A new allocreadiid (Trematoda) species from freshwater fish Heterandria bimaculata (Teleostei: Poeciliidae) in Southeastern Mexico

Paracreptotrema heterandriae n. sp. (Trematoda: Allocreadiidae) is described from the intestine of the freshwater fish Heterandria bimaculata (Teleostei: Poeciliidae) from the upper basin of Río La Antigua, in Veracruz, Mexico. The new species is distinguished from the 3 others in the Paracreptotrema Choudhury, Pérez-Ponce de León, Brooks, and Daverdin, 2006 , mainly by having a feeble membranous cirrus sac containing an uncoiled seminal vesicle, instead of a well-developed muscular cirrus sac that encloses coiled seminal vesicle, pars prostatica, and ejaculatory duct as in the previously 3 nominal species. Moreover, eggs of the new species are larger than all others ([measurements in micrometers] eggs of P. heterandriae n. sp. 72.5 [70-75] × 40 [35-41]; P. blancoi 55.4 [52.5-62.5] × 38.5 [32.5-42.5]; P. mendezi 46 × 37; P. profundulusi 57 [52-60] × 27.8 [25-30]).     

Untersuchungen zur Dotterbildung in den Oocyten von Xiphophorus helleri (Heckel, 1848) (Teleostei,Poeciliidae)

Zusammenfassung Die Verteilung von Nucleinsäuren, Polysacchariden, Proteinen und Fetten in den verschiedenen Entwicklungsstadien der Oocyten von Xiphophorus helleri wurde histochemisch untersucht. Junge Oocyten enthalten viel RNS und Proteine, aber wenig Fett. Während der Vitellogenese steigt der Gehalt an Fetten, Glycoproteide werden eingebaut. Die dazu nötigen Stoffe werden aus dem mütterlichen Körper in niedermolekularer, löslicher Form über das Follikelepithel zur Oocyte transportiert. Diese histochemischen Befunde werden durch Ergebnisse der Elektrophorese gestützt. In elektronenmikroskopischen Untersuchungen wurden den histochemischen Fakten weitere morphologische Grundlagen zugeordnet. Während der Prävitellogenese tritt ein Dotterkern auf, der sich vor Beginn der Dotterbildung auflöst. Coated vesicles nehmen Material aus dem perioocytären Interzellularraum auf. Zellstrukturen der Oocyte beteiligen sich am Dotteraufbau. Besonders auffallend sind die Veränderungen an den Mitochondrien. In der Zusammensetzung des Dotters und in der Beteiligung der Organellen gibt es Unterschiede zu Lebistes. Injektionen von Myofer runden die Ergebnisse ab. Vom maternalen zum embryonalen Gewebe erfolgt ein Transport von Nährstoffen, nicht nur Gasaustausch. Die Definition der Ovoviviparie muß daher erweitert werden.

---

Studies on yolk formation in oocytes of Xiphophorus helleri

Summary The distribution of nucleic acids, polysaccharides, proteins, and fats in different developmental stages of oocytes of Xiphophorus helleri was studied using histochemical methods. Young oocytes had high RNA and protein contents. During vitellogenesis, the fat content increased and glycoproteins were deposited. These substances were transported from the maternal body into the oocyte in a soluble, small molecular form. The histochemical results were supported by our studies using electrophoretic and electron microscopic methods. During previtellogenesis, a yolk nucleus appeared. Coated vesicles took up material from the intercellular space around the oocyte. Differences between Xiphophorus and Lebistes were observed in the composition of yolk and in the prevalent types of ultrastructural organelles present. In Xiphophorus, labelling by Myofer (intraperitoneal or intramuscular injections) verified the transport of nutritive material from the maternal body into oocytes (Stage III and IV) and embryonic tissues. This suggests that in Xiphophorus the definition of ovoviviparity has to be modified.

     

Functional morphology of the gonoduct of the viviparous teleost Poeciliopsis gracilis (Heckel, 1848) (Poeciliidae)

Female teleosts do not develop Müllerian ducts; consequently, the ovary of teleosts contains two zones: germinal and gonoduct. The gonoduct lacks germinal cells, but has relevant functions in the reproductive process. We describe the functional morphology of the gonoduct in the viviparous teleost Poeciliopsis gracilis during nongestation and gestation stages. This study tests the hypothesis that the gonoduct functions as a barrier between the germinal zone and the exterior. By providing information about morphology and function of the gonoduct we show that this part of the ovary has an essential role in the reproduction of teleosts. The ovaries were processed by histological technique and stained with hematoxylin‐eosin (H‐E), Masson's trichrome, toluidine blue and periodic acid‐Schiff (PAS). The gonoduct is divided into three regions: cephalic, middle, and caudal. In the cephalic and middle regions there are mucosal folds that extend into the gonoductal lumen, forming structures similar to a cervix. The caudal region has two portions: the anterior contains a dorsal invagination and exocrine glands among columnar cells; the posterior has a ventral flexion and stratified epithelium with apical secretory cells. The morphology of this epithelium indicates two functions: (a) secretory by the apical columnar cells, and (b) protection through the stratification. Another peculiarity of the caudal region is that both ducts, reproductive and digestive, converge in a common cavity at their caudal ends, forming a cloacal region. The histology of the gonoduct indicates relevant functions including: (1) the control of the luminal diameter by the muscle and the presence of mucosal folds, like a cervix; (2) the relationship with the spermatozoa during insemination and storing them in mucosal folds; (3) the support of immunological processes; (4) secretory activities; (5) forming the duct during birth; and (6) possibly, acts as a barrier against parasite infestations.     

The first record of the swordtail Xiphophorus hellerii Heckel, 1848 (Poeciliidae,Actinopterygii) established in the wild from Morocco

Aquarium and ornamental fish trade is currently recognized as a major source of invasive species in aquatic ecosystems around the world. The swordtail Xyphophorus hellerii is a popular ornamental freshwater fish that occurs as an introduced species in the aquatic habitats of at least thirty-one countries. We report the first finding of an established population of the swordtail in Morocco. Twelve individuals of X. hellerii were captured along Oued Ain Chkef inside the park (Fez Province), including females and males (mature and immature). Ongoing investigations could soon reveal more occurrences of this species in the country.     

Superfetation in the viviparous fish Heterandria formosa (Poeciliidae)

Heterandria formosa is a viviparous poeciliid native of the southeastern of United States of America. H. formosa exhibits unique reproductive features as: (a) production of extremely small eggs with scarce quantity of yolk (microlecithal eggs), (b) consequently, a high level of matrotrophy and development of a complex follicular placenta, (c) ovarian sperm storage that allows the continuous fertilization of oocytes and production of offspring and (d) development of high degree of superfetation. The degree of superfetation refers to the number of broods in different simultaneous stages of gestation. Morphological evidence of the degree of superfetation in H. formosa has not been documented. Therefore, and because of the general interest in the complex process of superfetation, the goal of this study is to morphologically define the degree of superfetation of H. formosa through two procedures: (a) histological analysis of entire ovaries in gestation and (b) dissection of visible embryos and the histological analysis of the remaining ovarian tissue. Results indicate that H. formosa can gestate up to seven broods at the same time.     

Spinitectus mexicanus n. sp. (Nematoda : Cystidicolidae) from the intestine of the freshwater fish Heterandria bimaculata in Mexico

A new nematode, Spinitectus mexicanus n. sp., is described on the basis of the specimens recovered from the intestine of Heterandria bimaculata (Heckel) (Poeciliidae, Cyprinodontiformes) from 3 rivers of the Papaloapan River basin (type locality La Basura River), Los Tuxtlas, Veracruz State, Mexico. It differs from its congeners mainly in having the spination of the cuticle separated into 4 longitudinal sectors, each with posteriorly diminishing numbers of larger spines at the anterior part of body. It is the first species of Spinitectus described from a poeciliid fish and the second reported from freshwater fishes in Mexico.     

Insemination,intrafollicular fertilization and development of the fertilization plug during gestation in Heterandria formosa (Poeciliidae)

The viviparous teleost Heterandria formosa is a remarkable species for its reproductive characters including: (a) the smallest oocyte in viviparous fish species; (b) a high level of matrotrophy with a complex placenta; and (c) the highest level of superfetation. Superfetation involves (d) the continuous development of oocytes and fertilization at the same time with embryos in gestation. The sequential fertilization of oocytes requires (e) storage of spermatozoa in the ovary. Among these characteristics, fertilization is of fundamental interest, specifically the intrafollicular fertilization of poeciliids, species that do not present micropyle, and the consequent formation of the fertilization plug, a structure developed at the periphery of the follicle where the entrance of spermatozoa occurs. Both processes intrafollicular fertilization and formation of the fertilization plug have been rarely described. There is only one study illustrating, the fertilization plug of H. formosa with a drawing. In the context of reproductive aspects of H. formosa, the goal of this study is to describe the morphology of the ovary during insemination, intrafollicular fertilization and development of the fertilization plug. After insemination, spermatozoa enter the ovary and occupy folds of the lamella near follicles of all stages of oogenesis, the delle, where the germinal epithelium establishes contact with the follicular epithelium. The results of the present study provide evidence that both epithelia open at the distal end of the delle, this morphological change allow that the spermatozoa to make contact with the zona pellucida of the oocyte. After fertilization, the delle becomes blocked by proliferation of cells of the germinal epithelium, to form the fertilization plug that persists throughout gestation. Abundant reticular fibers and blood vessels are seen around the fertilization plug. Persistence of the fertilization plug suggests that it could be the site where the juvenile will gain entrance to the ovarian lumen during birth.     

Reproductive biology of Gambusia affinis holbrooki Baird and Girard, Xiphophorus helleri (Gunther) and X. maculatus (Heckel) (Pisces; Poeciliidae) in Queensland, Australia

The reproductive biology of three introduced Poeciliidae, Gambusia affinis holbrooki Baird and Girard, Xiphophorus helleri (Günther) and X. maculatus (Heckel) was studied over a 14-month period in Brisbane, Queensland. Photoperiod and water temperature determined the length of the breeding season in G. affinis , which produced up to nine broods between August and March, with the peak of reproductive activity in October. Fecundity was linearly related to body weight in G. affinis (mean fecundity = 22.78 ± 1.02, range = 3–108 offspring per brood).
Xiphophorus helleri bred from August to May, producing eight to nine broods, with peak reproductive activity from October to December. Fecundity was curvilinearly related to body weight (mean fecundity = 60.15 ± 3.8, range = 7–183 offspring per brood. Xiphophorus maculatus bred between September and March, producing five to six broods during the study period. Fecundity was linearly related to standard length (s.l.) (mean fecundity = 27.27 ± 2.4, range = 3–92 offspring per brood). Although the reproductive strategy of the three species differs, all have the capacity to build up large populations in south-eastern Queensland. Their present distributions and relative abundance are discussed.     

A new nematode species (Seuratoidea, Cucullanidae) parasitizing Parauchenipterus striatulus (Steindachner, 1876) (Pisces, Auchenipteridae) in Brazil

A new species of a cucullanid nematode is described, illustrated and compared with Cucullanus brevispiculus Moravec, Kohn & Fernandes, 1993 and C. rhamphichthydis Moravec, Kohn & Fernandes, 1997, two species previously reported as parasitizing freshwater fish in South America. The new species is characterized mainly by markedly short spicules, deirids and excretory pore situated posterior to the oesophago-intestinal junction, presence of strongly sclerotized plates in the oesophastome and oesophagus divided into two distinct portions.     

A new family of Strepsiptera parasitizing fruit flies (Tephritidae) in Australia

ABSTRACT. A new family of Strepsiptera (Dipterophagidae) from Australia containing a new genus and species ( Dipterophagus daci ) is described and figured. This is the first species of Strepsiptera to be described as a parasite of Diptera. D.daci is recorded from ten fruit fly species, viz Dacus aquilonis (May), D.bellulus Drew, D.cacuminatus (Hering), D.decurtans (May), D.mayi Hardy, D.neohumeralis Hardy, D.peninsularis Drew, D.tenuifascia (May), D.tryoni (Froggatt) and Dacus sp. n. ( near musae ). Gregarious parasitism (two to six adult parasites per fly) is common.     

Gonopodial system review and a new fish record of Poeciliopsis infans (Cyprinodontiformes: Poeciliidae) for Lake Patzcuaro,Michoacan, central Mexico

Since 1997, Poeciliopsis infans Woolman 1894 has been recognized as a new inhabitant of Lake Patzcuaro, Michoacan in Central Mexico. Between February 1997 and October 1998, nine fish samples were collected at Lake Patzcuaro. Morphometric and meristic counts were conducted on a random selection of 40 organisms of both sexes of Poeciliopsis infans. Males of these viviparous fish posses a modified anal fin called gonopodium. The characteristic hemal spine on the 18th caudal vertebra for this species is described herein and the bony components of the gonopodial structure and suspensoria that together comprise the gonopodial system, which is important for taxonomic studies at various levels of classification were reviewed. Poeciliopsis infans displays a high degree of sexual dimorphism in body shape and anal fin anatomy with the most conspicuous difference observed in anal fin height, which averages 40% of SI in males and 17% in females. Comparisons between male and female anal fins are described herein as well as the possible impacts of this species on Lake Patzcuaro fish fauna.     

A new capillariid, Paracapillaria (Ophidiocapillaria) najae n. sp. (Nematoda: Trichuroidea), from an elapid snake in West Bengal, India

Paracapillaria (Ophidiocapillaria) najae n. sp. is described from specimens from the oesophagus of a single snake, Naja naja (fam. Elapidae), caught from a garden at Kalyani, West Bengal, India. It is characterised by possessing: a medium body size; sinuous muscular oesophagus; stichosome consisting of distinctly subannulated stichocytes (30–48 in number); male tail having a membranous bursa supported by two wide lateral rays with bluntly pointed distal ends and not reaching to the posterior margin of the bursa; long spicule with spatula-like extension of the proximal extremity; spicular surface transversely marked; non-spinous but transversely folded spicular sheath; vulval lips non-elevated or only anterior lip slightly elevated; and oval eggs with protruding polar plugs. This represents the first record of a capillariid worm from a snake of the family Elapidae.     

A new species of Ornithocephalus (Orchidaceae) from Oaxaca,Mexico

Ornithocephalus torresii Salazar & Soto Arenas, a new species from the Pacific slope of Oaxaca. Mexico, is described and illustrated. It is distinguished by the nearly closed, globose flowers and the cymbiform lip with a small, irregularly dentate-lacerate lobule at each side of the base. A key to all the species ofOrnithocephalus hiterto recorded from Mexico is provided.     

A new species of Malaxis (Orchidaceae) from Morelos, Mexico

A new species from the Mexican state of Morelos, Malaxis lyonnetii, is described and illustrated. It is similar to M. lepanthiflora but is distinguished by its much smaller flowers, distally uncinate basal lip lobes, and entire, rounded apical lip lobe.

---

Resumen  Se describe e ilustra a Malaxis lyonnetii, una nueva especie del estado mexicano de Morelos. Esta especie es similar a M. lepanthiflora, de la que se distingue por las flores mucho menores, los lóbulos basales del labelo distalmente uncinados y el lóbulo apical del labelo entero y redondeado.

     

A new Vaccinium (Ericaceae: Vaccinieae) from Guerrero,Mexico

Vaccinium wilburii, a striking epiphyte with pink flowers and woody tuberous roots, is described, illustrated, and compared with similar species.     

A new species of ceratozamia (Zamiaceae) from Chiapas,Mexico

Ceratozamia norstogii sp. nov. from Chiapas, Mexico is described. This species is distinct from all others in the genus in that it has a straight rachis with very narrow leaflets (3–10 mm wide) which are strongly curved and almost round in cross section when dried. It is known only from Chiapas, Mexico and in cultivation.