List species and varieties by family
Ryocalanidae Andronov, 1974 ( Ryocalanoidea )
(1) Ryocalanus Tanaka, 1956
Rem.: Brodsky (1980: pers. comm.) indicates that Ryocalanus should be spelled as Riocalanus.
Type: Ryocalanus infelix Tanaka,1956.
Following the redefinition of the genus by Renz & al (2013) the number of species is 4 . Total (2018): 5 spp.

Diagnosis after Renz, Markhaseva & Schulz (2013, p.255) :
- Body length > 1.6 mm.
- Urosome very short.
- Rostrum 1-pointed.
- P1 endopod with proximal inner wedge-shaped projection.
- Male right A1 moderately modified.
- Male P5 uniramous, containing terminal spines on the distal exopod segments.


Key oto species after Boxshall & Halsey (2004, p.184) (modified, Ryocalanus brasilianus not included) :
1- Rostrum simple, tapering to point …….. 2.
1’ – Rostrum bifid …….. other genus (Yrocalanus.
2 - Lateral margins of 5th pedigerous somite rounded ; 1st exopodal segment of male P5 armed with 1 outer spine and ornamented with several fine hair-like setules …….. R. bowmani.
2’ - Lateral margins of 5th pedigerous somite produced into posteriorly directed spinous processes, readily visible in lateral view ……3 ;
3 – 5th pedigerous somite of female ornamented ventrally with 12 long spinules on each side ; Mx1 with 9 setae on coxal epipodite and 4 setae on coxal endite ; female P4 with 9 large robust spinules on posterior surface of coxa …… R. spinifrons.
3’ – 5th pedigerous somite of female ornamented ventrally with row of short spinules on each side ; Mx1 with 6 setae on coxal epipodite and 5 setae on coxal endite ; male P5 without external spine on 1st exopodal segment ……R. infelix.

Nota: The A2 exopod to endopod ratio is 0.82 in R. squamatus (Renz & al., 2018, p.12), while in all other species it is close to 1, a character hypothesized to be diagnostic for the genus Ryocalanus (Renz & al., 2013).

Ryocalanus admirabilis    Andronov, 1992   (F,M)
Rem.: Cf. Yrocalanus admirabilis (Andronov, 1992)

Ryocalanus antarcticus    Renz, Markhaseva & Schulz, 2012   (F,M)
Rem.: Cf. Yrocalanus antarcticus (Renz, Markhaseva & Schulz, 2012)

Ryocalanus asymmetricus    Markhaseva & Ferrari, 1996   (F)
Rem.: Cf. Yrocalanus asymmetricus (Markhaseva & Ferrari, 1996)

Ryocalanus bicornis    Markhaseva & Ferrari, 1996   (F)
Rem.: Cf. Yrocalanus bicornis (Markhaseva & Ferrari, 1996)

[1] Ryocalanus bowmani  Markhaseva & Ferrari, 1996   (M)    [Figs]

[2] Ryocalanus brasilianus  Renz, Markhaseva & Schulz, 2013   (F,M)    [Figs]

[3] Ryocalanus infelix  Tanaka, 1956   (F, M)    [Figs]

[4] Ryocalanus spinifrons  Shimode, Toda & Kikuchi, 2000   (F)    [Figs]

[5] Ryocalanus squamatus  Renz, Markhaseva & Laakmann, 2018   (F,M)    [Figs]
(2) Yrocalanus Renz, Markhaseva & Schulz, 2013
Rem.: Type: Ryocalanus admirabilis Andronov, 1992. Total: 5 spp.
Species included: 4.
Diagnosis after Renz, Markhaseva & Schulz (2013, p.257):
Body length < 1.6 mm.
Urosome relatively long.
Rostrum bifid.
P1 endopod proximal inner part smooth.
Male right geniculated A1 is of highly complex structure.
Male P5 indistinctly biramous with small endopodal buds and with distal exopod segments lacking spines.
Key to species after Boxshall & Halsey (2004, p.184) (modified, Yrocalanus antarcticus not included) :
1- Rostrum simple, tapering to point …….. other genus (Ryocalanus).
1’ – Rostrum bifid …….. 2
2 – Genital double-somite of female strongly asymmetrical in dorsal view …….. Y. asymmetricus.
2’ – Genital double-somite of female more or less symmetrical in dorsal view ……… 3.
3 – Posterolateral angles of 5th pedigerous somite produced posteriorly into pointed lobes …… Y. bicornis.
3’ – Posterolateral angles of 5th pedigerous somite triangular in lateral view : segment 21 of male A1 with 1 long, robust spine on anterior margin ……Y. admirabilis.

[1] Yrocalanus admirabilis  (Andronov, 1992)   (F,M)    [Figs]

[2] Yrocalanus antarcticus  (Renz, Markhaseva & Schulz, 2012)   (F,M)    [Figs]

[3] Yrocalanus asymmetricus  (Markhaseva & Ferrari, 1996)   (F)    [Figs]

[4] Yrocalanus bicornis  (Markhaseva & Ferrari, 1996)   (F)    [Figs]

[5] Yrocalanus kurilensis  Renz, Markhaseva & Laakmann, 2018   (F,M)    [Figs]

 Any use of this site for a publication will be mentioned with the following reference :

Razouls C., Desreumaux N., Kouwenberg J. and de Bovée F., 2005-2022. - Biodiversity of Marine Planktonic Copepods (morphology, geographical distribution and biological data). Sorbonne University, CNRS. Available at http://copepodes.obs-banyuls.fr/en [Accessed July 07, 2022]

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