Heart Rate during Breathing and Apnea in Marine Snakes (Reptilia, Serpentes)
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Breathing was associated with an elevated heart rate and apnea with lower rates, the pattern and level of change varying with activity and breathing frequency. Inactive snakes breathing infrequently achieved a low, stable heart called the apneic heart rate, which is distinct from diving bradycardia. Breathing tachycardia occurred in anticipation of the actual initiation of ventilation. Activity caused an elevation in heart rate during apnea. Resting heart rates were similar to those of other diving reptiles but somewhat lower than those of non-diving species, although comparisons were tentative because of the different methodologies used by different investigators. In the evening, breathing tachycardia was reduced; consequently heart rate differences between breathing and apnea were smaller than during the day. The physiological adaptations of marine snakes to their environment seem to consist of quantitative rather than qualitative departures from the basic reptilian mode. * * *Keywords:
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The eggs, larvae, and pupae (male and female) of three Japanese species of the Bibionidae, Plecia adiastola, P. membranifera, and P. hadrosoma, are described and illustrated, and ecological notes are included. Morphological characters of the immature stages of Plecia species are compared for the first time, and a diagnosis is presented. The taxonomic and phylogenetic importance of morphological characters, especially of the larval head and the arrangement of the larval and pupal body processes, is discussed.
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The parasite Crithidia mellificae (Kinetoplastea: Trypanosomatidae) infects honeybees, Apis mellifera. No pathogenic effects have been found in individual hosts, despite positive correlations between infections and colony mortalities. The solitary bee Osmia cornuta might constitute a host, but controlled infections are lacking to date. Here, we challenged male and female O. cornuta and honeybee workers in laboratory cages with C. mellificae. No parasite cells were found in any control. Parasite numbers increased 6.6 fold in honeybees between days 6 and 19 p.i. and significantly reduced survival. In O. cornuta, C. mellificae numbers increased 2–3.6 fold within cages and significantly reduced survival of males, but not females. The proportion of infected hosts increased in O. cornuta cages with faeces, but not in honeybee cages without faeces, suggesting faecal – oral transmission. The data show that O. cornuta is a host of C. mellificae and suggest that males are more susceptible. The higher mortality of infected honeybees proposes a mechanism for correlations between C. mellificae infections and colony mortalities.
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The two Cryptophis species are moderate-sized (up to 1 m length) nocturnal ven- omous snakes of northern and eastern Australia. Examination of 600 museum specimens provided data on body sizes, sexual size dimorphism, reproductive cycles and food habits. Males attain larger body sizes than females in C. nigrescens, but not in C. pallidiceps. Both species are viviparous, with a mean litter size of four. Parturition occurs in late summer (Feb.-Mar.) in southern populations, but may be earlier in snakes from tropical areas. Relative clutch mass averaged 60% in captive C. nigrescens, and offspring averaged 152 mm SVL and 2.3 g mass at birth. Male combat was recorded in C. nigrescens. Both Cryptophis species feed on reptiles, especially scincid lizards (89% of all prey items found). A wide range of skinks is taken, but most are diurnally-active forms. Like many other Australian elapids, Cryptophis forage nocturnally for sleeping skinks. The absence of frogs from the diets of such elapids is a consistent but puzzling phemonenon. Relative eye size in Cryptophis is similar to that in other nocturnal elapids. The proteroglyphous snakes of Aus- tralia are best-known for their highly toxic venoms; several of the large elap- ids are more deadly to man than are any snakes from other continents (Broad et al., 1979). However, these large and spectacular species constitute only a mi- nor part of the radiation of the Elapidae in Australia. Most elapids are small and secretive; although they may be abun- dant, they have attracted little popular or scientific attention. The present study
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Seasonal variation in the male and female reproductive cycle of the viviparous scincid Mabuya capensis is described. Females exhibited a winter to summer vitellogenic period with ovulation occurring during mid-spring to mid-summer. The onset of vitellogenesis coincided with increasing en- vironmental temperatures and photoperiod. Gravid females were collected from October to February, with parturition occurring during December through February. Females produced 8-20 embryos and clutch size was positively correlated with female body size. Males exhibited a basic prenuptial spermatogenic cycle with spermatogenesis commencing during late summer to autumn. Males became reproductively active during a period of decreasing ambient temperature, photoperiod, and rainfall. Peak spermiogenesis oc- curred during late winter to early summer at which time testis volumes were maximal. Testicular regression followed during summer, with testis volumes at minimum values.
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The Liophis cobella group consists of four species, L. breviceps, L. cobella, L. frenatus, and L. longiventris. The color pattern of the species in this group consists of a dark brown to black ground color with narrow light bands. The banding may be obscure in old adults, but the venter is consistently banded or checkered with black and coral red marks. The average number of dorsal bands, ventrals, subcaudals, maxillary teeth and tail length as a percentage of total length among the species of the group varies from 30-90, 138-189, 50-59, 15-22, and 17.0-20.0 respectively. Num- bers of scale rows are invariably 17-17-15, scales smooth, without apical pits. A brief history of the names of some species and keys to the species and subspecies are presented for the group. The group previously was thought to consist of eight species among 14 named forms, but addi- tional material from other localities have shown overlap of features between some taxa previously regarded as full species, resulting in the reduction to subspecific status of L. canaimus and L. trebbaui; the recognition of L. taeniogaster as a valid subspecies; the description of a new subspecies; and the placement of the currently recognized species L. brazili and L. ingeri as junior subjective synonyms of L. frenatus and L. cobella, respectively. One form, Coluber cinereus Linnaeus, cannot be allocated to any currently recognized colubrid genus.
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The eggs of Limnophora exsurda are described. The larva is in the 3rd stage when it emerges from the egg. The absence of larval trimorphism has been described in a number of dipterous larvae and appears to be correlated with a carnivorous mode of life in the larval stage. Notes on the nomenclature of L. exsurda by Mr J. E. Collin are given.
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Geoplana josefi sp. nov. of South Brazil is described herein. The species shows etary polymorphism. Neither youngs nor adults show the characteristic colour pattern of the mature worms. The species has a multilayered lining in the female atrium. The allopatric G. trigueira, which does not have such a lining, is similar externally and internally with adults of G. josefi, its seminal vesicle, however, being unpaired.
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