Neoasterocheres , Canário, Roberta, Rocha, Carlos Eduardo Falavigna Da, Neves, Elizabeth & Johnsson, Rodrigo, 2017

Canário, Roberta, Rocha, Carlos Eduardo Falavigna Da, Neves, Elizabeth & Johnsson, Rodrigo, 2017, A new asterocherid genus (Copepoda: Siphonostomatoida) associated with Callyspongia Duchassaing & Michelotti and reassessment of six species of Asterocheres Boeck, Zootaxa 4247 (2), pp. 101-113: 102-104

publication ID

https://doi.org/10.11646/zootaxa.4247.2.1

publication LSID

lsid:zoobank.org:pub:CCCF3891-8DD8-4AB6-87FA-43DEC651BC20

persistent identifier

http://treatment.plazi.org/id/03CA441B-361C-FF8C-9DF4-F908FBF8FB87

treatment provided by

Plazi

scientific name

Neoasterocheres
status

gen. nov.

Neoasterocheres  gen. nov.

Diagnosis. Asterocheridae  . Body dorsoventrally flattened. Prosome ovoid or discoid, urosome cylindrical and 4- segmented in female. Antennule of female basically 19-segmented with large aesthetasc on 17th segment; ancestral segments IX –XIII fused; distal 3 segments frequently fused to become 1 or 2 segments. Antenna with 1-segmented exopod and 3-segmented endopod bearing distal claw. Oral cone short or elongated, siphon-like. Mandible consisting of stylet and 1- or 2-segmented palp bearing two distal setae. Maxillule bilobed. Maxilla 2-segmented; distal segment forming curved claw. Maxilliped with 6-segmented. Legs 1–4 with 3-segmented exopod and endopod. Free segment of leg 5 with 2 or 3 setae.

Remarks. Kim (2010) proposed a new definition for Asterocheres  , with the main diagnostics characters related to leg setation and number of antennule segments posteriorly to aesthetasc. Thus, the author restricted the number of valid species in Asterocheres  and many species were considered as species inquirendae. Since then, new species of Asterocheres  were described ( Crescenti et al. 2010; Varela 2010, 2012; Kim & Min 2013) and redescriptions were published ( Conradi & Bandera 2011; Bandera & Conradi 2013; Bandera & Conradi 2014). Although the new species being described shows the leg setation established by Kim for Asterocheres  , the antennule segmentation highlights a relevant difference in the fusion pattern. Neoasterocheres  gen. nov. can be distinguished from Asterocheres  by having the fusion of antennule ancestral segments IX –XIII resulting in the aesthetasc located on the 17th segment, with 3 distal segments frequently fused to become 1 or 2. Kim (2010) stated that the female antennule is basically 21-segmented because depending on the existence of distal fusions the amount of segments can be reduced to 19, however these fusions occurs between the last 3 segments, which are posterior to ancestral segment XXI. When Kim (2010) established that the aesthetasc is located on segment 18 in Asterocheres  , the author excluded the possibility of occurrence of other additional fusions previous to the 18th segment, and disregarded the existence of species presenting fusions of additional ancestral segments.

According to Huys & Boxshall (1991) on the ancestral pattern of a siphonostome antennule, segment XXI is characterized by the presence of an aesthetasc additional to the maximum armature of two setae found in an unfused segment. Therefore, the authors highlighted the presence of a group of setae on ancestral segment IX, thus indicating a fusion involving at least segments IX –XII. This is expressed in a maximum of 8 setae present on the segment and the existence of eight free single segments between this compound segment (IX –XII) and the one bearing the aesthetasc (XXI). The presence of less than eight free segments between these two landmarks indicates the occurrence of further fusions in the section. Besides that, a spine is commonly present on ancestral segment XIV, and may constitute another relevant landmark. In Asterocheres  we found a segment between the compound segment (IX –XII) and the segment bearing a spine (XIV), thus indicating that ancestral XIII segment is free. In the new genus the segment with a spine (XIV) is close to the compound segment (IX –XII). The ancestral segment XIII is not free, it is fused with the previous segment (IX –XII). This pattern can be confirmed by the existence of only seven free segments between the original IX –XII and the XXI, and by the absence of any double segment between these two landmarks, which would be indicated by the presence of four setae and a segment with a length twice its regular size.

In addition, the new genus shows characters that differ from the remaining asterocherid genera. Bythocheres Humes, 1998  , Cheramomyzon Humes, 1989  , Collocheres Canu, 1893  , Collocherides Stock, 1971  , Dermatomyzon Claus, 1889  , Discopontius Nicholls, 1944  , Gerulusosacculus Ivanenko & Defaye, 2004  , Glyptocheres Humes, 1987  , Ophiurocheres Humes, 1998  , Meandromyzon Stock, 1989  , Rhyncomyzon Giesbrecht, 1895 and Thermocheres Kim, 2010  share an urosomite with 3 post-genital urosomites in the female ( Claus 1889; Canu 1893; Giesbrecht 1895; Nicholls 1944; Stock 1971, 1989; Humes 1987, 1988, 1989, 1998; Ivanenko & Defaye 2004; Kim 2010) instead of two as observed in the new genus. The tergites of the third pedigerous somite are not expanded posteriorly over rest of prosome in Neoasterocheres  gen. nov. as it is seen in Phyllocheres ( Humes 1996b)  . Both Discopontius Nicholls, 1944  and Meandromyzon coronatum Stock, 1989  have 2 post-genital segments like Neoasterocheres  n. gen., but Discopontius  has a 2-segmented P4 endopod and M. coronatum  has a 1- segmented mandibular palp, both characters diverging from those observed in Neoasterocheres  n. sp. ( Nicholls 1944, Stock 1989).

Chelacheres  has a claw-like element distally on the antennary endopod ( Stock & Humes 1995), which is absent in the new genus. Neoasterocheres  gen. nov. differs from Cephalocheres Kim, 2010  , Humesimyzon Kim, 2010  and Mimacheres Leigh-Sharpe, 1934  once it does not show reduction or absence of the antennary exopod to a single seta ( Leigh-Sharpe 1934; Kim 2010) or the 2-segmented condition as described in Humescheres Kim, 2005 ( Kim 2005)  . The mandibular palp is 1-segmented or absent in Asteropontella Stock, 1989  , Asteropontius Thompson & Scott, 1903  , Asteropontopsis Stock, 1987  , Gascardama Kim, 2010  , Hetairosyna Humes, 1991  , Hetairosynopsis Humes, 1996  and Stenomyzon Kim, 2010  ( Thompson & Scott 1903; Stock 1987, 1989; Humes 1991, 1996a; Kim 2010) and 2-segmented with 1 seta in Parasterocheres Humes, 1996 ( Humes 1996b)  while a 2- segmented palp with 2 distal setae is found in Neoasterocheres  gen. nov. Hetairosynella Kim, 2010  possesses five setae on the inner maxillulary lobe ( Kim 2010) instead of four as in Neoasterocheres  n. gen. Stockmyzon Bandera & Huys, 2008  shows a five-segmented maxilliped ( Bandera & Huys 2008) differencing from Neoasterocheres  gen. nov. The new genus can also be distinguished by its possession of a biramous P4 with 3-segmented exopod and endopod. This condition diverges from Cletopontius Thompson & Scott, 1903  , Cyclocheres Kim, 2010  , Cystomyzon Stock, 1981  , Discopontius Nicholls, 1944  , Kolocheres Johnsson, 1999  , Obesiella Ridewood, 1903  , Oedomyzon Stock, 1981  , Peltomyzon Stock, 1975  , Siphonopontius Malt, 1991  and Tuphacheres Stock, 1965  ( Ridewood 1903; Thompson & Scott 1903; Nicholls 1944; Stock 1965, 1975a, 1981; Malt 1991; Johnsson 1999a; Kim 2010). In addition, Neoasterocheres  gen. nov. has two inner setae on the second endopodal segments of all legs, thus diverging from Cecidomyzon Stock, 1981  , Gomumucheres Humes, 1996  , Hermacheres Stock, 1987  , Indomyzon Ummerkutty, 1966  , Inermocheres Boxshall, 1990  , Onychocheres Stock & Gooding, 1986  , Psilomyzon Stock, 1965  , Scottocheres Giesbrecht, 1897  , Sinopontius Giesbrecht, 1897  and Tychomyzon Humes, 1991  , all with the second endopodal segments of at least one leg armed with one inner seta ( Giesbrecht 1897; Ummerkutty 1966; Stock & Gooding 1986; Boxshall 1990; Humes 1991, 1996b; Stock, 1965, 1975a, 1981, 1987). Neoasterocheres  gen. nov. differs from Acontiophorus Brady, 1880  , Asterocheroides Malt, 1991  , Asteropontoides Stock, 1975  , Hammatimyzon Stock, 1981  , Mesocheres Norman & Scott, 1905  , Orecturus Humes, 1992  , Paracontiophorus Eiselt, 1961  and Parasteropontius Johnsson, 1999  by carrying five elements on the third endopodal segment of leg 4 ( Brady 1880; Norman & Scott 1905; Eiselt 1961; Stock 1975b, 1981; Malt 1991; Humes 1992; Johnsson 1999b). Laperocheres Ivanenko, 1999  lacks an inner seta on the first exopodal segment of legs 1–4 ( Ivanenko 1999) while these setae are present in Neoasterocheres  gen. nov. Neoasterocheres  gen. nov. can be distinguished from Monocheres Stock, 1966  by the presence of a free one-segment of leg 5 ( Stock 1966a) and additionally differs from Doropontius Thompson & Scott, 1903  which possess a two-segmented leg 5 ( Thompson & Scott 1903).

Further, some of the species treated as valid Asterocheres  by Kim (2010) share the antennulary fusion pattern herein defined as belonging to Neoasterocheres  gen. nov. So, we propose that six species, i.e., A. enewetakensis Humes, 1997  , A. dysideae Humes, 1996  , A. rotundus Malt, 1991  , A. scutatus Stock, 1966  and A. serrulatus (Humes, 1996)  are transferred to the new genus. Asterocheres humesi Varela, 2012  was described posteriorly to Kim ´s work and also have this fusion pattern in the antennule ( Varela 2012) and should be in Neoasterocheres  gen. nov.

Etymology. The name ‘ Neoasterocheres  ’ is a combination of ‘neo’ (from the Greek adjective meaning ‘new’) and Asterocheres  , referring to the similarities between the new genus and its congener.

Type species by original designation: Neoasterocheres breviseta  sp. nov.

Kingdom

Animalia

Phylum

Arthropoda

Class

Maxillopoda

Order

Siphonostomatoida

Family

Asterocheridae

Loc

Neoasterocheres

Canário, Roberta, Rocha, Carlos Eduardo Falavigna Da, Neves, Elizabeth & Johnsson, Rodrigo 2017
2017
Loc

Asterocheres humesi

Varela 2012
2012
Loc

Cephalocheres

Kim 2010
2010
Loc

Humesimyzon

Kim 2010
2010
Loc

Gascardama

Kim 2010
2010
Loc

Stenomyzon

Kim 2010
2010
Loc

Hetairosynella

Kim 2010
2010
Loc

Cyclocheres

Kim 2010
2010
Loc

Stockmyzon

Bandera & Huys 2008
2008
Loc

Humescheres Kim, 2005 ( Kim 2005 )

Kim, 2005 (Kim 2005
2005
Loc

Kolocheres

Johnsson 1999
1999
Loc

Parasteropontius

Johnsson 1999
1999
Loc

Laperocheres

Ivanenko 1999
1999
Loc

A. enewetakensis

Humes 1997
1997
Loc

Hetairosynopsis

Humes 1996
1996
Loc

Parasterocheres Humes, 1996 ( Humes 1996b )

Humes, 1996 (Humes 1996
1996
Loc

Gomumucheres

Humes 1996
1996
Loc

A. dysideae

Humes 1996
1996
Loc

A. serrulatus

Humes 1996
1996
Loc

Orecturus

Humes 1992
1992
Loc

Hetairosyna

Humes 1991
1991
Loc

Siphonopontius

Malt 1991
1991
Loc

Tychomyzon

Humes 1991
1991
Loc

Asterocheroides

Malt 1991
1991
Loc

A. rotundus

Malt 1991
1991
Loc

Inermocheres

Boxshall 1990
1990
Loc

Asteropontella

Stock 1989
1989
Loc

Asteropontopsis

Stock 1987
1987
Loc

Hermacheres

Stock 1987
1987
Loc

Onychocheres

Stock & Gooding 1986
1986
Loc

Cystomyzon

Stock 1981
1981
Loc

Oedomyzon

Stock 1981
1981
Loc

Cecidomyzon

Stock 1981
1981
Loc

Hammatimyzon

Stock 1981
1981
Loc

Peltomyzon

Stock 1975
1975
Loc

Asteropontoides

Stock 1975
1975
Loc

Indomyzon

Ummerkutty 1966
1966
Loc

Monocheres

Stock 1966
1966
Loc

A. scutatus

Stock 1966
1966
Loc

Tuphacheres

Stock 1965
1965
Loc

Psilomyzon

Stock 1965
1965
Loc

Paracontiophorus

Eiselt 1961
1961
Loc

Discopontius

Nicholls 1944
1944
Loc

Mimacheres

Leigh-Sharpe 1934
1934
Loc

Mesocheres

Norman & Scott 1905
1905
Loc

Asteropontius

Thompson & Scott 1903
1903
Loc

Cletopontius

Thompson & Scott 1903
1903
Loc

Obesiella

Ridewood 1903
1903
Loc

Doropontius

Thompson & Scott 1903
1903
Loc

Scottocheres

Giesbrecht 1897
1897
Loc

Sinopontius

Giesbrecht 1897
1897
Loc

Acontiophorus

Brady 1880
1880