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

publication ID	https://doi.org/ 10.11646/zootaxa.1009.1.1
publication LSID	lsid:zoobank.org:pub:5196FC91-19DF-4B33-8DCB-F7F0984E784A
DOI	https://doi.org/10.5281/zenodo.5048868
persistent identifier	https://treatment.plazi.org/id/5E2E87CB-DA7C-FFC3-2152-10E033DCFC51
treatment provided by	Felipe
scientific name	Haplogonaria amarilla
status	sp. nov.

Treatment

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 .