Papers by Richard Jacobsen
EUROPEAN JOURNAL OF ENVIRONMENTAL SCIENCES, 2015
Smittia denotata sp. nov. is described from adult males collected during winter months from two G... more Smittia denotata sp. nov. is described from adult males collected during winter months from two Georgia locations. The immature stages and female are unknown. The species is readily recognizable by the distinctive long, basally microtrichose, tapered anal point with rounded apex, virga consisting of two separate spine clusters, and gonostylus with crista dorsalis and curved outer thorn-like projection.
Scientific Investigations Report, 2008
Aquat Ecol, 1992
The larvae of four species of Epoicocladius from eastem North America are described along with a ... more The larvae of four species of Epoicocladius from eastem North America are described along with a redescription of the European species, Epoicocladius ephemerae (Kieffer). A key to known 4th instar Nearctic and western Palaearctic Epoicocladius larvae is presented. Previous species descriptions and records of Nearctic Epoicocladius spp. are discussed in reference to the larvae described here. I-arvae of Epoicocladius ephemerae (Kieff.), a species described from Europe which is currently sJrnonymized with the Nearctic E. flavens, have yet to be collected in North America. This suggests that the synonymy is invalid and E. ephemerae should be considered a legitimate species. A likely candidate to be the larva of Epoicocladius flavens (Malloch) is suggested. However, until reared adults are obtained, the larva of E. flavens remains unknown.
Everglades midge community composition is strongly dependent upon hydroperiod (HP) and water qual... more Everglades midge community composition is strongly dependent upon hydroperiod (HP) and water quality. Longer HPs are generally associated with higher alpha diversity, species density, and total species richness. However, the development of extensive calcareous periphyton growth in marshes with 4-10 month HPs strongly influences community structure, and diversity and richness measures show no change along marl prairie HP gradients. Increases in species density with hydroperiod represent increases in habitat volume and productivity, not changes in community structure. Beta diversity is greatest when transitioning from marshes with 7-10 month HPs to those with >10 month HPs. At these HP lengths / water depths, plant communities that permit extensive periphyton growth are replaced by plant communities that inhibit periphyton growth, enable more organic soil development, and provide habitat for more specialized species. Point-source nutrient enrichment produces strong shifts in Evergl...
conference.ifas.ufl.edu
... Ph.D. Dissertation, Duke University, 356 pp. King, RS and CJ Richardson. 2002. Evaluating sub... more ... Ph.D. Dissertation, Duke University, 356 pp. King, RS and CJ Richardson. 2002. Evaluating subsampling approaches and macroinvertebrate taxonomic resolution for wetland bioassessment. JNABS 21:150-171. Lindegaard, C. 1995. Classification of water-bodies and pollution. ...
Journal of the North American Benthological Society, 2002
Manoa pahayokeensis n. sp. is described from, and diagnoses are provided for, adults, pupal exuvi... more Manoa pahayokeensis n. sp. is described from, and diagnoses are provided for, adults, pupal exuviae, and presumptive larvae collected from the Taylor Slough and Chekika areas of Everglades National Park, Florida. The generic description of Manoa is emended to accommodate M. pahayokeensis. Diagnostic autapomorphic character states for the genus include: for females, the medially divided floor under the vagina; for pupae, the elongate thoracic horn with characteristic tracheation, and the spine-like taeniae on the anal lobes; and for larvae, the stout, posteriorly curved procerci that arise close together from a posteromedian tubercle. Our collections are the first record of this rarely encountered tropical genus in North America and highlight the tropical component of the Everglades chironomid fauna. All specimens were collected from shallow-water marsh sites subject to water-level fluctuation and seasonal drying. Collection records for Manoa suggest the genus originated in Gondwanaland and arrived in the Nearctic either by northerly dispersal from South America or by tectonic vicariance events and dispersal from Africa.
Aquatic Insects, 2003
JACOBSEN: Taxonorny ol' thc Gcnus I'lrtt.vsmirtiu S:cthcr (I)iptcra: Chir6n.rnrclac). with Cornrn... more JACOBSEN: Taxonorny ol' thc Gcnus I'lrtt.vsmirtiu S:cthcr (I)iptcra: Chir6n.rnrclac). with Cornrncnts on its llcokrgy and lrhylogcnctic position. Aquatic Insccts, Volunrc 20 (I998), No_ 2. pp. Diagnoscs arc providcd lilr thc larva and pupa of Pltttt,sntirtitt lirr thc I'irst tirnc. I)cscripti0ns trl thc trralc and lcrnalc ol' I'. bitf i antl thc rnalc olt P. .lintbriutu ur.c cmcndcd t. irrcludc Iratcrial l'rom Maryland altd Pcnnsylvattia. Spccil'ic dcscriptiorrs and diirgn6scs arc prcscrtcrl lirrthclarvaandpupaorp.biryii andthclaiva,pupa,andrcnrarcoI r,..fintrtrittttt.[-"rvu",,r' lhc.gcnus appcar to inhabit prirrarily intcrrrittont strcrrns jn lirrcstcd watcrshcds. Thc rarvrc and pup:tc ol' I'lul.t"vntiltiu indicalc_1hal lhc gcnrrs bclongs within thc cladc c6rnprisctl .l lhc H?t(rotrissocludius' I'urukicllcriclltt and (.urdiotlrtdiu.igroups plus l,silontt'rrir)t.rratirrl.r, irr(l is prohably In<rst cftrsely rclatcd to rl'tc Hctcrotris,soclulii.s,qrot.tp itld l,.silrtntctrilt.rcnrtt.s.
Annales de Limnologie - International Journal of Limnology, 1995
Patterns of leaf colonization by Chironomidae were compared on three leaf substrates differing in... more Patterns of leaf colonization by Chironomidae were compared on three leaf substrates differing in rate of processing and palatability for detritivores. Each leaf species was colonized by a similar number of taxa, with Orthocladiinae and Tanytarsini comprising the dominant groups. However, the chironomid assemblage, categorized by functional feeding groups, differed greatly between the three leaf types. Black cherry leaves supported a much higher proportion of shredders (e.g. Brillia flavifrons) than either red maple or American beech packs. In contrast, beech and maple leaf packs were colonized by distinctly higher proportions of gathering-collectors (e.g. Corynoneura spp., Parametriocnemus sp., Stilocladius spp., Constempellina spp., Micropsectra spp.). Overall, the cherry packs supported a significantly higher shredder and gathering-collector biomass per g leaf pack than either the maple or beech leaves. We conclude that (1) shredders were preferentially associated with cherry leaf packs due to its higher palatability compared to the maple and beech leaves, and (2) similar colonization patterns exhibited by gathering-collectors on all three leaf species were the result of a supply of similar-quality fine detritus. Colonisation par les Chironomidae (Insecta, Diptera) de trois types de substrats foliaires dans une rivière des Appalaches .
Journal of Limnology
A new species of Heterotrissocladius is described from headwaters of two small Georgia streams, b... more A new species of Heterotrissocladius is described from headwaters of two small Georgia streams, below the Fall Line in the Coastal Plain Physiologic Province, Atlantic Slope drainage. One stream is near the coast (Lower Coastal Plain) and characterized as a "blackwater" stream due to high tannin concentrations. The other stream is inland (Upper Coastal Plain), clear and not noticeably affected by tannins. The description is based on adult males, pharate male pupae and one attached larval skin. The new species is assignable to the H. marcidus species group with some exceptions. Males differ from the previous group by a reduced number of rather weak, short acrostichal setae (0-3, previously considered as typical of the subpilosus group) as well as by a very recuded wing squamal fringe compared to most members of the H. marcidus group. Males are recognizable by an elongate, thin virga, distinctive anal point and inflated/triangular gonostylus. The female is not describ...
The larval and pupal exuviae of Chasmatonotus unimaculatus Loew were collected from soil samples ... more The larval and pupal exuviae of Chasmatonotus unimaculatus Loew were collected from soil samples from which two adult males emerged. The collection site was located in the Hocking Hills area of southwestern Hocking County, Ohio within the relatively sheltered, cool, and moist conditions of a wooded ravine which has a spring fed stream flowing through it. The soil inhabited by the immature stages was damp, but not wet, and appeared spongy with high humus content mixed with sand. The immature stages are described. Pupae can be distinguished from other genera by having the combination of a short lobe shaped thoracic horn, an enlarged antepronotum, the abdominal tergites II-VIII are completely covered by strong spines, and the anal lobe is without setation. The larvae share several morphological characters with other terrestrial taxa such as mentum with reduced number of teeth (9), anterior parapods fused, procercus absent, anal setae absent, and posterior parapods reduced. Larvae can be distinguished from other genera by having the above combination of characters in addition to not having a pecten epipharyngis and having simple labral SI. This is the first description of the immature stages for the genus Chasmatonotus.
Smittia denotata sp. nov. is described from adult males collected during winter months from two G... more Smittia denotata sp. nov. is described from adult males collected during winter months from two Georgia locations. The immature stages and female are unknown. The species is readily recognizable by the distinctive long, basally microtrichose, tapered anal point with rounded apex, virga consisting of two separate spine clusters, and gonostylus with crista dorsalis and curved outer thorn-like projection.
The larvae of four species of Epoicocladius from eastem North America are described along... more The larvae of four species of Epoicocladius from eastem North America are described along with a redescription of the European species, Epoicocladius ephemerae (Kieffer). A key to known 4th instar Nearctic and western Palaearctic Epoicocladius larvae is presented. Previous species descriptions and records of Nearctic Epoicocladius spp. are discussed in reference to the larvae described here. Iarvae of Epoicocladius ephemerae (Kieff.), a species described from Europe which is currently sJrnonymized with the Nearctic E. flavens, have yet to be collected in North America. This suggests that the synonymy is invalid and E. ephemerae should be considered a legitimate species. A likely candidate to be the larva of Epoicocladius flavens (Malloch) is suggested. However, until reared adults are obtained, the larva of E. flavens remains unknown.
AN updated list of all known chironomid-mayfly associations is presented, New unpublished, recent... more AN updated list of all known chironomid-mayfly associations is presented, New unpublished, recently published, and other associations not reported in Arvy and Peters (1976) are discussed, particularly those from the Nearctic. Sixty different chironomid-mayfly associations involving 24-26 chironomid species are currently known worldwide. The discovery of parasitic species of Epoicocladius and Nanocladius (Plecopteracoluthus) indicate that at least some parasitic Orthocladiinae may have evolved from commensal ancestors
Aspects of the symbiotic relationship of a species of Nanocladius (Plecopteracoluthus) associated... more Aspects of the symbiotic relationship of a species of Nanocladius (Plecopteracoluthus) associated with mayfly nymphs in a mountain stream in Arizona are described including its prevalence on three host species, infestation pattern, attachment site selection, and feeding behavior. N. (P.) sp. 2 is parasitic on nymphs of Thraulodes sp. Choroterpes sp, and Leucrocuta sp. as evidenced by larval gut contents and the presence of scarring on their hosts.
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Papers by Richard Jacobsen