During research in coastal marshes of the Mississippi Delta region in 1975, a large, undescribed amphipod belonging to the genus Cerapus was discovered in tidal channels. This new species, C. benthophilus, is characterized by its large size and 7-12 segmented antennal flagella. Habitat preference is muddy silt bottoms upon which it constructs conspicuous mats or  tufts  of interwoven tubes in shallow coastal bays and marshes from Louisiana to the panhandle areas of northern Florida

Heard, Richard W.

Thomas, James Darwin

Thomas, James Darwin.

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A New Species Of Cerapus Say, 1817 (Crustacea: Amphipoda) From The Northern Gulf Of Mexico, With Notes On Its Ecology

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Nova Southeastern UniversityNSUWorksOceanography Faculty Articles Department of Marine and Environmental Sciences1-1-1979A New Species of Cerapus Say, 1817 (Crustacea:Amphipoda) from the Northern Gulf of Mexico,with Notes on its EcologyJames Darwin ThomasReef Foundation, thomasjd@nova.eduRichard W. HeardDauphin Island Sea LabFind out more information about Nova Southeastern University and the Oceanographic Center.Follow this and additional works at: http://nsuworks.nova.edu/occ_facarticlesPart of the Marine Biology Commons, and the Oceanography and Atmospheric Sciences andMeteorology CommonsThis Article is brought to you for free and open access by the Department of Marine and Environmental Sciences at NSUWorks. It has been acceptedfor inclusion in Oceanography Faculty Articles by an authorized administrator of NSUWorks. For more information, please contactnsuworks@nova.edu.NSUWorks CitationJames Darwin Thomas and Richard W. Heard. 1979. A New Species of Cerapus Say, 1817 (Crustacea: Amphipoda) from the NorthernGulf of Mexico, with Notes on its Ecology .Proceedings of the Biological Society of Washington , (1) : 98 -105.http://nsuworks.nova.edu/occ_facarticles/610.PROC. BIOL. soc. WASH. 92(1), 1979, pp. 98-105 A NEW SPECIES OF CERAPUS SAY, 1817 (CRUSTACEA: AMPHIPODA) FROM THE NORTHERN GULF OF MEXICO , WITH NOTES ON ITS ECOLOGY James D. Thomas and Richard W. Heard Abstract . During research in coastal marshes of the Mississippi Delta region in 1975 , a large , undescribed amphipod belonging to the genus Cer-apus was discovered in tidal channels . This new species, C. benthophilus , is characterized by its large size and 7 -12 segmented antennal flagella. Hab-itat preference is muddy silt bottoms upon which it constructs conspicuous mats or " tufts" of interwoven tubes in shallow coastal bays and marshes from Louisiana to the panhandle areas of northern Florida. Cerapus benthophilus , sp. nov . Figs . 1-4 Holotype. USNM 171350, male (10 mm BL) , Ocean Springs , Mississip-pi , 300 23 '36''N ; 88°48 '31 "W; Davis Bayou , 400 m west of the Gulf Coast Research Lab, 1.5 m depth , collected by R. Heard , 8 April 1976. Paratypes . USNM 171351 , 29°13'01"N; 900 14'05''W; Bayou Sevin , Lou-is iana, 3 m depth , collected by J. Thomas, 14 March 1975. Diagnosis . Species large , male and female reaching body lengths , ex-cluding antennae, of I I and 9 mm respectively ; pereon segment I of male bearing lateral keel; antennal flagella 7-12 segmented ; basis of pereopod 2, anterodorsal margin with numerous, long setae (males only). Description. Male , 10 mm. Body: Constricted between pereon seg-ments I and 2; head elongate, equal in length to pereonites 1-2. Rostrum: Reaching ocular margin ; frontal ocular margin incised , lateral lobes promi-nent. Eyes: Circular; black in formaldehyde-preserved specimens . Antenna I: 60% BL; reaching firs t flagellar segment antenna 2: segment I compressed laterally , deepest posteriorly , bearing paired setae ventrally ; peduncle with numerous , paired , long setae; flagellum 9-segmented . Antenna 2: 90% BL; flage llu m 9-segmented; peduncle wi th long , paired setae . Upper lip : Apical margin sl ightly emarginate. Mandible: Normal for genus; palp segment I the shortes t; incisors moderate ly toothed; lacina mobili s followed posteriorl y by 3 raker spi nes ; molar strongly triturative . Lower lip: Mandibular projec- I tion pointed . Max illa I: Inner plate small , bearing single apical seta; outer plate with 9- 10 apical spines; palp 2-segmented , medial and lateral margins bare . Maxilla 2: Inner and outer plates lightl y fringed with setae mediall y. VOLUME 92, NUMBER I I I , , 01) ,-> o • o V) ,.., -::0 z ell ;:J • E E o -• " -;;; E • " 0. C o -o .<: .. 0. o f-• ,-0. 0. ,-> 8 • • > o c , ::0 ",Z "'ell ~;:J ... . " E U E • -.0 - • , " 01)-,- " u.. E .:U 99 100 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON a c b •• 0.2 mm I I (except f) d e f h 9 Fig. 2. Cerapus bellthophi/us, sp. nov . Male; b, d; female; a, c, e , f, g , h. a, maxilla I: b, maxilla 2; c, maxilliped; d, distal portion lower lip ; e, mandible; f, inci sors; g, lower lip ; h, upper lip. I I VOLUME 92 , NUMBER I 101 inner plate with oblique facial row of setae. Maxilliped: Inner plate fringed with setae; outer plate with 10-12 spine teeth on inner margin; palp seg-ments I and 2, outer margins bare. Coxae: 1-7 separated serially; coxae 3 and 4 bilobed and produced anteroventrally; coxa 5 the largest, anterior margin deeply rounded; coxal gills present on coxae 3-5, 4 the largest. Gnathopod I: Articles 5 and 6 subequal. Gnathopod 2: Complexly subche-late, much larger than pereopod 1; basis with anterodorsal margin bearing numerous long setae; palm strong, anterodistal margin produced as promi-nent tooth. Pereopod 5: Article 4 bilobed, posterior lobe with 7-9 setae; article 7 with two small hooks. Pleopods: Unequal; 1 the largest, basal segment of outer ramus broadened; inner ramus 70% of outer ramus. PI eo-pod 2: 90% of pleopod 1; inner ramus 90% of outer ramus. Pleopod 3: 60% of pleopod I; inner ramus 60% of outer ramus. Uropod 1: Biramous; outer ramus with terminal sensory setal bundle surrounded by circular cup of large, triangular spines; inner ramus reaching 65% of outer, sensory setal bundle present. Uropod 2: Uniramous; reaching end of peduncle uropod I. Uropod 3: Uniramous; tip with medial hooks. Telson: Fleshy ; bilobed , each lobe with double row of distal spines. Female. As male except in following characters: Antenna 1 90% of antenna 2; antenna 2, 50% BL; flagellar articles 7 (rare) to 9, usually 8; pereonite segment 1 lacking lateral keel: body generally thicker, not attenuated between pereonite 1 and 2; coxae 3 and 4 not deeply bilobed; pereopods 1 and 2 subequal; basis of pereopod 2 sparsely setose; brood plates present on segments 2-5, 5 the largest; brood setae simple; lower lip lacking pointed mandibular projection. Distribution. Cerapus benthophilus is presently known from coastal marshes in Louisiana (Thomas, 1976), Mississippi , and Florida. There are no records of C. benthophilus from the Atlantic Coast. Etymology. The specific name refers to the habit of this species in con-structing large masses of tubes on the bottom in contrast to the short, port-able tube typical of this genus. Discussion. While Cerapus benthophilus is unique in the genus because of its large size, multisegmented flagella , and lateral keel , there exists con-siderable confusion among other members of the genus . The taxonomy of Cerapus is based , in part, on the number of flagellar articles and in Say's (1817) original description of the genus (Cerapus tubularis) no mention was made concerning flagellar articles. The resulting practice of authors restrict-ing certain species on the basis of flagellar articles alone has caused con-fusion in the placement of species. Barnard (1962) attempted a revision of Cerapus but in light of new species being described a thorough revision is needed. Barnard (1973) has also removed Cerapus from Corophiidae and placed it in the Ischyroceridae. \----------~-------------------102 a c d PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON b f e E E E E LD LD • • o 0 ( b ,d) (a,c,e) Fig. 3. Cerapus benthopililus. sp. nov. Male ; a , d; female ; b. c, e , f. a, gnathopod I; b, gnathopod I; c , gnath opod 2; ct , gnathopod 2; e, pereopod 5; r, pereopod 5, segment 7. VOLUME 92, NUMBER I b d c e 0.1 mm f 9 , 0.5 mm , E E -• o , a , 0.5mm 103 0.5mm , h , Fig. 4. Cerapus benthophilus, sp. nov. Male. a, urosome; b, uropod I; c, uropod 3; d, telson; e, uropod 2; f, pi eo pod I ; g, pleopod 2; h, pleopod 3. 104 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON Comparisons . C. benthophilus is distinguished from all other adult species of Cerapus in having more than 6 articles in the antennal flagella. Flagellar articles are variable, ranging from 7 in adult females (5 mm) to 12 in adult males. Adult males of C. benthophilus usually exhibit 9-10 flagellar articles. Extremely large males (13 mm) have been noted with 12 flagellar articles but these individuals are rare and not considered typical. Specimens exhibiting at least 7 flagellar articles averaged 6 mm in body length. Juveniles (3 mm) had at least 4 and 6 flagellar articles on antennae 1 and 2 respectively. The large size of C. benthophilus adults also distinguishes them from other members of the genus which are generally smaller (3-5 mm, adult males). Other diagnostic features of C. benthophilus include the lateral keel on pereon segment 1 and the setose condition of the basis of pereopod 2 (both conditions exhibited by adult males only). Ecological notes. In the Barataria Bay, Louisiana, region, Thomas found C. benthophilus abundant on muddy silt bottoms subject to current flow. Extensive mats of interwoven tubes of C. benthophilus (up to 15 cm across) dominated the bottom in many low and intermediate salinity areas (\-15%0). Another abundant amphipod occurring in the vicinity of C. ben-thophilus was Ampelisca abdita Mills. A. abdita was found on muddy bot-toms in areas of little or no current influence, such as channel margins and protected bays. In transitional areas where Cerapus and Ampe/isca overlap, the firm, erect tubes of C. benthophilus are easily distinguished from the thin, flexible tubes of Ampelisca. The possibility of amphipod tubes as a potential high-protein food source for juvenile and adult brown shrimp Penaeus aztecus Ives, in the Barataria Bay region was discussed by Jones (1973). The extensive coverage of C. benthophilus and A. abdita tubes in coastal marsh systems of the Northern Gulf of Mexico may represent a heretofore unrealized food source and should be investigated. Acknowledgments The authors wish to thank Dr. E. L. Bousfield for critical review of portions of the manuscript. The artistic skills of Linda Lutz, Dauphin Island SeaLab, are greatly appreciated. This research is supported by the National Science Foundation, Grant #DEB77-15883. Literature Cited Barnard , J . L. 1962. Benthic marine Amphipoda of Southern California: Families Aoridae. Photidae, Ischyroceridae , Corophiidae . Podoceridae.-Pacific Nat. 3: 1-72. --. 1973. Revision of Corophiidae and related families (Amphipoda) .-Smithson. ContI'. Zoo!. 15 1: 1-27. Jones, R. R. 1973. Utilization of Loui siana estuarine sediments as a source of nutrition for the brown shrimp Pellaeus aZ/a'us Ives .-Ph.D. Dissertation , La . State Univ ., Baton Rouge . VOLUME 92 , NUMBER I 105 Say, T. 181 7. On a new genus of Crustacea , and the species on which it was established.-J. Acad. Nat. Sci., Philadelphia 1:49-52. Thomas , J . D. 1976. A survey of gammarid amphipods of the Barataria Bay, Louisiana , region.-Cont. Mar. Sci. 20:87-100. (JDT) Newfound Harbor Marine Institute , Big Pine Key , Florida 33043; (RWH) Dauphin Island Sea Lab , Box 386, Dauphin Island, Alabama 36528. 

A New Species of Cerapus Say, 1817 (Crustacea: Amphipoda) from the Northern Gulf of Mexico, with Notes on its Ecology

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A New Species of Cerapus Say, 1817 (Crustacea: Amphipoda) from the Northern Gulf of Mexico, with Notes on its Ecology

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