Amphiscolops Graff, 1905

Ono, Rintaro & Kajihara, Hiroshi, 2025, Description of a new species of Amphiscolops (Xenacoelomorpha: Convolutidae), Journal of Natural History 59 (21 - 24), pp. 1611-1624 : 1614

publication ID

https://doi.org/10.1080/00222933.2025.2489502

persistent identifier

https://treatment.plazi.org/id/03819522-F11C-FFF7-C8B4-FEFACDF78E1A

treatment provided by

Plazi

scientific name

Amphiscolops Graff, 1905
status

 

Amphiscolops Graff, 1905 View in CoL

Emended diagnosis

Coloured through pigment, concrement, symbiotic algae, or combination thereof (absent in A. japonicus ); statocyst usually present (absent in A. oni ); ocelli may be absent; frontal organ present (undetermined in A. mosaicus and A. zeii ); mouth opening ventrally, without pharynx; brain insunk; posterior end rounded, bilobed, or trilobed, without filaments; ovaries and testes usually paired (testis unpaired in A. trifurcatus ); female gonopore absent, or, if present, either single or double ( two female gonopores are positioned on either side of a single male gonopore in A. bermudensis ); single or double male gonopore ventral, subterminal or terminal; two or more curved or corkscrew-shaped sclerotised bursal nozzles; seminal bursa absent, or, if present, either single or double; male copulatory organ conical or tubular, ciliated, glandular, or both; male antrum and seminal vesicle may be absent; prostatoid organ, sagittocyst and caudal penis fold absent.

Composition

The following 10 species are certainly affiliated with the genus Amphiscolops as re-defined above and are clearly distinct from the other convolutid genera: A. bermudensis , A. cinereus , A. fuligineus , A. hamus sp. n. (see below), A. japonicus , A. marinelliensis , A. oni , A. potocani , A. trifurcatus , and A. zeii .

Certain key character states are unknown in the following three species, so they may need to be transferred to one of the other convolutid genera once these features are confirmed in future studies: A. evelinae , A. gemelliporus and A. mosaicus . These species are known only from their original descriptions and have not been thoroughly described; until then, they should be regarded as species inquirendae ( Winsor 1990).

Remarks

The two species A. evelinae and A. gemelliporus were established based on immature specimens ( Marcus 1947, 1954). Since the characteristics of the matured reproductive organs are essential for the acoel taxonomy, the generic affiliation of these species should be assessed in future studies based on adult specimens.

Regarding A. mosaicus View in CoL , its taxonomic position cannot be determined because the following characteristics described by Kozloff (1998) align with both Amphiscolops View in CoL and Heterochaerus View in CoL (cf. Achatz et al. 2010): colouration through zooxanthellae, a statocyst, eyespots, a mouth opening ventrally, a bilobed posterior end, and about 10 nozzles attached with a transversely oval seminal bursa. The primary differences between these genera are the presence of a frontal organ and a caudal penis fold. Concerning the former, Kozloff (1998, p. 16) stated ‘Frontal gland not observed’. Regarding the latter, the ‘small triangular flap’ ( Kozloff 1998, p. 16) covering the male gonopore might correspond to this feature, but its identification remains uncertain.

The genus Amphiscolops View in CoL is distinguishable from the other convolutid genera based on the emended diagnosis. Besides Amphiscolops View in CoL , the three genera Convolutriloba Hendelberg and Åkesson, 1988 View in CoL , Thalassoanaperus Hernández, 2018 View in CoL , and Wulguru Winsor, 1988 View in CoL are the only ones that may possess both a frontal organ and multiple bursal nozzles. Amphiscolops View in CoL differs from Convolutriloba View in CoL by the absence of sagittocysts, from Thalassoanaperus View in CoL by the absence of prostatoid organs, and from Wulguru View in CoL by the absence of a false female gonopore.

Kingdom

Animalia

Phylum

Xenacoelomorpha

Order

Acoela

Family

Convolutidae

Loc

Amphiscolops Graff, 1905

Ono, Rintaro & Kajihara, Hiroshi 2025
2025
Loc

Thalassoanaperus Hernández, 2018

Hernandez 2018
2018
Loc

Thalassoanaperus

Hernandez 2018
2018
Loc

A. mosaicus

Kozloff 1998
1998
Loc

Convolutriloba Hendelberg and Åkesson, 1988

Hendelberg and Akesson 1988
1988
Loc

Wulguru

Winsor 1988
1988
Loc

Convolutriloba

Hendelberg and Akesson 1988
1988
Loc

Wulguru

Winsor 1988
1988
Loc

Amphiscolops

Graff 1905
1905
Loc

Heterochaerus

Haswell 1905
1905
Loc

Amphiscolops

Graff 1905
1905
Loc

Amphiscolops

Graff 1905
1905
Loc

Amphiscolops

Graff 1905
1905
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