Armatoplana colombiana, Bolaños & Quiroga & Litvaitis, 2006

Bolaños, D. Marcela, Quiroga, Sigmer Y. & Litvaitis, Marian K., 2006, A new acotylean flatworm, Armatoplana colombiana n. sp. (Platyhelminthes: Polycladida: Stylochoplanidae) from the Caribbean coast of Colombia, South America, Zootaxa 1162, pp. 53-64 : 55-60

Armatoplana colombiana n. sp.

( Figs. 1–9 )

Type material

Holotype, one mature specimen (5.5 mm X 3 mm) in 70% ethanol, INV­PLA 0019 ; collected in August 2002.

Paratype, one mature specimen (6 mm x 2.5 mm) as serial sagittal sections, INV­PLA 0020 HS, collected in August 2002.

Other Material Examined: one additional mature specimen (6 mm x 3 mm); reproductive system sectioned sagittally.

Type Locality: Inca­Inca (N11° 11’; W74° 14’), Gaira Bay, 6 km southeast of Santa Marta, Colombia.

Etymology Species name refers to Colombia, the country from which the type specimens were collected.

Synonyms Pleioplana sp. Bolaños et al., 2004. Pleioplana sp. Quiroga et al., 2004.

Distribution To date, found only at Inca­Inca Bay, Tayrona National Park, Santa Marta, Colombia, from under rocks in the littoral zone.

Diagnosis

Species characterized by non­retractile nuchal tentacles and by 6–8 submarginal knobs at the anterior end. Male stylet extremely long (1250–1500 µm), curved, with very pointed end.

Description

External features: Small worms, of light grayish color, with dorsal surface covered with an irregular distribution of brown spots ( Fig. 1 ). Anterior end rounded and bearing 6–8 fleshy, well­separated knobs ( Figs. 2 , 3 , and 5). Short (200 µm long), non­retractile nuchal tentacles present just lateral to the brain ( Figs. 2 , 4 and 5 ). Small eyes scattered at the base of the tentacles and in the cerebral region as three eye clusters. Ruffled pharynx centrally located in anterior third of body, mouth at posterior end of pharynx. Uteri visible through body wall, running anterior, anastomosing just above the anterior end of the pharynx. Male and female gonopores separate and posterior to pharynx. Anterior and posterior heavy concentration of rhabdites in epidermis. Posterior end pointed.

Reproductive anatomy: Measurements refer to lengths in a 4.3 mm long worm. Male copulatory apparatus located anterior to male pore and directed posteriorly. Very deep, male antrum houses a long (1250 x 50 µm) and curved stylet, stylet curves dorsally over the seminal and prostatic vesicles. In the majority of fixed worms, the stylet is extruded from the male pore ( Fig. 5 ). Prostatic vesicle (275 x 225 µm) interpolated, seminal vesicle (275 x 175 µm) joined dorsally to prostatic vesicle ( Fig. 9 ). Both seminal and prostatic vesicles with strongly muscularized walls. Prostatic and seminal vesicles very close to each other, hence it is very difficult to distinguish between them. Prostatic vesicle slightly curved, joined almost directly to the stylet. Testes ventral ( Fig. 6 ); highly sinuous vasa deferentia ( Fig. 7 ) joined dorsally to seminal vesicle. Female reproductive system with very sinuous vagina with ridged walls ( Fig. 8 ); Lang’s vesicle present. Uteri highly voluminous. Male gonopore close to female pore. A schematic representation of the reproductive complex is given in Fig. 9 .

Taxonomic Remarks

Bock’s (1913) seminal work on the Polycladida divided the Acotylea into three sections based mostly on the arrangement of the eyes, namely the Emprosthommata, Craspedommata, and Schematommata. Prudhoe (1982) in turn, emended these divisions into three superfamilies, the Cestoplanoidea, Stylochoidea, and Planoceroidea, respectively. Using mostly characters of the male reproductive system, Faubel (1984) revised the three superfamilies to Ilyplanoidea (true prostatic vesicle lacking), the Stylochoidea (prostatic vesicle free), and the Leptoplanoidea (prostatic vesicle interpolated), respectively ( Table 1 ; see also Tyler et al. 2005). Within the Leptoplanoidea, Faubel (1984) established three new families, one of which, the Stylochoplanidae , he validates with the characters “true prostatic vesicle present, its glandular lining smooth and the glands of which mostly extravesicular.”

Within this family, the genus Stylochoplana ( Stimpson 1857) consists of a heterogeneous assemblage of numerous species. Recognizing the need for a more appropriate classification, Marcus & Marcus (1968) had separated the genus into groups based on presence or absence of tentacles and of a stylet. Their group C2, characterized by the presence of tentacles and an armed penis, contains three species, S. divae , S. vesiculata , and S. evelinae ( Marcus & Marcus 1968) .

Since then, Faubel (1983) erected the genus Armatoplana , including those species of Stylochoplana characterized by an armed penis and the presence of Lang’s vesicle. Species with an unarmed conical penis papilla were retained in Stylochoplana . Faubel (1983) distinguishes species of Armatoplana from species in other genera of the family by the following combination of characters: lack of tentacles, presence of serial cerebral and tentacular eyes, an anteriorly located pharynx, presence of a true seminal vesicle or spermiducal bulbs, and an armed penis with a long, sharp stylet. Lang’s vesicle and a true vagina bulbosa are present in the female copulatory apparatus. However, the character “presence/absence of nuchal tentacles” may be of little systematic value, because Faubel (1983) moved two species with head tentacles, S. divae and S. vesiculata of group C2 ( Marcus & Marcus 1968) into Armatoplana . Based on this, we believe it is appropriate to emend Armatoplana to include worms with or without nuchal tentacles. This is further supported by the fact that nuchal tentacles may be difficult to discern in poorly fixed material and may have been overlooked in the past.

With the exception of the presence of nuchal tentacles in our specimens, the newly described species Armatoplana colombiana , agrees with all the characteristics of the genus as defined by Faubel (1983). However, as stated above, the presence of tentacles may not be of great taxonomic significance. Initial identifications that had placed this species into the genus Pleioplana were based mostly on a general arrangement of reproductive structures and the presence of a long, pointed stylet ( Bolaños et al. 2004, Quiroga et al. 2004). Since then, it has become clear that the prostatic vesicle of Pleioplana , containing well­defined tubular chambers, is very different from the prostatic vesicle observed in our specimens. The only other genus within the Stylochoplanidae that is characterized by an armed penis, the presence of Lang’s vesicle and tentacles is Interplana . However, in species of Interplana , the stylet does not curve dorsally over the prostatic and seminal vesicles as it does in species of Armatoplana .

The presence of anterior marginal knobs ( Figs. 2 , 3 and 5 ) which are lacking in A. divae and A. vesiculata , clearly separates A. colombiana from these congenerics, as do differences in reproductive system structures, i.e., A. colombiana has a much longer and more curved stylet, the prostatic vesicle is more rounded, and Lang’s vesicle is bigger (Table 2). In addition, no mature specimens of A. divae and A. vesiculata are known that are less than 1cm in length.

The shape and nature of the male reproductive systems of A. lactoalba , A. leptalea , and A. panamensis show close similarities with those of A. colombiana . However, based on the presence of tentacles and marginal anterior knobs in A. colombiana , the new species can be reliably separated from these three species (Table 2). Additionally, coloration and size can be used to differentiate among these species. Finally, live specimens of A. colombiana may be confused with Styloplanocera fasciata because coloration and color patterns (light grey with isolated dark brown spots and a network of brown pigmentation covering the dorsal surface) of the two are almost identical. However, a closer examination of S. fasciata will show that knobs are present all over its surface, whereas they are limited to the anterior end in A. colombiana . Additionally, S. fasciata of such a small size would not be mature individuals. Internally, of course, the male reproductive systems of S. fasciata and A. colombiana are completely different, again emphasizing the importance of histological sections for positive species identifications in Acotylea.

Acknowledgements

We thank Nestor E. Ardila for helpful advice, and INVEMAR for logistic support and the curation of types. This work was supported in part by NSF grant DEB0412932, and is Scientific Contribution No. 2291 from the New Hampshire Agricultural Experiment Station.

Figures

FIGURE 1. Whole, fixed animal, representing general body shape and nuchal tentacles.

FIGURE 2. Fleshy, anteriorly located knobs (white arrow heads) and nuchal tentacles (black arrows).

FIGURE 3. Sagittal section through the anterior end, indicating position of knobs (arrow); the anterior end is folded subterminally. Scale = 1 mm.

FIGURE 4. Sagittal section with nuchal tentacles (arrows). Scale = 1 mm.

FIGURE 5. Sagittal section showing one anterior knob, tentacle, ovaries, Lang’s vesicle, and distal point of extruded stylet. Scale = 1 mm.

FIGURE 6. Sagittal section showing ventral location of testes. Scale = 1 mm.

FIGURE 7. Sagittal section displaying anterior brain capsule, voluminous pharynx, and highly sinuous vasa deferentia. Scale = 1 mm.

FIGURE 8. Sagittal section showing prostatic and seminal vesicles, sinuous vagina, and cement glands. Scale = 250 µm.

FIGURE 9. Diagrammatic representation of copulatory complex of A. colombiana. Scale = 250 µm.

Tables

TABLE 1. Comparison of the changing nomenclature of the three acotylean superfamilies.

Authority	Superfamily	Superfamily	Superfamily
Bock 1913	Craspedommata	Schematommata	Emprosthommata
Poche 1926	Stylochoidea	Planoceroidea	Cestoplanoidea
Marcus & Marcus 1966	Craspedommatidea	Schematommatidea	Emprosthommatidea
Prudhoe 1982	Stylochoidea	Planoceroidea	Cestoplanoidea
Faubel 1983	Craspedommatidea	Schematommatidea	Emprosthommatidea
Faubel 1984	Stylochoidea	Leptoplanoidea	Ilyplanoidea
Tyler et al. (2005)	Stylochoidea	Leptoplanoidea	Ilyplanoidea