Morrison, 1943
Rio Siapa (Caño Casiquaire- Rio Negro Dr.)
Territorio Federal Amazonas, Venezuela.
Original Description: Diplodon flucki Morrison, J.P.E. 1943. Two new Orinoco unionids, with notes on Unio granadensis Lea and U. patulus Lea. Nautilus. 57(1):14-16 + 2 plates.
Type Locality: Orinoco River, above Munduapo, [Amazonas] Venezuela.
Holotype: USNM 521998.
Paratypes: USNM 521999 (2). MCZ 167994 (4).
Synonymy:
- Diplodon (Diplodon) flucki Morrison, 1943
- Haas 1966:518.
Diplodon flucki Morrison, 1943
- Parodiz 1968:5.
Description: “Shell of medium size, subsolid, elongate-rhomboid to long elliptical, inflated; posterior ridge rounded or biangulate, ending posteriorly in a biangualte point a little above the base line; anterior end regularly rounded; dorsal line slightly arched; ventral margin slightly curved; the posterior end obliquely truncate, meeting the base line at the post basal biangulation; epidermis olivaceous. Beaks little inflated, radially sculptured with very delicate, pinched up ridges, minute and curved downward anteriorly, more distant and straight medially, and striking divaricate at a 45 degree angle just above the posterior ridge posteriorly; the beak sculpture extends only over the umbonal portion of the shell, up to a length of about 15 mm. Sculpture finely concentrically striate, with minute traces of of radially sculpture over the disc. Hinge teeth distinctive, the hinge line narrow, pseudocardinals lameller, compressed, two in each valve, the (upper) anterior one in the right valve small, thin, low; the posterior long, high, and triangular; the anterior one in the left valve low, long, and triangular; the posterior high, triangular, being practically a portion of the interdentum. The two high triangular posterior pseudocardinals fit into depressions in the hinge line opposite, so that the ventral aspect of the hinge line is zigzag in this part. Nacre white, beautifully iridescent; the cicatrices are moderately deep, the posterior confluent, the anterior deeper, with the anterior retractor a deep, distinct pit on the bottom of the pseudocardinal buttress. Dorsal muscle scars are plainly marked in a diagonal row in the middle of the shallow cavities of the beaks.
The holotype, USNM 521998, was collected from the Orinoco River above Mundapo, Venezuela, and measures: Length, 52.3 mm., height 28.3 mm., diameter, 22.6 mm. One of two paratypes, USNM. No. 521999 exhibits almost perfect (uneroded) beak sculpture; it is a young shell only 26 mm. in length.
The finely concentrically striate sculpture, with traces of radial sculpture, and the peculiarly zigzag hinge line produced by the meshing of the thin, high, triangular pseudocardinals, indicate a relationship with D. suavidicus (Lea) from the Amazon Basin. It differs from that species in being more elongate, a little more inflated, and more pointed behind. The beak sculpture of D. flucki (fig. 5) differs from that of D. suavidicus in the straightness of the medial ridges, not converging; and the more definitely clean-cut divaricate wrinkles on the posterior slope; also, the fine anterior riblets are straight in suavidicus, regularly curved downward in flucki.” (Morrison, 1943:14-15).
Range: Upper Orinoco River in Venezuela and Colombia.
Comments: This is one of only three species of Diplodon known from the Orinoco River drainage (one undescribed). Only seven specimens of D. flucki are known (all are types). It is known only from a short stretch of the Orinoco River proper in Amazonas, Venezuela. This is a remote part of Venezuela, and very little mollusk collecting has been done in this part of the world. Parodiz (1968:5) stated that D. flucki was related to D. suavidicus (=rhombeus) from the Amazon River, Brazil, but that it was larger, elongated, and more solid. He also stated that this is a “northernmost isolated species”.
Specimens Examined: USNM 521998 (Holotype). Orinoco River, above Munduapo, [Amazonas], Venezuela [5 February 1899]. [G.K. Cherrie]. MCZ 167994 (4 Paratopotypes). Orinoco River, above Munduapo, [Amazonas], Venezuela. 5 February 1899. G.K. Cherrie. USNM 521999 (2 Paratypes). Orinoco River, Maipures, [Amazonas], Colombia [Venezuela]. [March], [1899]. [G.K. Cherrie].
Other Diplodontini in the area. Diplodon pazi (Hildago, 1868). Range: Imbabura, Ecuador. Diplodon suavidicus (Lea, 1856). Range: Amazon.
Literature Cited
Adams H, Adams A. 1858. The genera of recent Mollusca, arranged according to their organization. 3 vols. https://doi.org/10.5962/bhl.title.4772.
Baker HB. 1930. The Mollusca collected by the University of Michigan-Williamson Expedition in Venezuela. VI. Occasional Papers of the Museum of Zoology, University of Michigan. No. 210. 1-81 + 7 plates.
Bruguiere JG. 1792. Choix de memoires sur divers objets ‘histoire naturelle formant las collections du Journal d’Histoire Naturelle, I, p. 131.
D’Orbigny A. 1835. Synopsis terrestrium et fluviatilium molluscorum, In suo per Americam meridionalem itinere, ab. A. d’Orbigny, collectorum. Magasin de Zoologie. 6(61/62):1-44.
Dunker W. 1858. Einige neue species der Naiaden. Mal Blatt. ?:225-229.
Ernst A. 1876. Enumeracion sistematica de las especies de moluscos terrestres y de aqua dulce, halladas hasta ahora en los alrededores de Caracas y demas partes de la republica. pp. 225-230 in Estudois sobre la flora and fauna de Venezuela.
Gray JE. 1847. A list of the genera of recent Mollusca, etc. Proceedings of the Zoological Society of London XV:129-214.
Haas F. 1931. Versuch einer kritischen sichtung der Südamerikanischen Najaden. Senckenbergiana 30(2):87.
Haas F. 1966. Superfamilia Unionacea. Das Tierreich (Berlin). 88:x + 663 pp. https://doi.org/10.1515/9783111721569.
Johnson RI. 1979. The types of Unionacea (Mollusca: Bivalvia) in the Museum of Zoology, the University of Michigan. Malacological Review 12(1-2):29-36.
Lamarck JB. 1819. Histoire Naturelle des Animaux sans Vertebres. ?? pp. https://doi.org/10.5962/bhl.title.12712.
Lea I. 1870. Synopsis of the Family Unionidae. 4th Edition, very greatly enlarged and improved. Henry C. Lea, Philadelphia. 184 pp. https://doi.org/10.5962/bhl.title.46363.
Lea I. 1871. Description of three new species of exotic Unionidae. Proceedings of the Academy of Natural Sciences of Philadelphia 1871:188.
Lea I. 1874a. Journal of the Academy of Natural Sciences of Philadelphia Vol. VIII. ?? pp.
Lea I. 1874b. Observations on the genus Unio. XIII. ?? pp. https://doi.org/10.5962/bhl.title.11214.
Marshall WB. 1922. New pearly fresh water mussels from South America. Proceedings of the United States National Museum. 61(16):1-9 + 3 plates. https://doi.org/10.5479/si.00963801.61-2437.1.
Marshall WB. 1926. New land and fresh-water mollusks from Central and South America. Proceedings of the United States National Museum. 69(12):1-12 + 3 plates. https://doi.org/10.5479/si.00963801.69-2638.1.
Marshall WB. 1927. A new genus and two new species of South American fresh-water mussels. Proceedings of the United States National Museum. 71(6):1-4 + 2 plates. https://doi.org/10.5479/si.00963801.71-2678.1.
Marshall WB. 1930. Type of Anodontites Bruguière. Nautilus 43(4)128-130.
Marshall WB. 1931. Ruganodontites, a new subgenus of South American pearly, fresh-water mussels. Nautilus 45(1):16-20.
Gronovius LT. 1781. Zoophylacium Gronovianum, etc. p. 260. https://doi.org/10.5962/bhl.title.115893.
Modell H. 1942. Das naturliche system der Najaden. Arch. fur Mollusk. 74:161-191.
Morrison JPE. 1943. Two new Orinoco unionids, with notes on Unio granadensis Lea and U. patulus Lea. Nautilus. 57(1):14-16 + 2 plates.
Olsson AA, Wurtz CB. 1951. New Columbian naiades, with observations on other species. Notulae Nature 239:1-9.
Parodiz JJ, Bonnetto AA. 1962. Taxonomy and zoogeographic relationships of the South American Naiades (Pelecypoda: Unionacea and Mutelacea). Malacologia 1(2):179-213.
Pilsbry HA, Olsson AA. 1944. A Venezuelan species of Fossula. Nautilus. 57(3):89, plate 10.
Rochebrune AT. de. 1881. Sur Quelques especes du Haut-Senegal. Bull. Soc. Pilom. 33-35.
Schumacher FC. 1817. Essai d’un nouveau système des habitations des vers Testaces. Copenhagen 1-287 + 22 plates. https://doi.org/10.5962/bhl.title.35863.
Simpson CT. 1900. Synopsis of the naiades, or pearly fresh-water mussels. Proceedings of the United States National Museum. 22(1205):501-1044. https://doi.org/10.5479/si.00963801.22-1205.501.
Simpson CT. 1914. A descriptive catalogue of the naiades, or pearly fresh-water mussels. Parts I-II. Bryant Walker, Detroit, Michigan. xii + 1540 pp. https://doi.org/10.5962/bhl.title.10910.
Sowerby GB. 1869. Mongraph of the genus Mycetopus. in L. Reeve and G.B. Sowerby (eds.) Conchologica Iconica., 20 vols., 2,727 colored plates. Completed by Sowerby. Unios in XVI, Anodontas in XVII. https://doi.org/10.5962/bhl.title.8129.
Spix JB, Wagner JA. 1827. Testacea fluviatilia quae in itinere per Brasiliam collegit. Leipzig. pp. 1-36. https://doi.org/10.5962/bhl.title.59807.
Swainson W. 1840. A treatise on Malacology. London. ?? pp. https://doi.org/10.5962/bhl.title.8027.
von Martens E. 1873. Die Binnenmollusken Venezuelas, etc. Festschrift Gesell. Nat Freunde. pp. 157-225 + 2 plates. https://doi.org/10.5962/bhl.title.10052.
von Martens E. 1900. Biologia Centrali-Americana. Zoologia, Mollusca. ?? pp. https://doi.org/10.5962/bhl.title.730.