A new genus and new species of stygobitic copepod (Crustacea: Copepoda: Cyclopoida) from Thien Duong Cave in Central Vietnam, with a redescription of Bryocyclops anninae (Menzel, 1926) Author Sanoamuang, La-orsri Author Boonyanusith, Chaichat Author Brancelj, Anton text Raffles Bulletin of Zoology 2019 2019-04-02 67 189 205 journal article 10.26107/RBZ-2019-0016 2345-7600 4575785 A3338D70-93CD-41CD-A81D-CDFF4AD964AD Pseudograeteriella , new genus Diagnosis. Small Cyclopinae with slightly elongated habitus and greatest width at posterior margin of cephalothorax. Antennule 11-segmented in female, and 15-segmented in male. Female A1 short, hardly reaching posterior margin of cephalosome. Genital double-somite as long as wide, incision between anterior and posterior half of segment moderate. Seminal receptacle well developed; anterior expansion wide, short; posterior expansion well developed, longer than anterior expansion. P5 with protopodal segment incorporated into Pd5, lacking outer basal seta; exopodal segment fused to Pd5, with one spine apically and one plumose seta dorsally, similar in length. P 6 in female small semicircular plate, armed with two short spines. Anal operculum short, broadly rounded, free margin smooth. Basis of antenna without seta representing Exp. Mandibular palp with two very long plumose setae and one short, bare. Coxae of P1–P3 with plumose seta on inner corner, but absent on P4. P1–P4 with 2-segmented Exp and Endp, similar in length. Spine and setae formula on terminal segments of Exp P1–P4 observed to be 3.3.3.3 and 5.5.5.4, respectively. Male genital somite as long as wide. Table 1. Differences between genera Graeteriella Brehm, 1926 (including subgenera Graeteriella Brehm, 1926 and Paragraeteriella Rylov, 1948 ) and Pseudograeteriella new genus .

Character	Graeteriella Brehm, 1926	Pseudograeteriella new genus
Length of antennule	Middle of cephalosome	Close to end of cephalosome
Receptaculum seminis	Anterior part wide, well developed; posterior part reduced/absent	Anterior part wide, short; posterior part long, well developed
Female: No. of segments P1–P4 Exp/Endp	Graeteriella s.str. : 2.2/2.2/2.2/2.2 Paragraeteriella : 2.2/3.2/3.3/3.3	2.2/2.2/2.2/2.2
Inner seta on basis of P4	Present	Absent
P5 Endp	Separated from pediger	Fused with pediger
P5 spine: seta length	1: 3–4	1: 1–1.2
Fu width: length	1: 1.5–3	1: 5–6

Type species. Pseudograeteriella longifurcata ( Tran & Chang, 2013 ) ; Syn: Graeteriella ( Graeteriella ) longifurcata Tran & Chang, 2013 ; by present designation. Etymology. The genus name is composed of the Latin preposition “ pseudo ” (meaning “false”) and the existing generic name Graeteriella . The gender is feminine. Remarks. To date, only four genera within the subfamily Cyclopinae Burmeister, 1834 have been identified with the absence of outer basal seta on the protopodal segment of P5 ( Dussart & Defaye, 2001 ). Two of those have only one element representing P5. In Bacillocyclops Lindberg, 1956 , P5 is reduced to a short, thick, weakly barbed appendix; whereas, P5 is reduced to a tiny, slender seta in Austriocyclops Kiefer, 1964 ( Dussart & Defaye, 2001 ). Two elements on P5 End are present in Graeteriella Brehm, 1926 [with subgenera Graeteriella s. str. Brehm, 1926 and Paragraeteriella Rylov, 1948 (1963) ( Dussart, 1969 )] and Pseudograeteriella new genus . Both genera differ in the characters presented in Table 1 . Boonyanusith et al. (2018) considered the species from Vietnam and Europe as the members of a single genus, Graeteriella , separated into two subgenera. However, our new findings and the data that we report herein suggest that two clearly distinct genera exist: Graeteriella from Europe and Pseudograeteriella , new genus , from Asia ( Vietnam ). Accordingly, the following amendment should be made to the key in Boonyanusith et al. (2018: 23) , where paragraph “7” should be modified and a new paragraph “7a” to be added, as follows: 7. Pd5 without lateral seta (vestige of the basis of P5) ........... 7a – Pd5 with lateral seta................................................................9 7a. P5 with distal segment fused to Pd5; with two setae/spines apically...................................... Pseudograeteriella new genus – P5 with one free distal segment on Pd5; with two setae/spines apically............................................................. Graeteriella (8) Similarities: P 6 in male and female are similar in shape and size in both Graeteriella and Pseudograeteriella , new genus . Conclusions: Pseudograeteriella , new genus , is the older lineage of the two genera based on reductions of inner seta on basis of P4, and fusion of P5 Endp with pediger.