Haplogonaria amarilla, Hooge & Eppinger, 2005

Hooge, Matthew D. & Eppinger, Neil, 2005, New species of Acoela (Acoelomorpha) from the Gulf of California, Zootaxa 1009 (1), pp. 1-14: 2-6

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http://doi.org/ 10.11646/zootaxa.1009.1.1

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scientific name

Haplogonaria amarilla

sp. nov.

Haplogonaria amarilla   sp. nov. ( Figs. 1–3 View FIGURE 1 View FIGURE 2 View FIGURE 3 )

Type Material: Holotype. AMNH PLATY 1658, one set of 1.5­µm­thick serial sagittal sections of epoxy­embedded specimens stained with toluidine blue   . Paratypes. AMNH PLATY 1659, one set of 1.5­µm­thick serial sagittal sections of epoxy­embedded specimens stained with toluidine blue, and   AMNH PLATY 1660, epoxy­embedded whole mount   .

Type Locality. San Felipe, Baja California, medium grained sand from a small pool of standing sea water at the high intertidal from the south side of San Felipe Bay (30°58’35.1”N, 114°48’22.6”W) GoogleMaps   .

Other Material Examined. Living specimens in squeeze preparations; three sets of 1.5­µm­thick serial sections of epoxy­embedded specimens; several whole mounts for fluorescence imaging of musculature.

Etymology. Species name is a derivation of the Spanish amarillo, yellow, referring to the species body color.

Description. Mature, living specimens up to 650 µm long and 150 µm wide ( Figs. 1A View FIGURE 1 , 2 View FIGURE 2 ). Preserved specimens contracted to approximately 360 µm long and 140 µm wide ( Figs. 1B View FIGURE 1 , 3 View FIGURE 3 ). Body cylindrical. Anterior and posterior ends rounded. Body color yellow by transmitted light.

Epidermis completely ciliated. Many large rhabdoid glands present; mostly concentrated at anterior end ( Figs. 1 View FIGURE 1 , 2 View FIGURE 2 ).

Musculature with circular muscles that encircle the body along entire length of animal; straight longitudinal muscles present between frontal organ and anterior edge of mouth; longitudinal­cross­over muscles (fibers with a longitudinal orientation anteriorly, but bend medially to cross diagonally) present in both dorsal and ventral body wall; anterior end with ventral diagonal muscles positioned between outer circular and inner longitudinal muscles ( Fig. 3A View FIGURE 3 ).

Frontal organ well developed; cell bodies of frontal glands positioned ~ 100 µm behind frontal pore ( Figs. 1B View FIGURE 1 , 2B View FIGURE 2 ).

Mouth opening on ventral surface, middle of body. Digestive central syncytium extends from posterior end of frontal glands to level of seminal vesicle.

Ovary presumed to be unpaired, ventral; no more than two eggs —positioned medially—discernible in live and sectioned material ( Figs. 1 View FIGURE 1 , 2A, C View FIGURE 2 ).

Testes paired, dorsal, compact; separate from ovary. Testes extend anteriorly to level of mouth and posteriorly to male copulatory organ.

Common gonopore on ventral surface opens anteriorly to sperm­filled seminal vesicle composed of thin layer of muscle and surrounded on ventral and posterior sides by several conspicuous nuclei ( Figs. 1B View FIGURE 1 , 2B View FIGURE 2 , 3B View FIGURE 3 ).

Gonopore opens posteriorly to ill­defined, weak­walled vagina that runs anteriorly over dorsal side of seminal vesicle to sperm­filled seminal bursa; bursa with well­developed bursal wall ( Figs. 1B View FIGURE 1 , 2B View FIGURE 2 ).

Remarks. There are presently 14 described species of Haplogonaria   that are united in having an unpaired ovary, paired testes, and a seminal bursa that lacks a bursal nozzle. Some species, such as H. arenaria (Ax, 1959)   , H. elegans Faubel, 1976   , and H. stradbrokensis Hooge, 2003   have a non­muscular, or weakly muscular seminal vesicle, while other species, such as H. phyllospadicis Hooge & Tyler, 2003   , and H. simplex Dörjes, 1968   , have a strongly muscular seminal vesicle. H. amarilla   is more like the former, with only a very thin layer of muscle contributing to the wall of the seminal vesicle ( Fig. 3B View FIGURE 3 ). It is unusual for members of the Haploposthiidae   to have a vagina positioned as it is in this species; that is, opening posterior to, and passing dorsally over the seminal vesicle. Within the Haplogonaria   , this configuration of the vagina is shared only with H. sinubursalia Dörjes, 1968   . In other regards, the vagina and bursa of H. amarilla   are dissimilar to that of H. sinubursalia   , which has a vagina filled with granular secretions (vesicula granulorum), and a bursa bearing a cap of cells on its proximal wall; both of these features are lacking in H. amarilla   .


American Museum of Natural History