculum (Fig. 4a), but no soft bodies. Additional materi- sentially based on shell characters alone, since opercu- al (Figs 2f and 3), that is identified by the present author as lum and radulae or other anatomical characters re- C. broecki based on comparative conchology as well as on an opercu- mained unknown. lum identical to that of the lectotype (Fig. 4), was located in the Mu- For example, in a short note the Belgian malacologist seum of Comparative Zoology, Harvard University, Cambridge, Mass., S. Putzeys (1899) described Cleopatra broecki, that la- USA (MCZ). Radulae retrieved from dried soft bodies found with the ter authors, e.g. Mandahl-Barth (1967) and Brown latter sample help to elucidate the radula morphology of C. broecki (1994: 131), transfered to the genus Potadomoides which was unknown to date (Fig. 5). For radula comparison a sample of the type species Cleopatra bulimoides, from Medinet el Fajum in Leloup, 1953, a taxon with species occurring in the Egypt from the ZMB collection (ZMB Moll. 31148-1), was studied. Lualaba and Luvua tributary of the upper Congo River Methods and terminology for shell measurements follow Glau- as well as a single species, viz. the type P.pelseneeri brecht (1996). Drawings were done using a Leica 9.5 binocular micro- Leloup, 1953, disjunctly distributed in the delta of the scope with camera lucida. Radulae were prepared from re-hydrated Malagarasi River that flows into eastern Lake Tanga- soft bodies found within the shell, and photographed using a Jeol nyika (Fig. 1). These taxa are of particular interest in 6300F Scanning Microscope at ZMB with standard procedures. For- relation to the ancestry of the radiation of the so-called mula for radular tooth descriptions are as follows. Rachidian: num- bers of denticles on the left side/median denticle(s)/numbers of denti- „thalassoid“ (i.e. marine-like) gastropod fauna of Lake cles on the right side. Lateral teeth: inner cusps/pronounced denticle/ Tanganyika. It was long assumed, according to Brown outer cusps. Marginal teeth: number of cusps on inner marginal tooth (1994: 129), that among the living gastropods Potado- þ number of cusps on outer marginal tooth. moides had the strongest claim for consideration in re- The name used throughout this paper for the former Belgian Con- lation to the ancestry of this Tanganyikan radiation. go, later known as Zaire, is Democratic Republic of Congo (DRC). While addressing the question of the origin of the Tan- ganyikan gastropod radiation (Glaubrecht 1996, 2008) and systematically revising the fluviatile Potadomoides On the taxonomic history (Glaubrecht & Strong 2007) it was established, how- of Cleopatra broecki ever, that this taxon is not ancestral to the entire ende- mic species flock of thalassoid Tanganyikan gastropods. The systematic placement of Cleopatra broecki re- Instead, it was suggested that a fluvio-lacustrine clade mained uncertain for over a century. The Belgian mala- Nassopsinae, uniting two lacustrine taxa (Lavigeria and cologist S. Putzey (1899) published a very short scienti- Vinundu) with the fluviatile Potadomoides, apparently fic note of six printed pages only, devoid of any other represents an early independent lineage of East African information and presenting basically the diagnoses for paludomids that until recent times survived in and adja- several, mostly terrestrial gastropods, for example spe- cent to Lake Tanganyika. Consequently, while Potado- cies of Cyclophorus and Streptaxis, before adding in a moides does certainly not serve as a suitable model for last brief paragraph the description of a new limnic pa- the majority of the thalassoid gastropods, it might serve ludomid species, which is depicted in his text-fig- as a model for an African paludomid with the potential ure 16. to colonize not only fluviatile but also lacustrine habi- Unfortunately, nothing is known as to who collected tats (Glaubrecht 2004, 2008). and/or brought back Putzeys’ gastropod material from In the course of an ongoing systematic revision of the Congo, which suffered at that time under King Leo- African paludomids, types and other material of consti- pold II. Since the European nations’ Berlin Congo con- tuent taxa from several museum collections were stud- ference of 1884–1885 on colonial influences in Africa, ied. In comparison with the types of Potadomoides the euphemistically so-called “Congo Free State” was and species of Cleopatra I will here investigate addi- de facto Leopold’s private colony before being turned tional type material housed in the collection of the Mu- in 1908 into the Belgian Congo until 1960 [with a re- s e Royal L’Afrique Centrale in Tervuren, Belgium, as gime of terror leading to the decimation of approxi- well as material found in the collection of the Museum mately three to ten million people from 1885 to 1910 of Comparative Zoology of the Harvard University in (see Hochschild 1998); as described e.g. in Joseph Con- Cambridge, Mass. USA. The present paper provides the rad’s (1899) famous novella “Heart of darkness”, first conchological, geographical and anatomical evidence published as three-part magazine series, coincidentally (with respect to operculum and radula), that allows re- in the same year as Putzeys’ taxa; see epitaph]. transferring one of the species, broecki, which is pre- In his revision of African freshwater snails the Ger- sently affiliated with Potadomoides and only known man malacologist Kobelt (1909: 383) listed broecki from the original description, to the paludomid Cleopa- within the genus Cleopatra, but discussed its affinity tra. also to Viviparus and Bellamya, while Pilsbry & Be-
# 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim museum-zoosyst.evol.wiley-vch.de 286 Glaubrecht, M.: Re-transfer of Cleopatra broecki quaert (1927: 296) accepted the original placement mer Congo River system to the east of Lake Tanganyi- within Cleopatra. It was later the Danish malacologist ka, viz. the Malagarasi River (Fig. 1), Mandahl-Barth Mandahl-Barth (1967) who suggested transferring this (1967) also transferred three other species from the species to Leloup’s (1953) new and, at that time, mono- upper Congo River system. These three species, viz. typic genus Potadomoides. Adding to P.pelseneeri P.bequaerti, P.hirta and P.schoutedeni, were originally Leloup, 1953, which is known to only occur in the for- described by Dautzenberg & Germain (1914) as mem-
Figure 2. Shells of Cleopatra broecki Putzeys, 1899, in comparison with other congeneric taxa and to Potadomoides. a. Cleopatra bulimoides (MRCA). b. Potadomoides pelseneeri, paratypes (IRSNB no. 145). c. Lectotype of Cleopatra broecki (MRAC 47360, Aruwimi River, ded. Putzeys). d. Paralectotype of Cleopatra broecki (MRAC 47361, Aruwimi River, ded. Putzeys); e. Holotype of Cleopatra broecki zonata (MRAC 47362, Aruwimi River, ded. Putzeys). f. Cleopatra broecki (MCZ 171520, Luozi, Kibunzi, Con- go; coll. W. Wanson; acc. no. 1027). Scale: 5 mm.
museum-zoosyst.evol.wiley-vch.de # 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim Zoosyst. Evol. 86 (2) 2010, 283–293 287 bers of the widespread African genus Cleopatra. How- is flattened and mostly evenly rounded. Shell colour is ever, all three of them actually exhibit radula features mostly beige to brown, sometimes dark brown; in some very similar to Leloup’s P.pelseneeri. Mandahl-Barth species with several smaller spiral bands. The opercu- (1967) examined (and in one case depicted) the radula lum is thin, concentric, with spiral, slightly eccentric of these three new Potadomoides species, which were nucleus, concave and of mostly dark horny colour. recently re-discovered and studied by Glaubrecht & Some 17 species are known from Africa and Madagas- Strong (2007). However, in case of broecki, Mandahl- car; a modern revision is lacking but desperately Barth neither figured nor described the radula. needed. For more details see e.g. Mandahl-Barth According to him, Putzeys’ original description, al- (1967), Brown (1994) and Glaubrecht (1996). beit being rather brief, “indicates a Potadomoides rather than a Cleopatra” (Mandahl-Barth 1967: 130). Himself being brief there (with only five lines on this Cleopatra broecki Putzeys, 1899 taxon), he did not further specify as to why this should be the case. However, Mandahl-Barth added, “a final Cleopatra broecki Putzeys, 1899, Annales de la Soci t Royale Mala- decision must be postponed until the radula is known”. cologique de Belgique, Bulletins des S ances 34: 60, fig. 16. Cleopatra broecki zonata (as var. zonata) Putzeys, 1899, Annales de Later, Brown (1994: 130–131, fig. 62d) has redrawn la Soci t Royale Malacologique de Belgique, Bulletins des the original shell figure (apparently without studying S ances 34: 60. the types), and also allocated broecki within Potado- Cleopatra broecki – Kobelt, 1909, in Martini, F. H. & Chemnitz, J. H. moides, albeit “with hesitation only”, since radula and (eds), Systematisches Conchylien Cabinet, n.F., vol. 2 (21a): 398, operculum were unknown. This species since then re- pl. 76, fig. 18. ceived no further attention or study. It was, however, Cleopatra broecki – Pilsbry & Bequaert, 1927, The aquatic mollusks explicitly excluded from their study on Potadomoides of the Belgian Congo: 296. Potadomoides (?) broecki – Mandahl-Barth, 1967, Revue de Zoologie by Glaubrecht & Strong (2007: 393), for the reason of et de Botanique Africaines 76 (1–2): 130. new data being available, which is presented here. (?) Potadomoides broecki – Brown 1980 [1994], Freshwater snails of Africa: 114, fig. 64d [p. 130, fig. 62d]. Type locality.“Trouv sur des valves d’Aeth ries de la rivi re Aruwi- Systematic Part mi, affluent du Congo”; Aruwimi River, today DR Congo, Oriental Province (Fig. 1). Although not given more precisely by Putzeys Paludomidae (1899) in his original description, and hitherto overlooked, it is never- theless possible to restrict the type locality to Basoko according to Cleopatra Troschel, 1856 the label associated with the holotype of Putzeys’ var. zonata, for which he stated in the text that the habitat is “meme provenance” (as This genus of paludomid Cerithioidean (for a discus- that of the nominal broecki). This doubtlessly refers to the larger vil- sion of the familial affiliation see Glaubrecht 2008), is lage or today’s city of the same name, located at the eastern shore of characterized by mostly ovate, medium-sized shells the Congo River, just north of where the Aruwimi enters. with generally more or less sharply pointed, but often Type material. C. broecki: Lectotype, by present designation (MRAC eroded (or decollated) spire with up to six whorls, that 47.360; from Aruwimi River, ded. Putzeys 1935); this shell (Fig. 2c) are mostly rounded in cross-section and usually have a agrees best with Putzeys’ original text-figure and the shell measure- distinct shoulder. The whorls are generally smooth, ments given. One paralectotype (MRAC 47.361; Aruwimi River, ded. Putzeys 1935) (Fig. 2d). Holotype of zonata (MRAC 47.362) from the sometimes slightly angulated, with a sculpture consist- same series and with the location “Basoko” stated on the label ing essentially of growth lines only; however, some spe- (Fig. 2e). cies also exhibit spiral elements, such as keels or Additional material examined. Here attributed to Cleopatra broecki: ridges; often these are not very pronounced. The aper- A series of n = 13 specimens (MCZ 171520), from “near Luozi, Ki- ture is usually higher than wide, angular above and bunzi, Zaire [= Congo]; coll. W. Wanson; acc. no. 1027” (see Fig. 2f). rounded or slightly produced below. The outer margin The location lies at the northern bank of the lower Congo River, north
Figure 3. Shells of Cleopatra broecki, MCZ 294126; from 3 km E of Inga, N of Matadi, lower Congo River mainstream, E bank of river; from fish stomach, coll. T. Roberts, D. Stewart, 1 Aug 1973. Scale: 1 cm.
# 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim museum-zoosyst.evol.wiley-vch.de 288 Glaubrecht, M.: Re-transfer of Cleopatra broecki of Matadi. Also attributed here to C. broecki a smaller series of n = 4 Description. specimens (MCZ 294126), also from lower Congo River, N of Mata- Shell (Fig. 2). Shells are smooth and thick; the only di: “3 km E of Inga, Zaire [= Congo] River mainstream (E bank of sculptural element is a faint anwachsstreifung. The river) (5 27.5 S, 13 36 E), from fish stomach; coll. T. Roberts, D. shells have a weakly angular periphery, with short Stewart, 1 Aug 1973” (Fig. 3). transverse ridges on upper whorls. The lectotype Taxonomic remarks. Although not directly indicated in (MRAC 47.360), as designated herein (Fig. 2c), was his note, Putzeys (1899) apparently named this species originally stated to measure 10.5 6.5 mm, with a after the then active and known Belgian malacologist 6 mm long aperture (Putzeys 1899). The syntype series Ernest van den Broeck. He described it based on a comprised n ¼ 3 shells with the following parameters: small series of only three shells, as can be judged from height ¼ 9.23 (sd 1.01) and width ¼ 6.90 (sd 0.70). The the types that came to the MRAC in 1935, according to height to width ratio is here calculated as h/w ¼ 74.99 the cryptic label information. In his report Putzeys dif- (sd 6.01). Shell measurements are given in Table 1; ferentiated, next to two larger shells (Figs 2c–d) also compare also Figure 6. one variety zonata for a slightly smaller, banded shell. The shell measurements for the additional material The latter was already considered by Pilsbry & Be- from the MCZ series (Figs 2f and 3) are also given in quaert (1927) to be conspecific, which is agreed on Table 1. For the n ¼ 13 shells (MCZ 171520) the param- here from the comparison of the respective types (see eters are quite similar to the type series: height ¼ 8.5 Fig. 2e). For the full taxonomic history of the changing (sd 1.08), width ¼ 6.8 (sd 0.93), although with a higher generic affiliation of broecki see above. h/r ratio ¼ 81.06 (sd 5.60) and 85.8 (sd 6.67), respec-
Table 1. Shell parameters of the types of Cleopatra broecki, and additional material attributed in the present paper to this taxon from the MCZ collection. Note that the apex of all shells is decollated. Measurements given in mm; x = arithmetric mean, sd = standard deviation.
Paludomidae repository height width whorls
Cleopatra broecki MRAC 47.360 lectotype 10.1 6.9 3 MRAC 47.361 paralectotype 9.5 7.6 2 MRAC 47.362 type 8.1 6.2 3 x: 9.2 6.9 sd: 1.01 0.70
height width whorls
Cleopatra broecki MCZ 171520, n ¼ 13 9.0 7.3 2 6.9 5.7 3 9.4 7.9 2 10.6 8.1 2 9.4 7.9 2 9.6 7.7 2 8.2 6.6 2 8.8 7.1 2 7.8 6.3 2 7.2 6.9 2 7.4 5.7 3 7.3 5.2 3 8.3 6.6 2 x: 8.5 6.8 sd: 1.08 0.93
height width whorls
Cleopatra broecki MCZ 294126, n ¼ 48.97.14 9.8 9.0 3 10.4 9.5 2 10.6 8.5 2 x: 9.9 8.5 sd: 0.76 1.03
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Figure 4. Operculum of Cleopatra broecki in comparison with the type species. a. Cleopatra broecki, lectotype (MRAC 47360); b. Cleopatra broecki (MCZ 171520); c. Cleopatra bulimoides (MRCA). Scale: 1 mm tively, as it is the case of the second, smaller series cies of the latter genus exhibit a narrow rachidian tooth, (MCZ 294126). slightly more than 1.5-fold larger than wide, tapering to a V-shaped base, and with only few, mostly three cusps Operculum (Fig. 4). Among the shells of the original of the 1/1/1 pattern only, the central tooth in Cleopatra, syntype series one detached operculum was found, here shown for Cleopatra bulimoides (ZMB Moll. which is attributed to the lectotype of C. broecki 31148-1, from Medinet el Fajum) (Figs 5a–c) and that (MRAC 47.360), due to size and fit with the aperture found in C. broecki (Figs 5d–f), appears to be different of this particular shell. As typical for Cleopatra,itis in essential features. concentric and with a spiral nucleus. Only the nucleus, The rachidian of C. broecki is of roughly squarish to positioned slightly eccentic with respect to the columel- rounded shape, nearly as wide as high, with up to 15 lar side, is paucispiral, lamellar, and of less than half denticles (7/1/7) at the upper edge (Figs 5a–b). This is the length of the operculum (Fig. 4a). The same pattern also found in C. bulimoides (Figs 5d–e) as well as other was found in one operculum of Cleopatra broecki from Cleopatra species; for C. ferruginea see also Glau- the additional series (MCZ 171520) from Kibunzi brecht (1996) and radula figures in Pilsbry & Bequaert (Fig. 4b). Here the nucleus is deeply concave with (1927: 289). Lateral teeth in C. broecki (Fig. 5d) again knob-like intrusions on the ventral side. Again, when bearing many small denticles, mostly of a 2–3/1/9 þ compared to the operculum of the type species Cleopa- pattern, of roughly triangular shape; with the central tra bulimoides (MRCA), we find this to be also con- denticle pronounced, larger and bluntly rounded, and centric, with eccentric and spiral, lamellar nucleus, of the outer flanking denticles decreasing in size to con- less than half the entire length (Fig. 4c). tinue in the relatively short lateral extensions. Inner and Anatomy. The animal is unknown, as no soft bodies outer marginal teeth moderate long, both with a row of were found with the original type series. The radulae up to 18 or 20 very small denticles. described below originate from dried soft bodies found In the n ¼ 2 radulae studied for the C. broecki material and extracted from the additional shells in the MCZ the ribbon consists of between 60 to 82 rows, as compared (171520), here attributed to C. broecki based on shell to about 60 rows in n ¼ 2 radulae in C. bulimoides (this parameters and operculum. The only features visible in study) and 70, 76 and 82 rows, respectively, found in Pota- the dried-up animals were the black colour of body, domoides species (Glaubrecht & Strong 2007). with a pigmented, whitish stripe along the right side running to the propodium. Apparently, they lack a Distribution and Ecology. Reported originally only clearly invaginated genital gutter or any other features from the Aruwimi River, a tributary of the River Con- related to reproductive organs in this place, but have a go, northwest of Kisangani (Fig. 1). However, nothing smooth mantle edge without papillae. more is known as to the precise occurrences of this tax- on along this river that originates far to the east, in the Radula (Fig. 5). The radulae found in shells attributed mountainous region of the eastern shoulders of the Rift here to Cleopatra broecki (MCZ 171520, from Kibunzi) Valley, close to Lake Albert, at the border of the DR is clearly distinct, in particular with respect to the ra- Congo and Uganda. I searched, albeit in vain, for those chidian and laterals, from that known in all radulae of locations that Putzeys (1899) gave for the terrestrial Potadomoides; for comparison and description see snails also described in his short paper (e.g. Many ma, Glaubrecht & Strong (2007). While all known four spe- foret de Micici, foret de Waregga, and Nseudw etc.).
# 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim museum-zoosyst.evol.wiley-vch.de 290 Glaubrecht, M.: Re-transfer of Cleopatra broecki
Figure 5. Radulae of Cleopatra broecki, in comparison with congeneric taxa. a–c. Cleopatra bulimoides, Medinet el Fajum (ZMB Moll. 31148–1). d–f. Cleopatra broecki from Congo River, Kibunzi (MCZ 171520). Scale: 10 mm.
Based on the inclusion of additional material attribut- Lamarck, 1807 (the “Nile or Congo Oyster”), within ed here to Cleopatra broecki based on the evidence pre- the Etheriidae Deshayes, 1830. As an edible clam it is sented above, the distributional range of the species ex- harvested by local people along African rivers as tradi- pands further downstream along the Congo River, to tional food. include also its lower reaches N of Matadi, with two locations known now at Inga, on the E bank of the Congo River mainstream, and at Luozi near Kibunzi, at the northern bank of the lower Congo. However, as de- Discussion tailed above, the type locality should be restricted to Basoko, immediately at the confluence of the Aruwimi As is evident from the continuous confusion of species with the Congo River. of Cleopatra and Potadomoides in earlier accounts (see According to a note in Putzeys (1899: 60), broecki historical review above), the shells of those taxa in was found there on the shells of Etheria. It is an oys- question here are quite similar to each other. However, ter-like, sessil freshwater bivalve of equatorial Africa, re-investigation of the types of C. broecki and the com- with today recognized a single species, Etheria elliptica parison of now available data on shell, operculum, ra-
museum-zoosyst.evol.wiley-vch.de # 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim Zoosyst. Evol. 86 (2) 2010, 283–293 291 dula and geographical occurrence allows to differentiate freshwater Cerithioidea (Glaubrecht 1996, 1999, 2006, between both genera and to re-transfer this species. 2008). Thus, next to the operculum that allows to now link the relevant sample MCZ 171520 to the MRAC Characters used in systematic placement types of broecki, the most conclusive evidence for re- The overall shell shape of relevant paludomids from the transfering this species to Cleopatra comes from its ra- Congo River drainage, given as shell height versus dula features. The radula in Potadomoides reveals a ser- shell width, reveals that not only Potadomoides species ies of tooth and denticle features that clearly distin- (including the type pelseneeri) but also other Cleopatra guish it from that in Cleopatra (see e.g. Brown 1994; species (including the type bulimoides) can be differen- Glaubrecht 1996; Glaubrecht & Strong 2007). Among tiated from C. broecki. In the compilation of the data for this, most importantly the rachidian, lateral and margin- Figure 6 I have used the height and width parameters als of the Cleopatra species studied so far are all of for these taxa to show the occupation of different mor- different shape, and they all bear regularly far more phospace in three Potadomoides and four Cleopatra cusps than found in the four Potadomoides species. The species, with C. broecki being distinguishable from all, narrow, tall rachidian in the latter is clearly distinct but closest to the type C. bulimoides. In contrast to the from the squarish to round and much wider central latter two relatively small-shelled species, C. johnstoni tooth in Cleopatra including broecki, as is the often and in particular C. ferruginea clearly stand out as taxa spatula-like broad central denticles of the rachidian and with larger shells. lateral. Most strikingly, however, in all Potadomoides The data presented here for the operculum of the lec- species, we found the outer and inner marginal teeth to totype of C. broecki for the first time clearly reveals a be dissimilar, with the inner ones with major cups concentric one with paucispiral, slightly eccentric nu- being very broad and spatula-shaped (Glaubrecht & cleus, as it is also found in Cleopatra and Pseudocleo- Strong 2007: fig. 6), whereas in all Cleopatra species patra (see Glaubrecht 1996). With this the species is to known so far the denticles of the marginals are much be distinguished from Potadomoides, where the opercu- more numerous and of similar size and shape in the in- lum was found to be paucispiral with sub-central nu- ner and outer ones. cleus on the columellar side (see Glaubrecht & Strong Therefore, based on the similarity of their radulae 2007: 374, fig. 5). with the type species pelseneeri, Mandahl-Barth (1967) Radula features have been proven to be of great sys- correctly assigned and transferred Dautzenberg & Ger- tematic value not only in many gastropod taxa in gen- main’s (1914) former Cleopatra species bequaerti, hirta eral, but in particular among the different lineages of and schoutedeni to Leloup’s (1954) Potadomoides.
Figure 6. Shell shape of paludomids from the Congo River drainage, here given as shell height vs. shell width, showing the occupation of different morphospace by three Potadomoides and four Cleopatra species, respectively; including the type species P.pelseneeri and C. bulimoides in comparison with Cleopatra broecki.
# 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim museum-zoosyst.evol.wiley-vch.de 292 Glaubrecht, M.: Re-transfer of Cleopatra broecki
Lacking this particular piece of evidence, though, he been suggested earlier as key innovation for lacustrine was only wrong in the case of Cleopatra broecki. colonization, speciation and radiation; for critical dis- cussion and literature see Glaubrecht (2008). On the occurrence and distribution of Cleopatra Hopefully, in the future new data will come to light broecki for congeneric taxa of Cleopatra, as their occurrence to Glaubrecht & Strong (2007) have reconstructed and the west and north of the Tanganyikan basin and drai- commented on the compelling disjunct distribution of nage might eventually help to better understand the ori- Potadomoides, with P.pelseneeri being restricted to the gin of the lacustrine malacofauna of this ancient lake. delta region of the Malagarasi River east of Lake Tan- In contrast to the long held assumption of an in situ ganyika, whereas the three congeneric species P.be- radiation of its “thalassoid” species flock, Lake Tanga- quaerti, P.hirta, and P.schoutedeni inhabit the Congo nyika has possibly functioned as a reservoir for ancient River with its tributaries Lualaba and Luvua (but appar- African lineages, implying that the now lacustrine taxa ently not the Lukuga), west of the Tanganyikan Rift originated elsewhere (in the west). As long, however, as (see Fig. 1). Thus, concerning the distribution as recon- the fluviatile gastropod fauna of adjacent river systems structed here and the restricted type locality of Cleopa- in Central and East Africa is not better known, even- tra broecki at the confluence of the Aruwimi with the tually founded on new collections of relevant material Congo River, the occurrence in the Oriental Province especially from the Congo River drainage, even the of the DRC seems to be sufficiently separate from that oldest and poorest museum collection records – such of the remaining Potadomoides species. as in case here of Putzeys’ broecki – remain important However, given our poor state of knowledge on the in context of reconstructing the evolutionary history of fluviatile malacofauna in the eastern Congo River sys- riverine and lacustrine gastropod radiations in Africa. tem, the possibility can, of course, not be excluded that the actual distributional range of both taxa is larger, rendering their occurrence less disjunct, parapatric or Acknowledgments maybe even sympatric. Nevertheless, in concert with the morphological data provided herein, the biogeogra- I am grateful to F. Puylaert (MRAC) and Adam Baldinger (MCZ) for loan of the material, and to the latter also for his help during my visit phical facts known to date lend additional support to several years ago. An Ernst Mayr Research Grant offered by the Har- the removal of broecki from Potadomoides and its as- vard University to visit the MCZ collection in December 1998 is still signment to Cleopatra. In contrast to the restricted thankfully acknowledged. I also thank Helena Franke (ZMB) for tech- range of the former, congeneric species of Cleopatra nical assistance and for help with preparing the figures. I am indebted seems to occur widely distributed from west to east to Michael Ohl and Frank K hler for their constructive comments on across central Africa, and reaching all the way from the an earlier version which helped to improve the manuscript. Additional north through the extensive Nile drainage system to the financial support was provided through grant Gl 297/5-1 of the Deutsche Forschungsgemeinschaft. southern parts of Africa, expanding even to the island of Madagascar (see Brown 1994). References
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