THE NAUTILUS 109(1):1-13, 1995 Pane 1 Systematic Revision of Allochroa Ancey, 14387 (Pulmonata: Ellobiidae), with an Account of the Anatomy of Allochroa layardi (H. & A. Adams, 1855) and the Description of Two New Species Ant6nio M. de Frias Martins Departamento de Biologia Universidade dos &ores P-9502 Ponta Delgada codex SZo Miguel, A~ores,Portugal ABSTRACT subfamilies: Carychiinae, Pedipedinae, Pythiinae and Cassidulinae. Odhner's outline was supported on con- Of the nominal species of Allochroa Ancey, 1887 described to chological features by Zilch (1959). The first detailed use date, only two are recognized: A. bronnii (Philippi, 1846), en- demic to the Hawaiian Islands, and A. layardi (H. & A. Adams, of anatomical characters, in a review that included spe- 1855), distributed throughout the Indo-Pacific. Examination of cies belonging to 11 genera, was by Morton (1955). His the USNM collection revealed two additional species, A. nana study supported Odhner's classification, but the Cassi- Martins, n. sp. and A. tenuis Martins, n. sp., herein described. dulinae were included in the Pythiinae, on the basis of The anatomy of A. layardi is described and serves as the basis similarities of the reproductive system. In a study of for determining the relationships of this genus within the El- species belonging to 17 of the 23 genera currently rec- lobiidae. Allochroa has a monaulic, entirely glandular pallial ognized in the Ellobiidae, Martins (in press a) clarified gonoduct and a wide visceral nerve ring with a long right Morton's (1955) findings by redefining the subfamilial parieto-visceral connective, confirming placement in the Py- morphological patterns of the reproductive and nervous thiinae. Its close relationship to the Mediterranean and Eastern North Atlantic genus Ovatella Bivona, 1832 is indicated by systems. similar apertural dentition, protoconch morphology of A. ten- Preserved specimens of Allochroa layardi (H. & A. uis, and by the internal structure of the penial complex, where Adams, 1855) are used here as the basis for detailed the penis appears as the development of one of the pilasters. anatomical investigations of the family extending the preliminary findings reported in Martins (in press b). Key Words: Ellobiidae, P~thiinae,Allochroa, systematics, anatomy. Insight on the anatomy of A. layardi provided infor- mation needed to define the phylogenetic relationships of Allochroa Ancey, 1887 within the Pythiinae. The pres- ent work reviews the taxonomy of the species of Alloch- INTRODUCTION roa and describes the anatomy of A. layardi. Examina- tion-of the Mollusk collection at the National Museum The Ellobiidae are a group of primitive, mostly halo- of Natural History, Smithsonian Institution, consisting of philic pulmonate mollusks, commonly found near and only dry material, revealed the existence of two new above the hightide limit of mangroves, salt marshes, and species, herein described. boulder and cobble beaches. Morphologically very di; verse and ranging in length from barely 1 mm (Leu- MATERIALS AND METHODS conopsis) to about 100 mm (Ellobium), they nevertheless l share basic shell characters and body features that allow This taxonomic revision is based primarily on dry spec- them to be considered within a single family. Pfeiffer imens of Allochroa in the USNM collection. Four spec- (1853) was the first to attempt a subfamilial organization, imens of A, layardi, collected on Henderson Island in based on shell characters alone. He assigned those species 1991, were provided for anatomical work. The fully re- with a thick, reflected outer lip to the Auriculea [=El- tracted animals were preserved in alcohol and, except lobiinae], while he included the species with sharp outer for the eyes and the tip of the tentacles, appear to have lip in the Melampea [=Melampodinae]. Utilizing radular lost all other pigmentation. Two specimens were dis- and also some anatomical characters, Odhner (1925) rec- sected under a binocular microscope and drawn using a ognized a more complex subfamilial arrangement and camera lucida. redistributed the ellobiid genera among four additional Shells with protoconchs were mounted using double- Page 2 THE NAUTILUS, Vol. 109, No. 1 coated tape. Radulae were stretched across a cover slip posterior parietal tooth; outer lip sharp, usually with one after cleaning with KOH solution. Both structures were prominent fold entering the aperture at about the level mounted on stubs and examined and photographed using of the parietal teeth, forming a somewhat marked anal a Cambridge Stereoscan 250 Mk2 Scanning Electron Mi- canal. Protoconch bulbous, smooth, with up to 1.3whorls croscope. visible. Radula: Central tooth narrow, base deeply emargin- Acronyms for specimen repositories are as follows: ate, with two median flaring arms, unicuspid; lateral ANSP: The Academy of Natural Sciences, Philadel- teeth with elongated, sinuous base with two projecting phia asymmetric arms, inner arm lower, crown large and long, BMNH: The Natural History Museum, London subquadrangular; marginal teeth with sharp endocone MCZ: Museum of Comparative Zoology, Harvard gradually becoming as long as mesocone as row pro- University, Cambridge gresses outward, developing a sometimes conspicuous MNHN: Musium National d'Histoire Naturelle de basal ectocone. Paris Anatomy: Reproductive system monaulic, pallial gon- USNM: National Museum of Natural History, Smith- oducts entirely glandular, pallial gland present. Central sonian Institution, Washington, D.C. nervous system with wide visceral ring; right parieto- visceral connective as long as left. KEY TO THE SPECIES OF ALLOCHROA ANCEY, Remarks: The name Allochroa was proposed by Ancey 1887: (1887) to replace the supposedly preoccupied "Laimo- dmta des auteurs [H. & A. Adams, 18531 (non Nuttall)" 1. Shell thick ..................................2 (type species Auricula bronnii Philippi, 1846). "Lai- Shell thin ...................................3 modonta Nuttall", wrongly taken as an emendation of 2. Aperture oval elongated (base narrow). ..A. bronnii Laemodonta Philippi, 1846, was restricted to a different Aperture auriculate (base expanded). .... A. layardi assemblage (type species Auricula striata Philippi, 1846), 3. Shell length at least 4 mm .....................4 following Nevill (1878). A more detailed account of the Shell length less than 4 mm ....................5 synonymy of Laemodonta and Laimodonta is presented 4. Protoconch width less than .5 mm ...... A. layardi elsewhere (Martins, in press a). Protoconch width at least .6 mm ................5 5. Protoconch without umbilicus and with apertural lip Ancey (1887) also made clear that Marinula King, 1832, very similar to Pedipes Scopoli, 1777, was not an not reflected ...........................A. nana Protoconch with umbilicus and with apertural lip eligible group for his new assemblage, and that Monica H. & A. Adams, 1855 [=Ovatella Bivona, 18321, although slightly reflected ......................A. tenuis decidedly conchologically closely related, is restricted to Mediterranean and West Atlantic species. SYSTEMATICS Allochroa is concholonicallv-. characterized bv the vres- Class GASTROPODA Cuvier, 1797 ence of an outer lip internal lamella which, in conjunc- Subclass PULMONATA Cuvier, 1817 tion with the anterior parietal tooth, divides the aperture Order Archaeopulmonata Morton, 1955 into two roughly equal halves: a posterior portion, where the shell is thinner; an anterior, thickened half. some- Family Ellobiidae H. & A. Adams in Pfeiffer, 1854 Subfamily Pythiinae Odhner, 1925 times with an additional internal fold on the outer lip. Genus Allochroa Ancey, 1887 The inner lip of the aperture is typically pythiine, i.e., roughly equidistantly tridentate, with one small colu- Allochroa Ancey, 1887:288. Type species by original designa- mellar tooth and two parietal teeth. The lamellar, outer tion: Auricula brmnii Philippi, 1846. lip tooth readily separates this genus from the closely related Laemodonta, which usually has two round tu- Description: Shell length to 12 mm, oval-conic, fragile bercles on the outer li~.and also from Ovatella. where to somewhat solid, sometimes hirsute. Umbilicus absent. the outer lip lamellae ;re much shorter. The single col- Spire with up to 7.4 flat to slightly convex whorls, sculp- umellar tooth sets Allochroa apart from Pedipes which, tured with more or less marked spiral lines; body whorl as in P. mirabilis (Miihlfeld, 1816) and P. pedipes (Bru- 55 to 80% of shell length, usually with three chestnut gui&re, 1789), has a strong, crest-like outer lip fold pen- spiral bands over a whitish to light-brown background, etrating inside the aperture. In Pedipes, the single pa- the band just above the aperture consistently strongest, rietal tooth is very strongly pronounced. the one near the suture sometimes faint, the one near The six species assigned by authors to Allochroa are the columella largest, sometimes coalescing with the me- here synonymized into two: the Hawaiian Allochroa dian band. Aperture about 50 to 60% of shell length, bronnii (Philippi, 1846) and the Indo-Pacific Allochroa oval-elongated to semi-circular, angled posteriorly, layardi (H. & A. Adams, 1855). Two additional new rounded anteriorly; inner lip slightly reflected over the species are described herein. columella, with three more or less equidistant teeth: one Kuroda and Habe (1952) listed Pedipes afinis F&- oblique columellar tooth, a more or less horizontal an- ussac, 1821, under Allochroa, owing probably to the pres-