A new species of Cosmioconcha (Gastropoda : Columbellidae) from the northern Gulf of Mexico

2007·1.5 MB·

by  Emilio F Garcia

E. F.Garcia NOVAPEX 8 (2): 43-46. 10 octobre 2007
A new species of Cosmioconcha (Gastropoda: Columbellidae)
from the northern Gulf of Mexico
Emilio F. GARCIA
1 15 Oak Crest Dr,
Lafayette, LA 70503, U. S. A.
Efg21 [email protected]
KEYWORD.Gastropoda. Columbellidae. Cosmioconcha. GulfofMexico.
ABSTRACT. A new species ofCosmioconcha. dredged offthe Alabama coast. northern Gulfof
Mexico, is described and compared to its congeners. It is the smallest ofail western Atlantic
species ofCosmioconcha heretofore described.
INTRODUCTION Abbreviations
ANSP: The Academy of Natural Sciences,
The Biology Department at the University of
Philadelphia, Pennsylvania, USA.
Louisiana at Lafayette has conducted a séries of
dredging cruises in the GulfofMexico. An important USNM: National Muséum of Natural History,
Smithsonian Institution. Washington, DC, USA.
objective of thèse cruises has been to try to hâve a
EFG: author's collection
better understanding of the biodiversity of the Gulf.
dd: empty shell(s)
This objective has been largely met with the
methodical study ofthe material collected, particularly SYSTEMATICS
the micro-mollusks extracted from the sédiment. The
dredged material has brought to light many molluscan Superfamily BUCCINOIDEA Rafmesque, 1815
species previously unrecorded for that body of water Family COLUMBELLIDAE Swainson,, 1840
(see Garcia 1999b. 2000. 2002. 2003. 2007; and Subfamily ATILIINAE Cossman, 1901
Garcia & Lee 2002, 2003), as well as a number of Genus Cosmioconcha Dali, 1913
previously un-described species (see Garcia 1999a. Type species: Buccinum modestum Powys. 1835, by
2005. 2006a, 2006b). original désignation.
In the past year three new species of Cosmioconcha
from the western Atlantic hâve been described. Two Cosmioconcha nana n. sp.
of thèse species, Cosmioconcha rikae Monsecour & Figs 1-7
C
Monsecour, 2006 and geigeri Garcia, 2006, inhabit
the Gulf of Mexico. A third species. Cosmioconcha Type material. Holotype ANSP 413705; length 4.6
nitens (C. B. Adams, 1850), also inhabits the Gulf. In mm, width 2mm (Figs. 1-6), 1 paratype USNM
a cruise conducted during June-July. 2006, two empty. 2043333 (Fig. 7). 1 paratype EFG 25195.
but well- preserved shells of another species of
Cosmioconcha were obtained with a box dredge off Type locality. Northern GulfofMexico; offAlabama,
29°24.43'N, 87°58.63'W, 74-72 m.
the coast ofAlabama; and searching through material
collected in earlier cruises uncovered a third spécimen Material examined. Alabama: 29°24.43'N,
dTraekdignegdiinnto20c0o4nsoifdfértahetiLoonuitshieannaewcoasspte.cies described 87°58.63'W, 74-72 m, 2 dd (holotype (Figs. 1-6). 1
hCeorsemini,ocoancfhulal f5r0om% thoef wtehseterdnescArtilbanetdicspweicllieshâvoef 2pa8r°a3t8y.p1e6'N8(F9i°g3.3.179)')W.. 6L0o-u7i0sim.a.na1:ddS(apcakreatttypeB2a).nk,
been reported from the GulfofMexico, and more than Distribution. North-central Gulf of Mexico, off
35% will hâve been described in the very récent past. Alabama and Louisiana. 60-74 m.
Thèse facts speak for the success ofthe work that has
mm
been done in the Gulf in récent years, as well as for Description. Holotype 4.7 in length, strong.
the potential formany more future discoveries. fusiform (width/' length ratio 0.43 mm) (Figs. 1-6).
Ail cruises hâve been conducted on board the R/ V Protoconch paucispiral. of1.75 whorls, smooth, white,
"Pélican", a research vessel owned and operated by becoming rust-colored towards end oflast whorl (Fig.
LUMCON, the Louisiana Universities Marine 4). Transition between protoconch and teleoconch
Consortium.
43
i i Garcia A new species ofCosmioconcha
sharpl) tnarked b> an abrupt change in color and white protoconch. stronger axial sculpture, a différent
omamentation (Fig. 4). Teleoconcb of jusi over 3 spiral sculpture, and a milky-white band at suture.
whorls; first whorl almost flat-sided; following whorls Thèse three species are larger than Cosmioconcha
increasing in convexity, Suunv deep, channeled. Axial nana n. sp.
sculpture of few, sporadically placed, growth scars Cosmioconcha calliglypta, a southern Caribbean
(Fig. 2); one or two growth scars per whorl; species, is stouter, and lias stronger sculpture.
Qumerous, axially oriented microscopic threads give Cosmioconcha helenae, a Brazilian species, has 6
the shell surface a wrinkled appearance (Fig. 5). Spiral whorls, is axially ribbed, and is nodulose at suture.
sculpture o\' incised, punctate spiral grooves; 9 such Cosmioconcha humfreysi, a species described from
grooves on fîrsl whorl, rapidly increasing in tiumber Aruba, is more délicate, with a row of white spots
on later whorls; about 12 strong spiral cords appearing above the suture, and has 9 whorls. Cosmioconcha
at anterior end oflast whorl; cords becoming slightly dedonderi, from the southwestem Caribbean, has a
nodulose vvhen erossed by axial threads. Outer lip différent color pattern and a cancellate sculpture. Ail
strengthened by a moderately strong, wide varix (Fig. of thèse species are also larger in size than
2); omamentation of last whorl continuing over Cosmioconcha nana n. sp.
surface of varix. Aperture elongate-ovate, In his dissertation on Brazilian columbellids, Costa
approximately halfthe length ofthe shell; inner outer (2005: 152-156) describes, without naming them, two
lip showing 10 weak denticles; columella with a slight species from Brazil: Cosmioconcha "sp. 1", with axial
swelling at anterior end. followed posteriorly by a costae, is similar to C. rikae Monsecour &
sharp. conspicuous denticle (Fig. 6); otherwise Monsecour, 2006 in gênerai shape and sculpture.
smooth. Anteriorcanal short, wide. Shell colorcreamy Cosmioconcha "sp. 2" is similar in size to the new
white. with tan. squarish markings that tend to form a species; however, it is differently colored, has wider
checkered pattern at suture and at periphery of last shoulders, has a subsutural spiral sulcus, and différent
whorl. surface omamentation.
Discussion. Paratype 1 is slightly larger than the Etymology. From the Latin nanits (noun, meaning a
mm mm
holotype, measuring 5 in length and 2.1 in dwarf), in référence to the relatively small size ofthe
width. It has ail of the characters of the holotype, species when compared to its congeners. It is used
including the rust-colored coloration at the end ofthe hère as an adjective, meaning "ofsmall size."
protoconch, as well as the conspicuous denticle near
the base ofthe pariétal wall. Paratype 2, the Louisiana ACKNOWLEDGEMENTS
mm
spécimen, measures 4.2 in length but is chipped at
the anterior end. It is also slightly more eroded than My thanks to Drs. Darryl Felder and Suzanne
the Alabama spécimens; otherwise, it shows ail ofthe Fredericq, members ofthe Biology Department at the
important morphological characters and markings of University of Louisiana at Lafayette, for inviting me
the othertwo type spécimens. tojoin them on the 2006 Gulfof Mexico Cruise, and
There are seven columbellid taxa from the western to Kevin Monsecour, whose review ofthis study has
Atlantic that hâve been assigned to Cosmioconcha: C. improved its quality. The material for this study is
nitens (C. B. Adams, 1850), C. calliglypta (Dali & based upon work supported by the National Science
Simpson, 1901), C. helenae (Costa, 1983), C. Foundation underGrantNo. 0315995.
humfreyi Jong & Coomans, 1988, C. dedonderi
Monsecour & Monsecour, 2006, C. rikae Monsecour REFERENCES
& Monsecour, 2006, and C. geigeri Garcia, 2006.
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known to inhabit the GulfofMexico. représentâtes da Familia Columbellidae Swainson,
Cosmioconcha nitens has a multispiral protoconch, 1840 (Mollusca, Caenogastropoda) da costa
lacks the conspicuous columellar denticle, has a brasileira. Ph. D. Dissertation, Universidade
smooth surface except for the spiral cords at the base Fédéral do Rio deJaneiro/Museu Nacional, Rio de
of the last whorl, and has a proportionately longer Janeiro, 333 pp.
aperture; C. rikae is axially ribbed and has a nodulose Garcia, E. F. 1999a. Three new gastropod species
spiral cord anterior to the suture; and C. geigeri has a from the New World. Apex 14(3-4):59-65.
Figures 1-7
1-7. Cosmioconcha nana n. sp., offAlabama, 29°24.43'N, 87°58.63'W, 74-72 m. 1-6. Holotype ANSP 413705;
length 4.6 mm, width 2 mm; 7. Paratype 1USNM 2043333, length 5 mm.
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E.F.Garcia NOVAPEX 8 (2): 43-46, 10 octobre 2007
45
I I G \IU I \ A new speciesofCosmioconcha
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