Systematics and taxonomy of polyclad flatworms with a special emphasis on the morphology of the nervous system

In a first survey of the Colombian polyclad fauna, a total of 25 species were collected from the rocky littoral of the Tayrona National Park, Santa Marta, Colombia and deposited at the Museo de Historia Natural Marina del INVEMAR. Six species represented first records for Caribbean region. Furthermore, a new combination Phrikoceros mopsus nov. comb, was proposed, and a possible new species of Pleioplana Faubel, 1983 was found. In addition, a new polyclad family Anocellidae was erected and four deep-sea species were described; two species from the North Pacific Ocean, Anocellidus profundus gen. nov. sp. nov. and Oligocladus voightae sp. nov., and two from the continental slope of the Gulf of Mexico, Oligocladus bathymodiensis sp. nov. and Didangia carneyi sp. nov. All except D. carneyi, were found in association with bivalves. The type material was deposited at the Field Museum of Natural History, Chicago, Illinois, USA. All taxonomic work was based on major external features and serial sagittal sections of the reproductive system. Finally, the central nervous systems (CNS) of 12 species of polyclad flatworms belonging to 11 families were examined using traditional light microscopic techniques. Even though some morphological features of the CNS probably were related to the body shape and behavior of the species, three categories could be established. These categories were based on the presence and development of globuli cell masses, the cross-sectional shape of the main nerve cords, and the tissue type surrounding the nerve cords. Well-developed globuli cell masses characterize all acotylean species examined. Furthermore, the cotylean Pericelis cata also had well-developed globuli cell masses, providing additional evidence of the close phylogenetic relationship of Pericelidae with the Acotylea. Cotylean polyclads on the other hand, exhibit only weakly developed globuli cell masses. Unique features of the CNS were found in Boninia divae which represent autapomorphies for the family and which can be linked to the behavior and body shape of this taxon. The presence of external globuli cells masses in some polyclads, forming structures similar to arthopod mushroom bodies, may be an indication of an early evolutionary adaptation

Policládidos (Platyhelminthes: "Turbellaria") del Atlántico Tropical Occidental

El phylum Platyhelminthes es considerado una ramificación ancestral dentro de los phyla bilaterales (Hyman 1951). A éste pertenecen gusanos acelomados y dorsoventralmente aplanados que carecen de sistemas circulatorio y respiratorio (Hyman 1951). Aunque Ehlers (1986) define las siguientes apomorfías para el taxón: a) ausencia de mitosis en células somáticas, por ejemplo: las células somáticas se diferencian a partir de blastómeros o células totipotenciales en estado post-embriónico; y b) células multiciliadas, donde los cilios carecen de centriolo accesorio, la monofilia del grupo no ha podido ser establecida con seguridad hasta el momento. Tradicionalmente, los platelmintos han sido divididos en gusanos de vida libre Turbellaria y los grupos parásitos Trematoda, Monogenea y Cestoda. Pero hasta la fecha ninguna apomorfia ha sido encontrada para definir los Turbellaria; se ha demostrado que caracteres como vida libre y cuerpo cubierto por epidermis multiciliada no representan características para el taxón. El término Turbellaria actualmente es usado en una manera descriptiva. Dentro de los turbelarios dos grupos pueden ser reconocidos: microturbelarios y macroturbelarios, sin embargo estas designaciones no tienen valor sistemático y sólo son usados para describir la talla

Pseudobiceros pardalis Verrill 1900, n. comb.

Pseudobiceros pardalis (Verrill, 1900) n. comb. (Figs. 1, 2)Published as part of Bolaños, Marcela, Quiroga, Sigmer Y. & Litvaitis, Marian K., 2007, Five new species of cotylean flatworms (Platyhelminthes: Polycladida) from the wider Caribbean, pp. 1-23 in Zootaxa 1650 on page 3, DOI: 10.5281/zenodo.27397

Anocellidae

Family: Anocellidae n. fam. Definition: Ilyplanoidea without eyes. Ruffled pharynx located anteriorly; long, pointed tentacles present. Gonopores separate and male copulatory apparatus positioned posterior to male pore, hence directed forwards; armed with a long and pointed stylet directed backwards. Prostatic­like glands (prostatoid organs, sensu Faubel 1983) absent. Spermiducal bulbs present instead of a true seminal vesicle. Female apparatus with Lang’s vesicle. A ventral disk of potentially sensory function, positioned anterior to the cerebral ganglion; this organ is not homologous with the cotylean sucker. Taxonomic remarks regarding the new family: According to Faubel (1983), the absence of a true prostatic vesicle is the taxonomic character defining the superfamily Ilyplanoidea which includes the families Enantiidae Graff 1889, Discocelidae Laidlaw 1903, Discoprosthididae, Euplanidae, Ilyplanidae, Mucroplanidae and Paluidae (the last five all by Faubel 1983). The ruffled pharynx and a male tract without a trace of prostaticlike glands or a prostatic vesicle would place this new species into the genus Aprostatum, within the Euplanidae. This family is defined by a ruffled, centrally located pharynx, a posteriorly­dircted male copulatory apparatus, separate gonopores, and a complete lack of prostatic­like glands (Faubel 1983). Although these characters conform to those found in our new species, an additional character found in our specimens warrants the establishment of the new family Anocellidae. The defining character of the Anocellidae is that the male copulatory apparatus is located posterior to the male gonopore and is directed anteriorly. This is exactly opposite of the condition found in the Euplanidae, where the male copulatory complex is located anterior to the male gonopore and directed posteriorly (Table 1). Using a single character as a basis for a new family without a complete reanalysis of acotylean classification may appear precipitous, however, “orientation of male copulatory apparatus” weighs heavily in the classification system of acotyleans and has previously been used in defining families (Faubel 1983). In fact, Lang (1884) used it as the main character to establish the Cestoplanidae, a group in which the male copulatory apparatus is located posterior to the male gonopore and is directed anteriorly. Other morphological differences however eliminate placement of the new species in the Cestoplanidae (Table 1), thus justifying the establishment of the family Anocellidae.Published as part of Quiroga, Sigmer Y., Bolaños, D. Marcela & Litvaitis, Marian K., 2006, First description of deep­sea polyclad flatworms from the North Pacific: Anocellidus n. gen. profundus n. sp. (Anocellidae, n. fam.) and Oligocladus voightae n. sp. (Euryleptidae), pp. 1-19 in Zootaxa 1317 on page 3, DOI: 10.5281/zenodo.17398

Oligocladus voightae Quiroga, Bolaños & Litvaitis, 2006, n. sp.

Species: <i>voightae</i> n. sp. (Figs. 6–10) <p> <i>Type material and locality:</i></p> <p>a) Holotype, whole mount, one mature specimen (12 mm x 10 mm), FMNH 12560, collected 30 August, 2004 from Escanaba Trough, 20 m N of Marker 6X on Central Hill, from 3232 m depth (41° 00.272’N 127° 29.679’W).</p> <p>b) Paratype, one mature specimen as serial sagittal sections (11 mm x 9 mm), FMNH 12464, collected with holotype 30 August, 2004 from Escanaba Trough, 20 m N of Marker 6X on Central Hill, from 3232 m (depth 41° 00.272’N 127° 29.679’W).</p> <p> <i>Distribution:</i> To date, found only at type locality</p> <p> <i>Etymology:</i> Species named in honor of Dr. Janet Voight of the Field Museum of Natural History, Chicago, Illinois.</p> <p> <i>Diagnosis:</i> Mouth anterior to the brain. Eyes, few and minute, scattered on the tentacles. Seminal vesicle connected posteriorly to an auxiliary storage vesicle containing a basophilic substance (possibly sperm). Auxilliary storage vesicle extends dorsally over the seminal vesicle. Posterior anal pore in main median branch of the intestine.</p> <p> <b>Description</b></p> <p> <i>External features:</i></p> <p> <i>Color —</i> preserved animals have a milky white dorsal surface with ovaries appearing as dark brown spots that form a radial pattern. White intestinal branches are visible through the epidermis. The ventral surface is white.</p> <p> <i>Form —</i> oval body shape, margins without folds except for the ones forming the tentacles. The two specimens measured 12mm x 10 mm and 11 mm x 9 mm, respectively. A very conspicuous sucker is located right in the center of the ventral surface, posterior to the pharynx (Figs. 9 and 10).</p> <p> <i>Tentacles —</i> Short (~600 µm), blunt, marginal tentacles formed mainly by the elongation of the body margin rather than the folding of it (Fig. 6).</p> <p> <i>Eyes —</i> Few and minute, scattered over the tentacles. Cerebral and marginal eyes absent.</p> <p> <i>Digestive system —</i> the mouth is a small opening, anterior to the brain (Fig. 8 A). The very muscular and cylindrical pharynx is directed forward and located in the anterior half of the worm, just anterior to the sucker. It folds back on itself in an S­shape, possibly due to a preservation artifact (Figs. 8 A and 10). The pharynx connects to a median intestinal branch which itself extents anteriorly dorsal to the brain, and posteriorly almost to the body margin. The posterior part of the median intestinal branch divides into 6 to 8 large, radial branches and 4 smaller ones just dorsal to the pharynx (Fig. 7). An anal pore is present on the medial intestinal branch just prior to the terminal end of the branch itself (Fig. 7). An anterior vesicle opening to the exterior was observed, but there is no evidence of it being connected or related to the digestive system.</p> <p> <i>Reproductive anatomy:</i></p> <p> <i>Gonopores —</i> pores are well separated from each other. The female pore is posterior to the male pore and located well anterior of the sucker.</p> <p> <i>Male copulatory apparatus —</i> testes are scattered ventrally all over the body but are especially concentrated in the posterior end. The male apparatus is rather small compared to the size of the animal. A free prostatic vesicle (125 µm) is located just dorsal to the male atrium (Fig. 8). The seminal vesicle is larger than the prostatic vesicle (175µm), and is located posterior to the atrium. In addition, the seminal vesicle is connected to an accessory storage vesicle containing a basophilic substance, possibly sperm (Figs. 8 and 10). This accessory vesicle wraps itself dorsally around the seminal vesicle. A deep atrium houses a pointed stylet (175µm).</p> <p> <i>Female copulatory apparatus —</i> The ovaries are dorsal and scattered over the entire body, fanning out in a radial pattern from the pharynx (Fig. 6 A). Two small uterine trunks are present behind the pharynx. Numerous uterine vesicles are present (Figs. 6 A and 9). The female atrium is not very deep and connected to a simple vagina, which in turn connects to oviducts.</p> <p> <b>Taxonomic remarks:</b></p> <p> Both, Faubel (1984a) and Prudhoe (1985) are in agreement of the genus <i>Oligocladus</i> in the Euryleptidae. Therefore, either classification system may be used for its identification. Conspicuous characters such as a digestive system with a median main intestinal branch, a plicate, cylindrical pharynx extending anteriorly to the level of the brain, a male copulatory complex located anterior to the female one, and a true free prostatic vesicle, clearly place this species in the family Euryleptidae. Among the Euryleptidae, three genera share the possession of an anal pore in the main intestinal branch, <i>Oligocladus, Cycloporus,</i> and <i>Leptoteredra.</i> However, only <i>Oligocladus</i> and <i>Cycloporus</i> also possess a pair of uterine trunks with multiple uterine vesicles (Faubel 1984).</p> <p> <i>Oligocladus</i> and <i>Cycloporus</i> are distinguished by the presence of many peripheral vesicles opening to the exterior. In <i>Cycloporus</i> these vesicles have clear connections to the digestive system; in <i>Oligocladus</i> they do not. In one examined specimen, a vesicular channel system opening via several pores to the exterior was observed in the anterior portion, albeit only on one side of the worm. However, the relationship of this channel system to the digestive system is uncertain. In addition, an obvious anal pore opening dorsally from the caudal end of the main intestinal branch confirmed a placement into <i>Oligocladus</i> rather than <i>Cycloporus</i>.</p> <p> Additionally, Hadenfeldt (1929) recognizes the position of the brain posterior to the mouth as unique to the genus <i>Oligocladus</i>, with only two species. According to Faubel (1984), the anatomy of <i>O. auritus</i> is not very well known, although Lang (1884) placed it into this genus because its brain is posterior to the mouth. Thus, the position of the brain of <i>O. voightae</i> supports the placement of this species in the genus <i>Oligocladus</i>. Furthermore, the general anatomy of <i>O. voightae</i> corresponds well with that of <i>O. sanginolentus</i> with the exception of the presence of two sharply­defined clusters of cerebral eyes and an anteriorly trifurcated intestinal trunk in the latter species (Prudhoe, 1985).</p> <p> <b>Ecological remarks:</b></p> <p>It is interesting to note that the two newly described species so far have been collected only from deep­sea wood deployments heavily colonized by wood­boring clams (species of which are currently being described, Dr. J. Voight, Chicago Field Museum, pers. comm.). Previously, Turner (1978) demonstrated the importance of deep­sea wood deployments in the establishment of a highly diverse community, consisting of woodboring bivalves, predatory polychaetes and gastropods, galatheid crabs, echinoderms and most likely fish. With respect to flatworms, Turner (1978) reports a single specimen of a predatory turbellarian only; the most abundant taxa of her study being gastropods and polychaetes.</p> <p>This contrasts sharply with polyclad densities found at Escanaba Trough and ODP. In August 2004, 149 specimens were collected from four 18 inch x 4 inch x 4 inch pieces of lumber at Escanaba Trough that had been deployed there in July 2002, and in July 2003, 47 specimens were collected from ODP 1026B and 33 specimens from near Baby Bare Seamount off identical deployments made in September 2002 (Dr. J. Voight, pers. comm.).</p> <p> The ecological function of the two newly described species may be inferred from known predatory behavior of other polyclads. Acotyleans of the families Leptoplanidae and Stylochidae are known to prey on rock and pearl oysters (Newman <i>et al.</i> 1993, O'Connor & Newman 2001), blue mussels (Galleni <i>et al.</i> 1980, Villalba <i>et al.</i> 1997), barnacles (Murina <i>et al.</i> 1995), and cultured giant clams (Newman <i>et al.</i> 1993). Their impact can be substantial, as they often feed exclusively on spat or juvenile bivalves, resulting in as much as 90% mortality (Newman <i>et al.</i> 1993). Predation by a stylochid polyclad on oysters has been reported also for the US Atlantic and Gulf of Mexico coasts (Provenzano 1961, Webster & Medford 1961, Christensen 1973, Chintala <i>et al.</i> 1993), and Newell <i>et al.</i> (2000) were able to show that small (<5 mm 2) polyclads were instrumental in significantly reducing the numbers of young oyster spat (less than 3 weeks postsettlement) in Chesapeake Bay.</p> <p> Recently, Ritson­Williams <i>et al.</i> (2006) described the predatory behavior of a planocerid, concluding that this flatworm uses tetrodotoxin to capture and kill its mollusk prey. From the observed ecological association of <i>Anocellidus profundus</i> and <i>Oligocladus voightae</i> with deep­sea bivalves, it is tempting to speculate that the flatworms may use a toxin such as tetrodotoxin to subdue their prey. At this point, however, such predator­prey interactions, and the presence of toxins in deep­sea flatworms remain to be demonstrated.</p>Published as part of <i>Quiroga, Sigmer Y., Bolaños, D. Marcela & Litvaitis, Marian K., 2006, First description of deep­sea polyclad flatworms from the North Pacific: Anocellidus n. gen. profundus n. sp. (Anocellidae, n. fam.) and Oligocladus voightae n. sp. (Euryleptidae), pp. 1-19 in Zootaxa 1317</i> on pages 12-17, DOI: <a href="http://zenodo.org/record/173981">10.5281/zenodo.173981</a&gt

Policládidos (Platyhelminthes: â Turbellariaâ ) del Atlántico tropical occidental

-Artículo revisado por pare

Anocellidus Quiroga, Bolaños & Litvaitis, 2006, n. gen.

Genus: <i>Anocellidus</i> n. gen. <p> <i>Definition:</i> with the characters of the family</p>Published as part of <i>Quiroga, Sigmer Y., Bolaños, D. Marcela & Litvaitis, Marian K., 2006, First description of deep­sea polyclad flatworms from the North Pacific: Anocellidus n. gen. profundus n. sp. (Anocellidae, n. fam.) and Oligocladus voightae n. sp. (Euryleptidae), pp. 1-19 in Zootaxa 1317</i> on page 5, DOI: <a href="http://zenodo.org/record/173981">10.5281/zenodo.173981</a&gt