Search

Rice seedlings of different stages of development were infested with tadpole shrimp (TPS, Triops longicaudatus [LeConte]), of different sizes in four experiments conducted in a lath house in Colusa, CA, during 2015 and 2016. Tadpole shrimp size was based on carapace length. Rice seedling stages were classified as S0 if no structures were present; S1 if only the coleoptile was present; S2 if the coleoptile and radicle were present; S3-I if the prophyll had emerged; S3-II if the first true leave had emerged but was not unfurled; and V1 if the first true leave was unfurled. Results showed that TPS of all sizes are capable of injuring rice and reducing seedling establishment, with larger TPS causing more seedling establishment reduction than medium or small TPS. The coleoptile, radicle, and roots were the structures most injured by TPS. During the S0 stage, TPS buried seeds, preventing their establishment. Seedling stages S1, S2, and S3-I were found to have the highest risk of injury by TPS, while seedling stage V1 had the lowest. Pearson's correlation between injured seedlings and the normalized number of established seedlings indicates that injury to the coleoptile, root, and radicle combined are the most important in preventing seedling establishment. [ABSTRACT FROM AUTHOR]

The large branchiopod crustaceans (Anostraca, Notostraca, and Spinicaudata) of Qatar have only been examined recently. Although 15 nominal species have been reported for the Arabian Peninsula, there is confusion surrounding the determinations of previously collected taxa from Qatar, and the validity of some spinicaudatan taxa is in question. Most spinicaudatan clam shrimp taxa are poorly described; some lack type material or the type material has been lost. We provide a review of the taxa from Qatar and some records from adjacent Saudi Arabia. We recognise five large branchiopod crustacean taxa from Qatar (two anostracans, one notostracan, and two spinicaudatans) and provide new locality records from Umm Alshkoot and correct some previous literature statements. In addition, we comment on the likelihood of another ten taxa to occur in or near Qatar. [ABSTRACT FROM AUTHOR]

The tadpole shrimp (Triops longicaudatus (Leconte); Notostraca; Triopsidae) is a vernal pool crustacean that has emerged as a significant pest for many rice farmers in California. Currently, lambda-cyhalothrin is the commercial standard and sole management practice forTPS, but resistance appears to be emerging. Field and laboratory trials were conducted from 2015 to 2018 at the Rice Experiment Station in Biggs, California, and in greenhouses at the University of California (UC) Davis to evaluate the efficacy of several alternative chemical controls and to explore early indicators ofTPS activity and damage as monitoring tools.TPS mortality in plots treated with azadirachtin was not significantly different from those in the untreated control across all trials. Copper sulfate, lambda-cyhalothrin, and clothianidin were consistently effective across both lab and field trials. Chlorantraniliprole generated effective control in four of the five trials, whereas two diflubenzuron rates generated adequate control in the field, but not in laboratory bioassays.Thus, there appear to be several effective alternative control options available for farmers, should resistance to lambda-cyhalothrin continue to spread. Water turbidity (measured using a scale of 1–4) and the number of dislodged seedlings were both significantly correlated with TPS counts in field studies. Turbidity exhibited the highest correlations with TPS counts, suggesting that with further refinement it could play a valuable role in monitoringTPS populations. [ABSTRACT FROM AUTHOR]

The large branchiopod crustacean fauna (fairy shrimp, tadpole shrimp and clam shrimp) of the Neotropical Bioregion are incompletely known, with scattered records for many taxa, and many new taxa discovered and described regularly. As an aid to furthering our knowledge of the group in this region, we present an assortment of notes and records on various Neotropical taxa. We present our information in the form of a checklist, listing all reported species, with a review of their known distribution, with 56 new distributional records for 29 taxa. We also include a revised description of Spiralifrons mira based on new material from Brazil, and provide important comments on the Leptestheriidae, reducing Strakrabiidae, Straskrabia, and Brtekia to synonymy. The information presented here will assist in additional studies, surveys, and conservation, as well as help develop a biogeographical understanding of this vast region. Thus, we have compiled these records so that it will be available to other researchers. Future survey efforts will undoubtedly reveal additional records and taxa. [ABSTRACT FROM AUTHOR]

Large branchiopod crustaceans are among the most threatened freshwater invertebrates of the world. They are regarded as a flagship group in the conservation of temporary waters, and knowledge of their ecology and conservation has developed rapidly in recent years, especially in the Mediterranean region. Little is known, however, about population functioning in species associated with vernal pools in cooler temperate areas, despite recent data showing a significant decline in their localities. The present study was conducted in western Poland, on a cluster of vernal pools known to host a Central European diversity hotspot of large branchiopods. We collected data on water and sediment quality, as well as hydroperiod length, to determine their effect on the occurrence of four large branchiopod species present in the ponds during our samplings: Eubranchipus grubii (Anostraca), Lynceus brachyurus (Laevicaudata), Cyzicus tetracerus (Spinicaudata) and Lepidurus apus (Notostraca). According to the statistical analyses, the presence or absence of particular species was affected by hydroperiod length, heavy metal content in the sediments of the marginal zone of the pond, total water phosphorus content, and pH value. Since previous studies show that deep and relatively small kettle-hole ponds seem to be the most vulnerable to human-induced changes in water nutrient contents and acidification, large branchiopod populations of this type of pools should be the first target for monitoring and active forms of protection, with the aim of maintaining the good water quality. Shallow shore-bursting type ponds are subject to increased heavy metal contamination and require activities reducing the influx of these elements from their agricultural catchment. Possible forms of protection are suggested, and the use of large branchiopods as an umbrella group in temporary waters of temperate climate is also discussed. [ABSTRACT FROM AUTHOR]

The complete mitochondrial genome of a cryptic species of tadpole shrimp from South Africa (Accession Number: MG770893) was recovered by low coverage shotgun sequencing. The mitogenome consists of 15,216 bp with a GC content of 30.95%. COX1 sequence alignment indicates that this specimen is the most closely related to Triops granarius with a pairwise nucleotide identity of less than 90% (86.6%). Phylogenetic analysis using whole mitogenome dataset supports its affiliation to the genus Triops with moderate support for its relatively basal position within the clade.

The present species Triops cancriformis simplex was not recorded in Taif and Kingdom of Saudi Arabia before. The present work is a confirmatory study to indicate the identity of this species in the ephemeral freshwater bodies in Taif, KSA and to ascertain that, if there is any other Triops species in the same area or not. Four sites were investigated in Taif governorate; Wadi Al-Arj, Saysed, Jabajeb pool and Ghadeer Al-Banat. The animal was not recorded in the first two sites all the year. The specimens were collected from Jabajeb pool on Al-Hada road and Ghadeer Al-Banat at Al-Roddaf region. No specimens were found in these sites during winter and autumn but they start in late spring and summer. One hundred and seven specimens were collected from both sites in this period. The animal was morphologically described to be distinguished from the other large branchiopods species. The supra-anal plate is absent, the dorsal organ of the present species is rounded, second maxilla is present, no supernumerary spines on apodous rings, the carina of T. c. simplex is smooth without spines in front of its terminal spine and presence of small spines on the furca.

The tadpole shrimp (Triops longicaudatus) is an aquatic crustacean that helps control pest populations. It inhabits freshwater ponds and pools and has been described as a living fossil. T. longicaudatus was officially declared an endangered species South Korea in 2005; however, through subsequent protection and conservation management, it was removed from the endangered species list in 2012. The limited number of available genetic resources on T. longicaudatus makes it difficult to obtain valuable genetic information for marker-aided selection programs. In this study, whole-transcriptome sequencing of T. longicaudatus generated 39.74 GB of clean data and a total of 269,822 contigs using the Illumina HiSeq 2500 platform. After clustering, a total of 208,813 unigenes with an N50 length of 1089 bp were generated. A total of 95,105 unigenes were successfully annotated against Protostome (PANM), Unigene, Eukaryotic Orthologous Groups (KOG), Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) databases using BLASTX with a cut-off of 1E5. A total of 57,731 unigenes were assigned to GO terms, and 7247 unigenes were mapped to 129 KEGG pathways. Furthermore, 1595 simple sequence repeats (SSRs) were detected from the unigenes with 1387 potential SSR markers. This is the first report of high-throughput transcriptome analysis of T. longicaudatus, and it provides valuable insights for genetic research and molecular-assisted breeding of this important species. [ABSTRACT FROM AUTHOR]

Background: In a deep sequencing analysis of small RNAs prepared from a living fossil, the tadpole shrimp Triops cancriformis, a 32-nt small RNA was specifically detected in the adult stage. A nucleotide sequence comparison between the 32-nt small RNA and predicted tRNA sequences in the draft nuclear genomic DNA showed that the small RNA was derived from tRNAGly(GCC). To determine the overall features of the tRNA-derived fragments (tRFs) of T. cancriformis, the small RNA sequences in each of the six developmental stages (egg, 1st - 4th instar larvae, and adult) were compared with the mitochondrial and nuclear tRNA sequences. Results: We found that the tRFs were derived from mitochondrial and nuclear tRNAs corresponding to 16 and 39 anticodons, respectively. The total read number of nuclear tRFs was approximately 400 times larger than the number of mitochondrial tRFs. Interestingly, the main regions in each parental tRNA from which these tRFs were derived differed, depending on the parental anticodon. Mitochondrial tRFSer(GCU)s were abundantly produced from the 5' half regions of the parental tRNA, whereas mitochondrial tRFVal(UAC)s were mainly produced from the 3' end regions. Highly abundant nuclear tRFs, tRFGly(GCC)s, tRFGly(CCC)s, tRFGlu(CUC)s, and tRFLys(CUU)s were derived from the 5' half regions of the parental tRNAs. Further analysis of the tRF read counts in the individual developmental stages suggested that the expression of mitochondrial and nuclear tRFs differed during the six stages. Based on these data, we precisely summarized the positions of the tRFs in their parental tRNAs and their expression changes during development. Conclusions: Our results reveal the entire dynamics of the tRFs from both the nuclear and mitochondrial genomes of T. cancriformis and indicate that the majority of tRFs in the cell are derived from nuclear tRNAs. This study provides the first examples of developmentally expressed mitochondrial tRFs. [ABSTRACT FROM AUTHOR]

The large branchiopod crustaceans (fairy shrimp, tadpole shrimp, and clam shrimp) of India have been examined with varying degrees of scientific rigour since the late 1800s. Although 86 nominal species have been reported for India, the validity of many is in question - particularly for the clam shrimp. Most Indian endemic taxa are poorly described; some lack type material or the type material has been lost. Most recent revisions of key groups have made no attempt to validate identifications using existing type material, or even to procure topotype material. Worse, recent reviews treat old synonyms as valid names without any analysis or explanation. We provide a review of the taxa from the Indian subcontinent (Bangladesh, India, Nepal, Pakistan, and Sri Lanka) taking a strongly conservative approach to assessing the reported species. We recognize only 42 species: 16 anostracans, 2 notostracans, 3 laevicaudatans, 21 spinicaudatans (with reservations), and a single species of cyclestherid. This should establish a base point for future work on the branchiopods of the subcontinent. [ABSTRACT FROM AUTHOR]

The present species Triops cancriformis simplex was not recorded in Taif and Kingdom of Saudi Arabia before. The present work is a confirmatory study to indicate the identity of this species in the ephemeral freshwater bodies in Taif, KSA and to ascertain that, if there is any other Triops species in the same area or not. Four sites were investigated in Taif governorate; Wadi Al-Arj, Saysed, Jabajeb pool and Ghadeer Al-Banat. The animal was not recorded in the first two sites all the year. The specimens were collected from Jabajeb pool on Al-Hada road and Ghadeer Al-Banat at Al-Roddaf region. No specimens were found in these sites during winter and autumn but they start in late spring and summer. One hundred and seven specimens were collected from both sites in this period. The animal was morphologically described to be distinguished from the other large branchiopods species. The supra-anal plate is absent, the dorsal organ of the present species is rounded, second maxilla is present, no supernumerary spines on apodous rings, the carina of T. c. simplex is smooth without spines in front of its terminal spine and presence of small spines on the furca. [ABSTRACT FROM AUTHOR]

We investigated the interactions of tadpole shrimp, a mosquito biological control agent, with the juvenile hormone analog methoprene and a monomolecular surface film. In laboratory assays, the tadpole shrimp (TPS) Triops newberryi (Packard) was able to tolerate high concentrations of methoprene without negative impacts on its growth, longevity, and fecundity when exposed to 1 to 10 mg/liter, or 90-900 fold, of the IE90 levels against a laboratory colony of Culex quinquefasciatus Say. The same held true in field trials when the habitats were treated with Altosid® Liquid Larvicide (Altosid® LL, 5% methoprene) at 0.3-1.2 liters/ha. or 1-4 fold of the label rates for mosquito control. However, some significant impacts on the TPS occurred when they were exposed to Agnique® Monomolecular Film (Agnique® MMF) at the label rates for mosquito control ranging from 1.89-9.45 liters/ha. under laboratory and field conditions. To avoid the negative impact of Agnique MMF on tadpole shrimp, it appears that 1.89 liters/ha. would be the maximum rate when Agnique MMF is used to control mosquitoes in the habitats where the TPS is employed as a biological control agent, or prevailing in the aquatic habitats with potential for suppressing mosquito larval populations. [ABSTRACT FROM AUTHOR]

The tadpole shrimp (Notostraca: Triops) have been called living fossils with conserved morphology, but subtle morphological variations within and between species has yielded confused taxonomic assignments. To aid in cryptic species detection of tadpole shrimp from southern New Mexico, USA, the first complete mitochondrial genomes for three putative species (T. longicaudatus "long," T. 1. "short," T. newberryi) are reported. The genomes ranged in length from 15,058 bp to 15,060 bp with 13 coding genes, 22 tRNA genes, 2 rRNA genes and a control region. Phylogenetic trees were constructed using previously sequenced Triops-genomes to assess genetic relationships within the genus. The T. longicaudatus-genomes from Genbank were consistent with our genomes for T. newberryi and T. l. "short." Variation in mitochondrial genes were identified that will aid future identification of cryptic lineages of tadpole shrimp. Genetic differentiation among the genomes of Triops in New Mexico support elevation to species status. [ABSTRACT FROM AUTHOR]

The tadpole shrimp, Triops sinensis, was discovered in the paddy fields of the Shouchang River watershed. The gut contents of the shrimp from these field populations were analyzed in order to quantify their dietary patterns. Some species of tadpole shrimps were found to prey on mosquito larvae as well as uproot weeds. Mosquito larvae and weeds were seldom found in the paddy fields which the tadpole shrimp inhabited in the Shouchang River watershed. The results further showed that the larvae of these tadpole shrimp mainly feed on algae and rice lamina. The tadpole shrimp could feed on animal food including protozoa, nematodes, rotifers, crustaceans, and aquatic insect larvae, though the animal food was subsidiary. [ABSTRACT FROM AUTHOR]

The gonadic histology of the tadpole shrimp Triops sp. from 22 Mexican locations was determined using light microscopy to investigate the hermaphroditic tissue. The sex ratio and type of morphotypes were also determined. Short morphotype individuals with ovisacs (58) were hermaphrodites and were recorded from 14 locations. Of the 34 long morphotype individuals with ovisacs, 25 were hermaphrodites recorded from seven locations, whereas nine were females recorded from only three locations. The proportion of males in hermaphrodite populations ranged from zero to 21%. Thus we infer that such populations have an androdioic reproduction. In female populations, it ranged from 50 to 62%; therefore such populations have a gonochoric reproduction. [ABSTRACT FROM AUTHOR]

The living fossil Triops cancriformis comprises bisexual (either gonochoric or hermaphroditic) and unisexual populations. Genetic surveys have recently revealed a general trend of low differentiation of 12S and 16S mitochondrial genes. We, therefore, surveyed further mitochondrial (COI gene and control region) and nuclear markers (dinucleotide microsatellites) to assess the genetic variability and to establish any relationship with the different reproductive modes found in European populations. The mitochondrial analyses confirmed the pattern of low variability. Hence, the low mitochondrial genetic variability appears as a common feature of the genus Triops. The microsatellite analysis found that Italian populations are monomorphic or exhibit little polymorphism, while other European samples display a higher degree of polymorphism and private alleles. Spanish, Austrian and Italian populations show patterns of Hardy–Weinberg disequilibrium that could be explained by the mode of reproduction, or by a higher frequency of null alleles in these populations. The low diversity and differentiation among Italian populations lead us to question the Monopolization Hypothesis. One microsatellite locus appears to be sex-linked, with heterozygotes detected only in males and hermaphrodites.Heredity (2008) 100, 496–505; doi:10.1038/hdy.2008.3; published online 20 February 2008 [ABSTRACT FROM AUTHOR]

For the crustacean class Branchiopoda, we estimated global species richness, assessed the reliability of relative diversity estimates among higher taxa and made predictions about the kinds of species remaining to be described. Global. We calculated correction factors to account for three different sources of diversity underestimation, analysed taxonomic patterns of species descriptions over time and tested possible correlates of description date. Our work suggests that there are c. 2.1 times more branchiopod species in nature than the c. 1180 currently described. The largest correction factor was at the scale of single biogeographical regions, mainly attributed to poor knowledge of species diversity within described morphospecies. Relative diversity estimates among major taxonomic groups are apparently quite reliable, with diversity differences greater than 1.5-fold robust to the heterogeneity of the taxonomic process. Current knowledge of branchiopod diversity is biased towards species with large geographical ranges, whereas body size and higher taxonomic group were only weak predictors of description date. A proper understanding of species boundaries in nature, which is greatly aided by molecular studies, is key in accurately estimating species richness for invertebrate groups. However, we suggest that while many species remain to be described, numbers of presently described species are still useful for macroevolutionary studies of diversification when interpreted with caution. [ABSTRACT FROM AUTHOR]

The tadpole shrimp (TPS), Triops newberryi (Packard) (Notostraca: Triopsidae), is a potential biological control agent for immature mosquitoes breeding in ephemeral habitats. Studies were initiated in the laboratory to investigate the effects of some ecological and physiological factors on egg hatch. When subjected to successive hydrations, most of the hatch occurred in the first hydration with additional hatches noted in the second and third hydrations. In each hydration, most of the eggs hatched in 12 to 48 h. Temperature had a marked effect on egg hatch. Preconditioning treatment of eggs in soil at extreme temperatures lowered egg hatch in succeeding hydrations. Temperature during hydration also influenced egg hatch, with maximum hatch at 29°C. Length of photoperiod was another ecological factor affecting egg hatch; darkness during the hydration period reduced egg hatch. As a simulation of incomplete hydration commonly encountered in arid regions associated with light precipitation and scarce irrigation water, TPS eggs in soil were wetted and flooded for short time periods. These treatments enhanced egg hatch during succeeding full hydrations. The presence of soil during preconditioning and hatching did not affect egg hatch. High water salinity reduced or prevented egg hatch. Preconditioning treatment at high water salinity lowered egg hatch during succeeding hydrations with distilled water. Maximum egg hatch occurred at pH 7; preconditioning treatment at pH 3 lowered and at pH 11 eliminated egg hatch during succeeding hydrations with distilled water. TPS eggs from dead gravids (unlaid eggs) did not hatch after proper preconditioning and hydration. [Copyright &y& Elsevier]

The complete mitochondrial genome of a cryptic species of tadpole shrimp from South Africa (Accession Number: MG770893) was recovered by low coverage shotgun sequencing. The mitogenome consists of 15,216 bp with a GC content of 30.95%. COX1 sequence alignment indicates that this specimen is the most closely related to Triops granarius with a pairwise nucleotide identity of less than 90% (86.6%). Phylogenetic analysis using whole mitogenome dataset supports its affiliation to the genus Triops with moderate support for its relatively basal position within the clade. [ABSTRACT FROM AUTHOR]

The tadpole shrimp [Triops longicaudatus (Leconte)] has emerged as a significant pest of rice grown in California in recent decades. The change in T. longicaudatus' pest status has coincided with changes in cultural management of residual rice straw postharvest. Policy changes have reduced the postharvest burning of fields from nearly 95% to less than 10%, promoting increased use of winter flooding as a means of accelerating straw decomposition. Field and laboratory trials were conducted from 2015 to 2017 at the Rice Experiment Station in Biggs, CA and in greenhouses at the University of California (UC) Davis to evaluate the effects of burning, flooding, and a fallow control on T. longicaudatus population dynamics. Experiments demonstrated that burning of rice straw failed to suppress densities of hatching T. longicaudatus and actually had the reverse effect, causing a 51% increase in numbers hatching, perhaps as a result of burning triggering termination of multiyear T. longicaudatus egg dormancy. Winter flooding had no measurable effect on T. longicaudatus hatch. Thus, these changes in winter cultural practices do not appear to be responsible for the emergence of T. longicaudatus as a major rice pest., (© The Author(s) 2020. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

The mitochondrial genome sequence of the Australian tadpole shrimp,Triops australiensisis presented (GenBank Accession Number: NC_024439) and compared with otherTriopsspecies.Triops australiensishas a mitochondrial genome of 15,125 base pairs consisting of 13 protein-coding genes, 2 ribosomal subunit genes, 22 transfer RNAs, and a non-coding AT-rich region. TheT. australiensismitogenome is composed of 36.4% A, 16.1% C, 12.3% G and 35.1% T. The mitogenome gene order conforms to the primitive arrangement for Branchiopod crustaceans, which is also conserved within the Pancrustacean. [ABSTRACT FROM PUBLISHER]

The tadpole shrimp ( Triops longicaudatus) is an aquatic crustacean that helps control pest populations. It inhabits freshwater ponds and pools and has been described as a living fossil. T. longicaudatus was officially declared an endangered species South Korea in 2005; however, through subsequent protection and conservation management, it was removed from the endangered species list in 2012. The limited number of available genetic resources on T. longicaudatus makes it difficult to obtain valuable genetic information for marker-aided selection programs. In this study, whole-transcriptome sequencing of T. longicaudatus generated 39.74 GB of clean data and a total of 269,822 contigs using the Illumina HiSeq 2500 platform. After clustering, a total of 208,813 unigenes with an N 50 length of 1089 bp were generated. A total of 95,105 unigenes were successfully annotated against Protostome (PANM), Unigene, Eukaryotic Orthologous Groups (KOG), Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) databases using BLASTX with a cut-off of 1E-5. A total of 57,731 unigenes were assigned to GO terms, and 7247 unigenes were mapped to 129 KEGG pathways. Furthermore, 1595 simple sequence repeats (SSRs) were detected from the unigenes with 1387 potential SSR markers. This is the first report of high-throughput transcriptome analysis of T. longicaudatus , and it provides valuable insights for genetic research and molecular-assisted breeding of this important species., Competing Interests: The authors declare no conflict of interest.

We investigated the interactions of tadpole shrimp, a mosquito biological control agent, with the juvenile hormone analog methoprene and a monomolecular surface film. In laboratory assays, the tadpole shrimp (TPS) Triops newberryi (Packard) was able to tolerate high concentrations of methoprene without negative impacts on its growth, longevity, and fecundity when exposed to 1 to 10 mg/liter, or 90-900 fold, of the IE(90) levels against a laboratory colony of Culex quinquefasciatus Say. The same held true in field trials when the habitats were treated with Altosid(®) Liquid Larvicide (Altosid(®) LL, 5% methoprene) at 0.3-1.2 liters/ha. or 1-4 fold of the label rates for mosquito control. However, some significant impacts on the TPS occurred when they were exposed to Agnique(®) Monomolecular Film (Agnique(®) MMF) at the label rates for mosquito control ranging from 1.89-9.45 liters/ha. under laboratory and field conditions. To avoid the negative impact of Agnique MMF on tadpole shrimp, it appears that 1.89 liters/ha. would be the maximum rate when Agnique MMF is used to control mosquitoes in the habitats where the TPS is employed as a biological control agent, or prevailing in the aquatic habitats with potential for suppressing mosquito larval populations., (© 2014 The Society for Vector Ecology.)

Electrophoretic analysis of 31 populations, ranging from California to Kansas, indicates that the tadpole shrimp Triops longicaudatus (LeConte) is actually a mixture of at least two reproductively isolated species. In the central United States, the predominant species is T. longicaudatus. Which is found typically in ephemeral prairie pools. In the southwestern United States, the predominant species is Triops newberryi (Packard), which characteristically inhabits large playa pools. The two species coexist occasionally and in sympatric situations they are reproductively isolated from each other. The two species aregenetically distinct at a level greater than is typical of conspecific populations. These genetic differences are correlated with subtle morphological differences and profound differences in reproductive biology. Both species represent complexes of bisexual and unisexual populations. Bisexual populations of T. longicaudatus are usually composed of males and females in approximately equal frequencies; bisexual populations of T. newberryi are composed of males in low frequencies and self compatible hermaphrodites. Unisexual populations of both specie apparently consist entirely of self-compatible hermaphrodites. [ABSTRACT FROM AUTHOR]