Are Compared and Both Found Not Entirely Satisfactory
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STUDIES ON THE FAUNA OF CURAÇAO AND OTHER CARIBBEAN ISLANDS: No. 164 A new member of the crustacean suborder Ingolfiellidea from Bonaire, with a review of the entire suborder by Jan H. Stock (Instituut voor Taxonomische Zoologie [Zoologisch Museum], Universiteit van Amsterdam) Page Introduction 57 Systematics of the Ingolfiellidea [Fig. 17, Table 7] 58 to the and and list of the Keys genera subgenera species 61 66 Ingolfiella putealis n. sp. [Figs. 18-21] Bibliography of the Ingolfiellidea 73 A single specimen of an ingolfiellid was foundin a slightly brackish well (locally called a “pos”) on the Bacuna estate in the island of Bonaire (Netherlands Antilles). The specimen differs from all other 21 and ingolfiellid taxa, is described as a new species, Ingolfiella (Gevgeliella) putealis. The two classification systems in use for the Ingolfiellidea, that of KARAMAN (1959) and that of RUFFO (1970), are compared and both are found not entirely satisfactory in the light of recent discoveries. A new system is devised, in which the suborder is divided into 2 with 3 and 5 The and families, together genera subgenera. genera subgenera do not only represent morphological unities, but also combine species with similarhabitat requirements. Within the series, the marine genera are distinctly plesiomorph, the limnic genera show various degrees of apomorphy. 57 The fieldwork in Bonaire was supported by a grant (WR 87-114) from the Netherlands Foundation for the Advancement of Tropical Research (WOTRO), The Hague. I am greatly indebted to Mr. J. HERRERA, of Kralendijk (Bonaire) for guiding me his estate, to the well where the material this is based on Bacuna, whereupon paper was collected. I wish to thank Dr. H. A. Finally TEN HOVE (ZoologicalLaboratory, Utrecht) for number — not taking a of well samples from Bonaire, which though yielding any animals. Dr. E. Ingolfiellidea- contained several interesting H. COOMANS (Amster- dam) indentified the accompanying snails. INTRODUCTION The isolated the Ingolfiellidea occupy an position within Crusta- with distinct to the cea, as a separate suborder affinities Amphipoda (SIEWING, 1963). Several authors (KARAMAN, 1933, 1959; COINEAU, consider 1963; LELEUP, 1955) the group "primitive" or "archaeic", and of fact the as a matter the scattered present-day distribution, wide habitat range, and the wide bathymetrical range are solid indi- cations for the of the Members of the antiquity ingolfiellids. group in have been found in groundwater of river beds and sea beaches, coral and in from infra- caves, on flats, deeper waters reaching littoral sands to the deep-sea. They have been recorded from Europe, Asia, Africa, North and South America. On the other hand, as SIEWING (1963) pointed out, there is not a single argument in favour of the assumption that the ingolfiellids should be morphologically primitive. NOODT (1965) states, and he is in that the quite justified my opinion, ingolfiellids are developed highest and have reached an extreme degree of adaptation towards the "Lebensformtyp Mesopsammon" (REMANE, 1952), expressed by and an elongated, worm-like body, loss of pigmentation eyes, aber- rant reproduction, progressive reduction of the appendages (mostly the end of small starting at posterior the body), and a body size. Although nothing factual about the reproduction is known, SCHIECKE the (1973: 109), commenting upon poorly developed brood-plates incapable of holding the eggs, wonders whether this 58 "morphologisch extrem apomorphe Form ihre Eier frei ablegt - ein bei Peracariden einmaliger Vorgang". SYSTEMATICS OF THE INGOLFIELLIDEA Up to recently, the Ingolfiellidea were considered morphologically differences level than very uniform, showing no on a higher the the habitat specific one, notwithstanding enormous range (from continental cave waters, through mesopsammal habitats, to the In have been made deep-sea). recent years, two attempts to break the in units. The and group up generic oldest, only partial, attempt is that of S. KARAMAN, 1959 (p. 78-79), who distributed the six four known species over monotypic genera, leaving two species "vorderhand nicht In eingeteilt". a later, elegant, attempt, RUFFO, 1970, used a combinationof morphological and ecological characters to subdivide the known species (the number of which had risen to 14 that into families and four The small-sized at time) two genera. forms RUFFO'S in mesopsammal fall, according to system two genera: Balcanella Karaman, 1933, and Ingolfiella Hansen, 1903, the former without ocular lobes and distributed in phreatic, continental waters, the with ocular lobes and in latter distributed bathybenthic, meso- reef psammal or macroporous habitats. The discovery of a number of new taxa in the most recent years total number of known Some of brings the ingolfiellids on 21. the newly discovered forms do not support the division between Ingolf- iella and Balcanella on a combined morphological/ecological basis: the limnic Balcanella contains least genus at one species, ruffoi marine whereas the (Siewing, 1963) from beaches, new species de- scribed in the present paper, though having an ocular lobe like Ingolfiella, is not marine but is found in inland waters. Several Coineau & Ingolfiella species (e.g., putealis n. sp., kapuri Rao, 1972, berrisfordi Ruffo, 1974) have so small an ocular lobe, that one wonders whether this structure has not been overlooked in some of the so-called Balcanella species. We follow RUFFO in subdividing the Ingolfiellidea into two fami- the and the lies, Metaingolfiellidae (with one genus, Metaingolfiella), 59 For will in Ingolfiellidae. the latter family, we develop the sequel ideas about division into and sub- some new its possible genera genera. It is quite clear that the family Ingolfiellidae contains two distinct of of to 23 united groups species: a group large-sized species (up mm) in the genus Trogloleleupia, and consisting of 3 species, and a larger group of small-sized forms (up to 3 mm). When one analyses the characters of small-sized morphological the group, there appear to be clusters of species, some with more plesiomorph characters, others with clearly apomorph characters. The apomorph characters are not realized simultaneously, but step by step and probably at different evolution speed and along different evolution lines. We consider the following characters (within the small-sized In- the first golfiellidae) as plesiomorph: carpus ("hand") of the and less in the of second gnathopods are more or similar shape; palm gnathopod 2 is almost vertical; the finger of gnathopod 2 is very long (3/4 to 9/10 of the posterior margin of the carpus); neither the gnathopods nor the pleopods show secondary sexual differences; the ocular lobe is well-developed. In more apomorph clusters of species, the ocular lober is in gradual reduction; the differences in shape between gnathopods 1 and 2 get greater; the claw of the 2nd gnathopod gets shorter; certain second- ary sexual differences develop in the 2nd gnathopod and in the pleopods. So, the carpus of gnathopod 2 in male bears in the more apomorph species a "differentiated element" (a reversed pectinated In spine or a reversed bag-like spine). plesiomorph species, the pleo- pods are similar in both sexes: unarmed, triangular plates; in apo- morph species, the first male pleopod is setiferous and changes shape, whereas the 2nd and 3rd male pleopods may disappear. Five clusters of species are found this way (Table 8). Since these clusters unite not only species of similar morphology, but also forms from of in trend from marine originating a same type habitat, a to limnic, each cluster is given nomenclatorial status. Since a number of species is known from one sex only, the location of these species remains presumptive. However, the proposed arrangement leaves at present no "loose ends" in the form of unclassified species. I have preferred to use subgenera instead of genera for the re- 60 ground- ** from INTO Balcanella (far coast) ** spoon-shaped, symmetrical ** L. dissimilar oblique elongate absent continental water 5. I ? ? the S. ground- near 3 Ingolfiella or 2, absent pi. (often Gevgeliella or continental coast) dissimilar oblique <1 present triangular (asymm.) absent unlike (setose) small water GENUS 4. the THE and 3 waters OF dissimilar or 2, absent to BASED pi. limnic Trianguliella or 8 IS strongly oblique transverse <f absent triangular (asymm.) absent unlike (setose) small interstitial (both coastal) SUBDIVISION 3. TABLE and SUBGENERA sub- reefs, THE (coral medio- 3 5 Hanseniella 2, in WHICH dissimilar oblique i absent triangular (asymm.) pi. present*) microporous strates sand) infra-littoral 2. < as ON str. s. in carpus vertical ruffoi. equal posterior of 3 Ingolfiella 2, H. CHARACTERS f pi. almost margin absent triangular (asymm.) present abyssal for 1. about shape > as 2 3 1 2 Gn. mentioned 2 sexual and SALIENT in (J Gn. Gn. unknown. Gn. 2 1, of of lobe Not of 2 9) Secondary differences Pleopods *) **) Carpus and Palm Finger (<?. Pleopod Ocular Habitat 61 of arrangement of the species, for a couple reasons: (1) As compared with the other in the suborder genera Ingolfiellidea ((Metaingolfiella, the differences betweenthe various small-sized Trogloleleupia) , ingol- An fiellids are relatively slight. equilibrized treatment would be reached the mentioned Ingolf-by considering two genera just plus iella s.l. as full genera, and by subdividing the latter into 5 sub- genera, corresponding with the species clusters found. (2) The five which s.l. is subdivided least units into Ingolfiella are, at in part, characters of sexual this distinguished by a secondary nature; means that, if one has only material of one sex available, it might be im- I possible to classify it with certainty. Since consider this an un- desirable situation - the classification should remain practical after - I have which stand all preferred one large genus Ingolfiella, may for pigeon-holing all small-sized ingolfiellids, irrespective of sexual based. differences on which the subgenera are partly A number in in of names on the genus-grouplevel was already use the alternative systems of KARAMAN and RUFFO, hence only one had new subgeneric name to be proposed for the new system.