AÇOREANA, 2011, Suplemento 7: 209-228

WHEN THE GALÁPAGOS “FINCHES” ARE AZOREAN SNAILS

António M. de Frias Martins

CIBIO-Açores, Centre for Research in Biodiversity and Genetic Resources, Department of Biology, University of the , 9501-801 Ponta Delgada, São Miguel, Azores, e-mail: [email protected]

ABSTRACT On his way home, towards the end of the historic voyage of H.M.S. Beagle, Charles Darwin stopped by the Azores. He subsequently wrote a detailed report on the people and their life style, but had nothing to say about the archipelago’s fauna and flora, except that everything reminded him of England. Yet, if Darwin was to return now, he would find evidence of evolution, mostly in the terrestrial molluscs. Of the 101 described of land and fresh- water molluscs in the Azores (halophilic species excluded), 47 are endemic, and there is strong evidence for 28 additional species, not yet described. This wealth of endemism is distributed throughout the nine islands of the archipelago in patterns closely related to the age and the volcanic activity of each one. Examples are given of distributional patterns of endemic taxa, namely of the and Enidae. Reference is made to the on-going research testing the speciation patterns seen in Drouetia in relation to the theory of punctuated equilibrium, as well as to the variability of Napaeus pruninus and reticulate evolution.

RESUMO A caminho de casa, mesmo no fim da histórica viagem do Beagle, Darwin parou nos Açores. Escreveu um relatório pormenorizado sobre as gentes e sua maneira de viver, mas nada teve a dizer sobre a fauna e a flora local, excepto que lhe lembravam a sua velha Inglaterra. No entanto, se Darwin voltasse agora, poderia muito bem encontrar evidência de evolução, sobretudo nos moluscos terrestres. Das 101 espécies de moluscos terrestres e de água-doce descritas (exceptuando-se as espécies halófilas), 47 são endémicas, e há evidência forte para 28 espécies adicionais, ainda não descritas. Esta riqueza de endemismos distribui-se pelas nove ilhas em padrões

PPaginação_21.inddaginação_21.indd 209209 119-01-20129-01-2012 11:52:0511:52:05 210AÇOREANA 2011, Suplemento 7: 209-228

estreitamente relacionados com a idade e a actividade vulcânica de cada ilha. São dados exemplos de padrões de distribuição de taxa endémicos, nomeadamente dos Oxychilidae e dos Enidae. Faz-se referência à investigação em curso associando os padrões de especiação em Drouetia e a teoria do equilíbrio pontuado, bem como a variabilidade de Napaeus pruninus e a evolução reticulada.

OCEANIC ISLANDS AND did not bring any revelation of ENDEMISM: THE EXAMPLE striking endemism; instead, it OF THE AZOREAN reminded him of England: MALACOFAUNA “The rocks are covered in some parts by a thick brushwood about volution has been histori- three feet high, and in others by Ecally linked to islands, not heath, fern, and short pasture: because they are the only places a few broken down old stone where it happens but because walls completed the resemblance they are more or less contained with the mountains of Wales. I environments, suitable for in- saw, moreover, some old English depth studies. They are test friends amongst the insects; and tubes of evolution. Darwin of birds, the starling, water- (1859: 105) thought so when wagtail, chaffi nch, and blackbird.” searching for answers to unravel (Darwin, 1839: 369). the origin of species: The evidence missed by “If we turn to nature to Darwin – the land snails – was test the truth of these remarks, hiding beneath the fallen leafs of and look at any small isolated the remnants of the laurisilva. area, such as an oceanic island, The Azorean malacofauna, although the number of species contrary to that of Madeira, was inhabiting it is small, […] yet unknown at the time Darwin of these species a very large sailed aboard the Beagle. The proportion are endemic, - that is, first Azorean endemic mollusc, have been produced there, and Bulimus [=Napaeus] pruninus, nowhere else in the world.” was described by Augustus A. Yet, when Darwin landed on Gould in 1848. It was only in the Azores twenty three years 1860 that Arthur Morelet pro- previously, the fauna and flora he duced the first extensive work had an opportunity to examine on the Azorean land snails. Of

PPaginação_21.inddaginação_21.indd 210210 119-01-20129-01-2012 11:52:0611:52:06 MARTINS: WHEN THE “FINCHES” ARE SNAILS 211

the 69 species recorded, 32 were supratidal prosobranchs exclud- considered endemic. Backhuys ed), the count will be about 129 (1975) compiled the second ma- species of which 75 are endemic, jor list of the Azorean terres- thus raising the percentage en- trial malacofauna and, though demism to ~58%. If introduced raising the count to 99 species, species are excluded (those of which 39 were endemic, he thought to have arrived after the clearly stated: 15th century, the beginning of the “The present paper does not islands’ human colonization), mark the end of the road, but then the percentage of endemics rather it marks the starting would rise to ~79%, thus provid- point for further research. Many ing a more realistic scenario for problems remain to be solved the pattern of evolu- and many new and interesting tion expressed in the islands. facts will be discovered in the A closer look at Figure 1 re- future” (p. 5). veals various biogeographic pat- The last count based on pub- terns and one peculiar situation. lished records and preliminary The terrestrial mollusc species lists fixed the total number at 114 of the Central Group of islands species, of which 49 are endem- (Terceira, Graciosa, São Jorge, ic. If the halophilic Ellobiidae Pico and Faial) clump very obvi- and supra-tidal Assimineidae ously in that they share most of and Truncatellidae are exclud- their endemics, thus refl ecting ed, there are 101 species, 47 of their geographical closeness. A which are endemic (Cunha et al., similar situation may be inferred 2010). Current research, how- for the Western Group (Flores ever, points to an even greater and Corvo). The oddity appears number of endemics awaiting in the Eastern Group, where description and when they are Santa Maria has the least number would lead to a consequent re- of shared endemics but exhibits arrangement of taxonomic and the greatest percentage of island biogeographical affinities (Table endemics. Being by far the oldest 1 and Figure 1; see also Martins, island (8 Ma), Santa Maria was 2005). When the land and fresh- expected to have a high percent- water malacofauna of the Azores age of island endemics. Similarly, is updated with these descrip- it was expected to constitute the tions (halophilic ellobiids and colonization source for the re-

PPaginação_21.inddaginação_21.indd 211211 119-01-20129-01-2012 11:52:0611:52:06 212AÇOREANA 2011, Suplemento 7: 209-228

maining islands. However, the Maria as the main focus for the evidence presented in Figure 1, colonization of the remaining corroborated by the morpho- islands of the archipelago, thus logical and anatomical affi nities requiring additional explanation of Drouetia (Figure 6), leads to a for the subsequent colonization re-assessment of the role of Santa of the other ones.

TABLE 1. Distribution of the land and freshwater molluscs of the Azores, including species under description (halophilic ellobiids and supratidal prosobranchs not included). E, endemic (Azores); e, undescribed; I, introduced; M, endemic (Macaronesian); N, native. Cor, Corvo; Fai, Faial; Flo, Flores; Gra, Graciosa; Pic, Pico; Sjo, São Jorge; Sma, Santa Maria; Smg, São Miguel; Ter, Terceira.

Species E/e N I Cor Flo Fai Pic Sjo Gra Ter Smg Sma Pisidium casertanum x xxx xxx Hydrocena gu a M xxxxxxxxx Craspedopoma hespericum E E E EEE Galba truncatula xxx Lymnaea peregra xx Physella acuta x xxx Helisoma trivolvis xx Ferrissia fragilis xxxx Deroceras caruanae xxxxxxx xx Deroceras laeve x xxx xx Deroceras reticulatum xxxxxxxxxx Arion distinctus x xxx x Arion intermedius x xxxxx xxx Arion cf. fl agellus x xxxxxxxx Balea heydeni x xxxxxxxxx Balea nitida EEE Cochlicopa lubrica x xxxxxxxxx Cachlicopa lubricella x xxxxxxxx Discus rotundatus x xxxxxxxxx Helicodiscus parallelus xx Helicodiscus syngleyanus xx x Toltecia pusilla x xxxxx xx Napaeus alabastrinus EEE Napaeus atlanticus [=forbesianus] E EEEEE Napaeus delibutus E EEEEEE Napaeus hartungi E E Napaeus pruninus E E Napaeus tremulans E E Napaeus vulgaris E E Napaeus sp. a eee Napaeus sp. b eeee Napaeus sp. c e e Euconulus fulvus x xxxxxxxxx Cecilioides acicula xxx Helix aspersa xxxxxxxxxx Oestophora barbula xxxxxxxxxx Oestophora lusitanica xx Otala lactea x xxx

PPaginação_21.inddaginação_21.indd 212212 119-01-20129-01-2012 11:52:0611:52:06 MARTINS: WHEN THE “FINCHES” ARE SNAILS 213

Species E/e N I Cor Flo Fai Pic Sjo Gra Ter Smg Sma Theba pisana xxxxxxxxxx Candidula intersecta xxx Caracollina lenticula xxxxxx Cernuella virgata xx Cochlicella barbara x xxxxxxxxx Helicella apicina xxx Heterostoma paupercula Mxxxx Leptaxis azorica E E Leptaxis caldeirarum E E Leptaxis drouetiana Exx Leptaxis minor E E Leptaxis sanctaemariae E E Leptaxis simia [=erubescens] Mxx Leptaxis terceirana EEE Leptaxis sp. eee Microxeromagna armillata M xxxxxxxxx Moreletina horripila E EEE EE Moreletina obruta E E Moreletina vespertina E EEE E Moreletina sp. a ee Moreletina sp. b eee ?Moreletina sp. a e e ?Moreletina sp. b e e ?Moreletina sp. c e e Lehmannia valentiana xxxxxxxxxx Limacus fl avus xxxxxxxxxx Limax maximus xxxxxxxxxx Milax gagates xxxxxxxxxx Punctum azoricum E EEEEEEEEE Lauria anconostoma x xxxxxxxxx Lauria fasciolata E EEEEEEEEE Leiostyla fuscidula E EEEEEEEE Leiostyla rugulosa E EEE E Leiostyla tesselata E E Leiostyla vermiculosa EEEE Leiostyla sp. a eee Leiostyla sp. b eee Leiostyla sp. c ee Leiostyla sp. d e e Rumina decollata xxxx x xxx Testacella maugei xxxxxxxxxx Acanthinula azorica E EEEEEEEE Spermodea monas E EEEEEEEE Vallonia costata x xxxxxxxx Vallonia excentrica xx x Vallonia pulchella xxxxxxxxxx aspera x xxxx xx Columella microspora M xxxx xxxx Vertigo pygmaea x xxxxxxxxx Azorivitrina angulosa E E Azorivitrina brevispira E E Azorivitrina brumalis E EEE EE Azorivitrina fi nitima EEE Azorivitrina laxata E E Azorivitrina pelagica E E

PPaginação_21.inddaginação_21.indd 213213 119-01-20129-01-2012 11:52:0611:52:06 214AÇOREANA 2011, Suplemento 7: 209-228

Species E/e N I Cor Flo Fai Pic Sjo Gra Ter Smg Sma Plutonia atlantica E EEE EE Aegopinella nitidula xx Hawaia minuscula xx hammonis x xxxxxxxxx Oxychilus alliarius xx x Oxychilus (D.) agostinhoi E E Oxychilus (D.) atlanticus E E Oxychilus (D.) batalhanus E E Oxychilus (D.) brincki E E Oxychilus (O.) cellarius xxxxxxxxxx Oxychilus (O.) draparnaudi x xxxxxxxxx Oxychilus (D.) furtadoi EE Oxychilus (?) juvenostriatus E EEEEE Oxychilus (?) lineolatus E E Oxychilus ((D.) miceui EE Oxychilus (?) miguelinus E E Oxychilus (D.) minor EEE Oxychilus (?) ornatus EE Oxychilus (?) scoliura EE Oxychilus (A.) spectabilis E E Oxychilus (R.) volutella E E Oxychilus (?) sp. a e e Oxychilus (?) sp. b e e Oxychilus (?) sp. c e e Oxychilus (?) sp. d ee Oxychilus (D.) sp. a ee Oxychilus (D.) sp. b eee Oxychilus (D.) sp. c ee Oxychilus (D.) sp. d ee Oxychilus (D.) sp. e ee Oxychilus (D.) sp. f ee Oxychilus (D.) sp. g ee Oxychilus (D.) sp. h e e Oxychilus (D.) sp. i e e Oxychilus (D.) sp. j e e Oxychilus (D) sp. k eee Oxychilus (D) sp. l e e Vitrea contracta x xxxxxxxxx Zonitoides nitidus xxx x Undescribed island endemic - - - 1 4 - - -4-39 Island endemic - - - - 7 1 - - - 3 9 13 Undescribed shared endemic - - 551221-1- Shared endemic - - 4 7 13 15 15 10 16 12 6 Non endemic - - 27 30 39 40 33 31 39 49 40 TOTAL 75 20 35 37 53 55 57 50 46 58 74 68

VARIATION IN DROUETIA. ation in the Azores. The genus

HW: PUNCTUATED Oxychilus is remarkable in this EQUILIBRIUM ALIVE? respect, for it alone accounts for over one third of the endemic Table 1 shows that some taxa species present in the archipel- have undergone extensive radi- ago. Worth noting is that this

PPaginação_21.inddaginação_21.indd 214214 119-01-20129-01-2012 11:52:0711:52:07 MARTINS: WHEN THE “FINCHES” ARE SNAILS 215

genus has no equivalent status ancestral reference point with among the endemic taxa of either the Recent mainland European Madeira or the Canary Islands. taxa. Azorean usually It is, therefore, a good candidate exhibit a more vivid coloration for the study of the processes, than European species, and can mechanisms and dynamics of be grouped into two main cate- evolution in the Azores. gories, in relation to either the presence or absence of an umbili- cal perforation. The non-umbili- cate forms are grouped under the subgenera Drouetia Gude, 1911 and Atlantoxychilus Riedel, 1964, whereas the umbilicate forms need more detailed stud- ies to ascertain their phyletic relationships. Drouetia was pro- posed as a monotypic genus for Helix atlantica Morelet & Drouët, 1857, at the time thought to live throughout the archipelago. The anatomical studies of Riedel (1964) revealed a wealth of vari- ability concealed within a usu- ally less remarkable shell form. The subgenus Atlantoxychilus FIGURE 1. Cumulative representations of the distribution of terrestrial mollusc was created to accommodate species throughout the various islands of the odd variety γ spectabilis of the Azores. See Table 1 for abbreviations. Morelet (1860), and the remain- der of Morelet & Drouët’s H. at- lantica was split by Riedel (1964) The endemic Azorean Oxy- into three subspecies under chilus species flock is thought the subgenus Drouetia, which to have its origin in some pre- he later raised to specific level Ortizius type of snail arriving on (Riedel, 1980). Subsequent stud- the archipelago sometime dur- ies (Martins, 1981, 1989a; de ing the Tertiary (Riedel, 1964), Winter, 1989) have contributed and to have lost their immediate additional species.

PPaginação_21.inddaginação_21.indd 215215 119-01-20129-01-2012 11:52:0711:52:07 216AÇOREANA 2011, Suplemento 7: 209-228

An anatomical study of of the theory of punctuated Drouetia conducted throughout equilibrium (Eldredge & Gould, the Azores by Martins (2005) re- 1972). If the various steps toward vealed not only the presence of speciation are circumscribed by additional island endemics but the boundaries of the different also patterns of diversity, appar- islands, then the populations or ently consistent with the age of communities contained within their host islands. These pat- the Drouetia clade are bound terns were interpreted as rep- to exhibit the characteristics resenting various stages in the of the various stages proposed shaping of a species, that is, the by the theory, i.e.: (1), the process of speciation, as the role diversity burst of the early of colonization appeared to be stage, associated with severe of lesser influence. Thus: (1), ecological disturbance caused, young islands would display in this case, by frequent volcanic a greater amount of allotopic, eruptions; (2), an intermediate demic, diversity but no overlap stage where species individuate of distinct anatomical patterns, during relatively long volcanic i.e., evidence of an early stage calmness (few thousands of of speciation; (2), medium age years), the species still being islands would show speciation closely related phylogenetically, already clearly defined: there and (3), the stasis stage where would be syntopic, inter-spe- interspecific affinity and intra- cific, variability but the species specific variability are small, would be closely related and (3), volcanic activity having ceased old islands would also exhibit for more than a million years. syntopic, interspecific, variabil- Evidence that species of ity but the species would appear Drouetia on various islands may to be far less related than in the meet these criteria comes from previous situation, having even analyses of their reproductive progressed to the status of sub- anatomies. Pico, the youngest genus. Azorean island (0.25 Ma), is an If we view time as expressed adequate candidate to exem- differently by the variously aged plify the first stage. Martins et islands, a further step towards al. (2006) surveyed Oxychilus understanding the dynamics (Drouetia) minor Riedel, 1964 of evolution is possible: a test throughout and

PPaginação_21.inddaginação_21.indd 216216 119-01-20129-01-2012 11:52:0711:52:07 MARTINS: WHEN THE “FINCHES” ARE SNAILS 217

found that, although in general that, as with O. (D.) minor, the the samples of the various demes populations on Pico have also showed different patterns, with- migrated from Faial. A possible in-deme variability was small explanation for the anomalous and no overlapping patterns distribution on Pico is related to were detected. However, fur- its geological history, for the mas- ther research has shown the ex- sive stratovolcano that dominates istence of two non-overlapping the whole north-western third anatomical patterns correspond- of the island is only 40 thousand ing to two different species, and years old and there has been in- a curious geographical distribu- tense volcanic activity up to his- tion (Figures 2-3; Table 2). One torical times on this half of the pattern comprising demes a-e, island (França et al., 2003). This typical of higher altitudes, ex- might, therefore, have had a great tends longitudinally along the destructive impact on the island’s middle of the island. This shows earliest biota. It is hypothesized strong anatomical affinity with that O. (D.) minor (pa ern one) O. (D.) minor, described from arrived from nearby Faial, only Faial Island, and with which it 8 km to the northwest and was may be considered conspecific. the fi rst of these two species to The second pattern, with demes inhabit Pico. The populations on f-h, occupies the north-east- the south-eastern tip of Pico sur- ern side of the island along the vived the eruption of the moun- coast. Drouetia is absent from the tain and, from there, progressive- south-western side of the island. ly re-colonized the north via the Oxychilus (D.) minor has been centre of the island. The second the only Drouetia species re- pa ern is still allotopic on Pico in corded from Faial (Figure 4a). relation to pa ern one, whereas More extensive research, how- both are sympatric throughout ever, has revealed the existence Faial Island including in pristine, of a sympatric, cryptic species, endemic areas such as Caldeira. very similar to O. (D) minor mor- It resulted probably from a much phologically but readily distin- later colonization event, also guishable from it anatomically from Faial, and is now spreading (Figure 4b). It is apparently southward along the coastline. identical to that found in f-h, on The absence of Drouetia from Pico Island, and it is plausible the south-western side is less

PPaginação_21.inddaginação_21.indd 217217 119-01-20129-01-2012 11:52:0711:52:07 218AÇOREANA 2011, Suplemento 7: 209-228

FIGURE 2. The Azores archipelago showing the ages of the various islands. Insert: Pico Island, showing the stations mentioned in the text. See Table 2 for abbreviations.

clearly justified, but could be ed existence of a great amount tentatively explained by the of allotopic, demic, diversity but overall youth of the island. no overlap of distinct anatomical Although intensive searches pa erns, it can be said that those were conducted throughout criteria for the fi rst stage of the Pico in 1995, 2005 and 2008, theory (allotopic, demic diversi- further research on this second ty) are somewhat obscured by the largest island of the Azores, peculiar pa ern of biogeographi- including molecular surveys, cal distribution expressed on should yield more information Pico. However, molecular analy- on the relationships, rank-order ses contrasting the populations and distribution of Drouetia, and on Pico and on Faial are expected help to clarify the geographical to clarify the diversity pa erns of issues described earlier. the two cryptic species on both Relating the aforementioned islands and will allow further in- evidence to the concept of punc- ferences about the suitability of tuated equilibrium (Eldredge & the application of the theory of Gould, 1972), namely the expect- punctuated equilibrium.

PPaginação_21.inddaginação_21.indd 218218 119-01-20129-01-2012 11:52:0711:52:07 MARTINS: WHEN THE “FINCHES” ARE SNAILS 219

FIGURE 3. Variability in the coloration of the , morphology of the genitalia and internal morphology of the penis of Oxychilus (Drouetia) minor (a-e) and an undescribed species of Drouetia (f-h) from the various stations on Pico Island, as shown in Table 2. Scale bars = 1 mm.

França et al. (2003) considered ternal morphology of their shells that Flores is 2.16 million years and body coloration. Their anat- old and has been free of volcanic omies, however, though diff er- activity for 3.000 years. Flores ent, reveal a similar pa ern, indi- Island, then, is an appropriate cating the possibility of a single candidate for verifi cation of the ancestor (Figure 5). It appears, second stage of punctuated equi- then, that here the criteria for the librium. That is, during rela- second phase of punctuated equi- tively long periods of volcanic librium are met. calmness, species individuate but The third stage – stasis – is remain closely related phyloge- seen on the island of Santa Maria, netically. Four widely sympatric about 8 million years old and species are found on Flores, and with no volcanic activity for over are readily separated by the ex- 3.5 million years. There are four

PPaginação_21.inddaginação_21.indd 219219 119-01-20129-01-2012 11:52:0811:52:08 220AÇOREANA 2011, Suplemento 7: 209-228

TABLE 2. Sampling sites (Stations) on Pico Island.

Altitude Sta Locality Co-ordinates Characterization date (m) Forest of Accacia melanoxylon, Myrica faya; sparse N 38° 25.874’ 07-06- a Piedade 200 undergrowth of Hedychium gardneranum; stone W 28° 04.222’ 2005 walls Lagoa do N 38° 31.519’ Among Selaginella kraussiana and turf of semi- 14-02- b 850 Peixinho W 28° 23.365 permanent pasture 1995 Caldeirões, Forest of Cryptomeria japonica, Persea indica, Accacia N 38° 27.620’ 24-11- c Prainha do 330 melanoxylon, Pi osporum undulatum; undergrowth W 28° 12.820’ 2008 Norte of Hedychium gardneranum, ferns. Forest of Pi osporum undulatum, Accacia Ossada, Santa N 38° 31.519’ 08-06- d 350 melanoxylon; Hedychiumm gardneranum; stone walls, Luzia W 28° 23.365’ 2005 strewn rocks. Cabeço da Bola, Endemic vegetation: Laurus azorica, Vaccinium N 38° 28.703’ 09-06- e Caminho da 1050 cylindraceum, Viburnum tinus, Calluna vulgaris, W 28° 26.100’ 2005 Montanha Woodwardia radicans, Blechnum spicant, Festuca jubata Mata do Forest of Pi osporum undulatum, undergrowth N 38° 32.098’ 08-05- f Hospital, 30 of Hedychium gardneranum, Pteridium aquilinum, W 28° 20.216’ 2005 Madalena Tradescantia fl uminensis; stone walls Forest of Accacia melanoxylon, Pi osporum Furnas de Santo N 38° 32.098’ undulatum, undergrowth of Hedychium 10-06- g 20 António W 28° 20.216’ gardneranum, Pteridium aquilinum, Selaginella 2005 kraussiana; strewn rocks Forest of Pi osporum undulatum, sparse Accacia Chão Verde, São N 38° 29.456’ 06-06- h 500 melanoxylon, Cryptomeria japonica; undergrowth of Roque do Pico W 28° 17.098’ 2005 ferns; strewn stones

FIGURE 4. Variability in the coloration of the animal, morphology of the genitalia and internal morphology of the penis of Oxychilus (Drouetia) minor (a) and an undescribed species of Drouetia (b) from Ribeirinha, Faial Island. Scale bars = 1 mm.

PPaginação_21.inddaginação_21.indd 220220 119-01-20129-01-2012 11:52:1011:52:10 MARTINS: WHEN THE “FINCHES” ARE SNAILS 221

FIGURE 5. Variability in the coloration of the animal, morphology of the genitalia and internal morphology of the penis of four undescribed species of Drouetia from Flores Island. Scale bars = 1 mm.

non-umbilicate species on Santa The evidence just presented, Maria, one placed under the sub- from selected islands, for the spe- genus Atlantoxychilus and the oth- ciation of Drouetia as an exam- er three under Drouetia (Figure ple of punctuated equilibrium, is 6). Their intraspecifi c variability only one of a number of hypoth- is comparatively small, that is, all eses being examined in the quest variability is readily identifi able towards understanding the pro- within each of the various species. cesses through which evolution This can, therefore, be interpreted happens and for the mechanisms as a stasis phase. Their anatomies that make it possible in the Azores are completely diff erent but, on Archipelago. Anatomy and mor- that basis alone, it is not possible phology alone, though usually to ascertain their phylogenetic re- powerful indicators of pa erns, lationships, namely if they have a are sometimes unable to give un- common ancestry. equivocal answers to their ori-

PPaginação_21.inddaginação_21.indd 221221 119-01-20129-01-2012 11:52:1111:52:11 222AÇOREANA 2011, Suplemento 7: 209-228

FIGURE 6. Variability in the coloration of the animal, morphology of the genitalia and internal morphology of the penis of species of Oxychilus from Santa Maria Island. a, Oxychilus (Drouetia) agostinhoi; b, undescribed species of Drouetia; c, Oxychilus (Drouetia) brincki; d, Oxychilus (Atlantoxychilus) spectabilis. Scale bars = 1 mm.

gins. A molecular study is under- scribed by Augustus A. Gould in way to search for a phylogeny for 1848 from material collected dur- Drouetia, to investigate aspects of ing the United States Exploring population genetics and, thereby, Expedition (1838-1842) in an un- to ascertain the phylogeographic planned stop at the Azores (São relationships of demes, popula- Miguel) (Colvocoresses, 1852). tions and species. The specimens were originally thought to probably be from VARIATION IN NAPAEUS South America. Johnson (1964),

PRUNINUS. HW: RETICULATE apparently unaware of Morelet´s EVOLUTION? (1860) extensive treatment of the land molluscs of the Azores, Bulimus pruninus was the first subsequently and tentatively Azorean endemic mollusc, de- attributed Gould’s species to

PPaginação_21.inddaginação_21.indd 222222 119-01-20129-01-2012 11:52:1311:52:13 MARTINS: WHEN THE “FINCHES” ARE SNAILS 223

Madeira Island. Morelet (1860: tion ranges from dark-brown to 180) commented upon this spe- yellowish, sometimes whitish, cies as follows: the background consistently “Le Bulimus pruninus est darker in the first four or five assurément l’espèce la plus re- whorls, marbled with lighter, marquable de l’Archipel“.1 longitudinal vermiculations or He illustrated profusely the lines. The texture ranges from morphological diversity of shell typically rugose in mountain coloration and texture, and con- specimens, vermiculations cor- sidered under the same species responding to raised ornamen- name specimens from Terceira as tation, to nearly smooth or with well as those from Santa Maria, fi ne growth lines on those speci- earlier described by Mousson mens from near-shore environ- (1858) as Bulimus tremulans. ments. Backhuys (1975) revalidated The reproductive systems of Mousson’s species from Santa Napaeus alabastrinus, confined Maria on account of the mor- to Terceira and Pico, and of N. phology of the reproductive sys- tremulans, only reported from tem and, after the description of Santa Maria, differ radically the specimens from Terceira as in the size and shape of the Napaeus alabastrinus by Martins epiphallus, and in the length (1989b), the locality of Napaeus of the diverticulum. Their pruninus became restricted to spermatophores are also ex- São Miguel, from where it was tremely different, the one from supposedly collected. N alabastrinus being short with The coloration and texture a curved head and the whole of the shell are relatively con- body with one loose helicoidal stant in Napaeus alabastrinus, turn whereas that of N. tremu- the former ranging from white lans is long and strongly coiled. to slightly coloured with pur- The morphologies of the genita- plish hues, and the latter from lia and of the spermatophores smooth to weakly rugose due to are highly constant throughout persistent growth lines. With N. the populations of both species tremulans, however, the colora- (Figure 7 a, i). With Napaeus pruninus, how- ever, the situation is quite dif- 1 Bulimus pruninus is surely the most remarkable species of the Archipelago. ferent (Figure 7 b-h). The shells,

PPaginação_21.inddaginação_21.indd 223223 119-01-20129-01-2012 11:52:1511:52:15 224AÇOREANA 2011, Suplemento 7: 209-228

FIGURE 7. Variability in the morphology of shell, genitalia and spermatophore of species of Napaeus. a, Napaeus alabastrinus, Terceira (shell and genitalia, Fonte Dionísio; spermatophore, Silveira, Angra do Heroísmo); b-h, Napaeus pruninus, São Miguel (b, Sete Cidades; c-d, Pico do Fogo; e, Algarvia; f, Ribeira do Tosquiado; g, E of Gramas, Ribeira Grande; h, Rosário, Vila Franca do Campo); i, Napaeus tremulans, Pico Alto, Santa Maria. Scale bars = 1 m.

although typically deep purple, Preliminary molecular analysis smooth in the western portion seems to have complicated the of São Miguel, range through situation even further, by inte- the entire colour and texture grating a third species into the patterns of the other two spe- equation (Figure 8). The analy- cies, as do the genitalia and the sis clearly separates N. alabastri- spermatophores. Nevertheless, nus from the other two species, there is no clear correspond- but leaves unresolved the pres- ence between shell and genita- ence in N. pruninus of similar lia/spermatophore morpholo- genitalia and spermatophore gies indicative of an unambi- morphologies (Figure 7 a, b). guous relationship with either On the other hand, there is no N. alabastrinus or N. tremulans. definite separation between N.

PPaginação_21.inddaginação_21.indd 224224 119-01-20129-01-2012 11:52:1511:52:15 MARTINS: WHEN THE “FINCHES” ARE SNAILS 225

FIGURE 8. Molecular, morphological and anatomical variability in Napaeus. a-f, Cluster of specimens from Pico do Fogo, São Miguel (yellow rectangle) in a cladogram obtained from COI, ranging from typical Napaeus pruninus to Napaeus vulgaris (f); g, shell, genitalia and spermatophore of Napaeus vulgaris, Pico do Fogo, São Miguel; h, Napaeus vulgaris, syntypes BMNH 93.2.4.1134-6, São Miguel; i, Napaeus pruninus, fi gured holotype USNM 5485 (Johnson, 1964). Scale bars = 1 mm.

tremulans and N. pruninus, thus fusion: did Napaeus alabastri- rendering somewhat irrelevant nus and N. tremulans originate the differences in genitalia and from N. pruninus?. Or could spermatophore morphology. we, instead, be confronted in Furthermore, the topology of São Miguel, where all patterns what was supposed to be an out- merge, with a case of reticulate group, Napaeus vulgaris, cluster- evolution? ing with the typical N. pruninus, Morelet (1860) put forward a brings even more confusion to working hypothesis in relation an already unclear situation. to this problem, that is, intro- A basic question comes to gression. On the basis of shell mind as a possible way to un- morphology alone, he had al- ravel the above described con- ready recorded the wide vari-

PPaginação_21.inddaginação_21.indd 225225 119-01-20129-01-2012 11:52:1611:52:16 226AÇOREANA 2011, Suplemento 7: 209-228

ability of N. pruninus and its explication à cette singularité overlap with that of N. vulgaris. qu’une alliance adultérine entre He wrote, when commenting les deux mollusques” (p. 187)3. about N. vulgaris: “Chez certains individus, IF DARWIN WERE TO VISIT les traits du B. pruninus pre- THE AZORES AGAIN… dominent […]; elle [the shell] conserve d’ailleurs la taille ha- The two situations just con- bituelle du vulgaris; mais les sidered provide ample justifi- mêmes caractères, en s’affaiblis- cation to view the Azorean is- sant graduellement, finissent lands as a cradle of evolution, par se confondre chez d’autres real test tubes where theories specimens, d’une manière telle- dealing with the processes and ment intime avec ceux de l’es- the mechanisms governing evo- pèce voisine, qu’il n’est plus pos- lution can be tested. The privi- sible d’assigner à chacune d’elles leged geographical location of ses limites” (p. 186)2. the archipelago and the spatial The French naturalist then grouping and diverse ages of proceeds to give the explana- its islands provide us with an tion: ideal laboratory to catch evolu- “Lorsque l’on considère cette tion red-handed. dégénérescence du Bulimus If Darwin were to visit the pruninus, dont les traits carac- Azores again, he probably téristiques se confondent avec would not have to hand all the ceux d’une espèce totalement dif- ingredients necessary to come férente, qui emprunte à celle-ci up with the concept of evolu- sa petite taille et sa transparence tion, but he certainly would pour lui donner sa forme et ses have readily available the solu- couleurs, on ne trouve d’autre

3 Once this degenerescence of the 2 In some specimens, the features of Bulimus pruninus is considered, where the B. pruninus predominate […]; [the the characteristic features are confused shell] retains otherwise the usual size with those of a totally diff erent species, of the vulgaris; but the same characters, which borrows from this one its small gradually becoming fainter, end up size and transparency to give it its shape mixing in other specimens, in so intimate and colours, one does not fi nd any a manner with those of the neighbor other explanation for this singularity species, that it is no longer possible to but an adulterine alliance between both assign to each their own limits. molluscs.

PPaginação_21.inddaginação_21.indd 226226 119-01-20129-01-2012 11:52:1811:52:18 MARTINS: WHEN THE “FINCHES” ARE SNAILS 227

tion for some of the clarifica- LITERATURE CITED tions his theory would benefit from. And, then, the emblem- BACKHUYS, W., 1975. Land and atic Galápagos finches could fresh-water molluscs of the Azores, well be Azorean land snails. 350 pp. Backhuys and Meesters, Amsterdam. ACKNOWLEDGEMENTS COLVOCORESSES, G.M.S., 1851. Four years in the Government. Exploring The rediscovery of the Expedition; commanded by Captain Azorean terrestrial malacol- Charles Wilkes, to the island of Madeira- ogy has been the result of a Cape Verd island-Brazil — coast of team effort over the past 25 Patagonia-Chili-Peru-Paumato group- years. Regina Cunha, Armindo Society Islands-Navigator group- Rodrigues, Carlos Brito and Australia-Antarctic continent — New Paula Lourenço, with the tech- Zealand-Friendly Islands-Fejee group– nical help of Jorge Medeiros, Sandwich Islands-northwest coast Ana Ferreira and Paulo Melo, of America-Oregon-California-East under the expert guidance Indies-St. Helena, etc., etc. in one vol- of Thierry Backeljau, Peter ume. (Fi h edition). J. M. Fairchild & Mordan, Robert Cameron, Co, New York. James Harris and Benjamin CUNHA, R., P. RODRIGUES & Gómez have revealed the true A.F. MARTINS, 2010. Lista dos potential of the Azorean land Moluscos. In: BORGES, P.A.V., A. molluscs as models to study COSTA, R. CUNHA, R. GABRIEL, evolution. I also thank Brian V. GONÇALVES, A.F. MARTINS, Morton and Robert Cameron I. MELO, M. PARENTE, P. for their most helpful com- RAPOSEIRO, P. RODRIGUES, R.S. ments and for making sure SANTOS, L. SILVA, P. VIEIRA & V. the manuscript conforms to VIEIRA (eds.), A list of the terrestrial Darwin’s native language. and marine biota from the Azores, pp. This research is part of the 165-177. Princípia, Cascais. project “Speciation in Drouetia: DARWIN, C., [1839]. Voyage of the evidence of punctuated equi- Beagle. (BROWN, J., & M. NEVE, librium?” – (PTDC/BIA-BDE/ 1989, eds.). Penguin Books, London. 73467/2006), financed by the DARWIN, C., 1859. On the origin of Fundação para a Ciência e a species by means of natural selection, Tecnologia (FCT), Portugal. or the preservation of favoured races

PPaginação_21.inddaginação_21.indd 227227 119-01-20129-01-2012 11:52:1811:52:18 228AÇOREANA 2011, Suplemento 7: 209-228

in the struggle for life. John Murray, “’Napaeus’ pruninus” em São Miguel London. e na Terceira. Açoreana, 7: 41-54. de WINTER, A., 1989. Remarks on MARTINS, A.M.F., 1981. Oxychilus the non-marine molluscan fauna (Drouetia) agostinhoi new species of the Azores. 3. A new species of (: Zonitidae) from Drouetia from the Isle of São Miguel the Azores Islands, its anatomy (: Zonitidae). Basteria, 53: and phylogenetic relationships. 63-67. Occasional Papers on Mollusks, 4: 245- ELDREDGE, N., & S.J. GOULD, 1972. 264. Punctuated equilibria: an alterna- MARTINS, A.M.F., 2005. The shaping of tive to phyletic gradualism. In: a species: the Azorian Drouetia Gude SCHOPF, T.J.M. (ed.), Models in (Pulmonata: Zonitidae: Oxychilus) Paleobiology, pp. 82-115. Freeman, as a model. Records of the Western Cooper & Co., San Francisco. Australian Museum, Supplement No. FRANÇA, Z., J.V. CRUZ, J.C. NUNES 68: 143-157. & V.H. FORJAZ, 2003. Geologia MARTINS, A.M.F., R. TRISTÃO da dos Açores: uma perspectiva actual. CUNHA, M.H. SOUSA & P.J. MELO, Açoreana, 10(1): 11-140. 2006. Distribuição dos moluscos GOULD, A.A., 1848. Expedition terrestres da ilha do Pico (Açores) e shells: described for the work of the variabilidade de Oxychilus (Drouetia) United States Exploring Expedition, minor (Morelet, 1860). Relatórios e commanded by Charles Wilkes, Comunicações do Departamento de U.S.N. during the years 1838-1842. Biologia, 34: 53-67. Proceedings of the Boston Society of MORELET, A., 1860. Notice sur l’histoire Natural History, II: 190-192. Boston. naturelle des Açores suivie d’une des- JOHNSON, R.I., 1964. The Recent cription des mollusques terrestres de cet of Augustus Addison archipel, 216 pp. J.-B. Baillière, Paris. Gould. Illustrations of the types MOU ON, A., 1858. Über einige von described by Gould with a bibli- Herrn Hartung auf den Azoren ge- ography and catalog of his species. sammelte S ne en. Vierteljahrs- Bulletin of the United States national s ri der naturfors ende Gesells a , Museum, 239: i-v, 1-182. Zuri , 3(2): 163-169. MARTINS, A.M.F., 1989a. Espécies RIEDEL, A., 1964. Zonitidae (Gastro- novas do género Oxychilus poda) der Azoren. Boletim do Museu (: Zonitidae) na Ilha Municipal do Fun al, 18(66): 5-60. Terceira. Açoreana, 7: 55-71. RIEDEL, A., 1980. Genera Zonitidarum, MARTINS, A.M.F., 1989b. O complexo 197 pp. Dr. W. Backhuys, Ro erdam.

PPaginação_21.inddaginação_21.indd 228228 119-01-20129-01-2012 11:52:1811:52:18