Cytherella serratula Brady 1880

Cytherella serratula (Brady, 1880)

(Figs. 9.A–I, 10, Tab. 3)

part 1880 Cythere (?) serratula Brady: 77, Pl. 43.a­d.

non 1896 Cytherella serratula— Brady & Norman: 713­716.

part 1976 Cytherella serratula— Puri & Hulings: 288, Pl. 24.15, 16.

non 1979 Cytherella sp. 11 Ducasse & Peypouquet: 355, Pl. 1.3,4. 1983 Cytherella sp. B Cronin: Pl. 6.E.

non 1985 Cytherella sp. Guernet: 281, Pl. 1.2.

? 1985 Cytherella sp. Guernet: 281, Pl. 1.4.

non 1987 Cytherella serratula— Whatley & Coles: 96, Pl. 6.30, 31.

non 1990 Cytherella serratula— Dingle et al., 254­6, Fig.5.A­C.

? non 1993 Cytherella serratula— Whatley & Arias:283, Pl.1.1.

1996 Cytherella serratula— Aiello et al., Pl. 6.1­4 (S.E.M. photos the lectotype and paralectotype).

non 1996 Cytherella serratula— Coles et al., Pl. 6.14, 15

non 2002 Cytherella serratula— Majoran & Dingle: 149, Pl. 3.20.

non 2006 Cytherella serratula— Bergue et al.: 209.

non 2007 Cytherella serratula— Bergue et al.: 7, Fig.3.

Material. Lectotype: Cythere serratula Brady, 1 RV, contained on the Challenger slide no. 173, labelled “Challenger, No. 24, D. 390, H. S. Puri 9/67, 100”, BMNH cat. no. 80.38.113. The Challenger #24 is located off Culebra Island, West Indies, 390fms (= 713m). This specimen was designated lectotype and described by Puri & Hulings (1976: 288­289, Pl. 24.15­16), also examined and figured by Aiello et al. (1996, pl. 6.2­4). Herein this lectotype is illustrated in Fig. 9.A­D.

Cytherella sp. (BM 80.38.113): H, RV ev; J, posterior ornamentation; I, anterior ornamentation. Scale bars: A, 10µm; B, F, I, J, 100µm, C, E, H, 50µm; D, G, 50µm.

Paralectotype: Cythere? serratula Brady, 1 LV, contained on a second Challenger slide with the same no. 173, labelled “Challenger, No. 24, D. 390, H. S. Puri 9/67, T, 100”, BMNH cat. no. 80.38.113. This specimen was designated paralectotype and described by Puri & Hulings (1976: 288­289), it was also examined and figured by Aiello et al. (1996, pl. 6.1). Herein this paralectotype is illustrated in Fig. 9.E­G.

Distribution. Recent. Off Culebra Island, Northwestern Atlantic, 713m.

V Measurements. Lectotype: RV,?A L 1.10mm, H 0.64mm. Paralectotype LV,?A L 1.08mm, 0.57mm.

Diagnosis. Valve sub­reniform in lateral view, anterior margin more broadly rounded than posterior, ventral margin concave; maximum height anterior to mid­length. Most of lateral surface smooth, except by medio­posterior area with small, sub­conic tubercles. Pore canals simple, without rim. Internally without limen. Flange well developed in LV.

Remarks. The above 15 publications dealing with deep­sea ostracods have figured or cited the occurrence of cytherellid specimens, which were assigned to the supposedly widely distributed species Cytherella serratula (Fig. 10). The total range of all these records would then include slope to abyssal depths in the North and South Atlantic, Mediterranean Sea, Indic and Southern oceans, with a geological record which extends from the Eocene to Recent. As previously stated by Majoran & Dingle (2002), the authors responsible for these records followed “the relatively broad species concept of Cytherella serratula ” (Majoran & Dingle 2002:149). This species concept would then include (Tab. 3, Fig. 10):

Outlines ranging from very elongated (Whatley & Arias 1993) to subquadrate (Dingle et al. 1990); with length / height rations varying from 1.53 to 2.11 in LV and from 1.55 to 1.83 in RV.

Very sinuous (Majoran & Dingle 2002) to continuously and smoothly rounded valve outline (Guernet 1985);

Posterior ornamentation varying from small inconspicuous tubercles (Dingle et al., 1990) to strongly pustulose (Majoran & Dingle 2002);

Anterior valve surface varying from smooth (Dingle et al., 1990) to strongly pustulose (Majoran & Dingle 2002).

Except for the diagnostic characters of the genus Cytherella, the only character uniting all specimens included in C. serratula “ sensu lato ” is the presence of some (highly variable) kind of posterior ornamentation. However, the presence of tubercles or pustules on the posterior surface of valves can not be used as the sole diagnostic character of any Cytherella species, since this ornamentation is present in many other described and well characterized species of the same genus. Examples include: Cytherella cercinata Aiello et al., 1996 (Miocene and Pliocene; Greece and Italy), Cytherella vulgata Ruggieri, 1962 (Miocene; Italy), Cytherella vulgatella Aiello et al., 1996 (Miocene to recent; Mediterranean Sea, Italy and Spain), and Cytherella robusta Colalongo & Pasini, 1980 (Pliocene to recent; Italy, Greece, Mediterranean). Unfortunately, without examining all the material previously analysed by different authors, it is impossible to determine the range of intraspecific variation in the different characters, since most authors illustrate 1 or 2 specimens, and except by Aiello et al., 1996) no micrographs of the ornamentation on different regions of the valve surface are provided.

Study of the present material (C. rwhatleyi sp. nov.) and comparative studies of SEM­photos of deep­sea Cytherella in the literature (Swanson et al. 2005), confirm that the degree of intraspecific variability is much lower than previously thought. The valves of Cytherella rwhatleyi sp. nov. from the 4 different stations (Fig. 3), which are almost 60 of longitude and 10 of latitude apart, display very few intra­ and interpopulational variability. Furthermore, a closer look at the publications on deep­sea ostracods shows that many deep­sea ostracodologists have adopted 2 different ways while defining deep­sea species. In one hand side are the species described in the 19th Century (mostly Brady 1880). For these first species, a very wide intraspecific morphological variability is allowed, most probably because authors are convinced that deep­sea ostracod species are cosmopolitan (Whatley & Ayress 1988), and they expect to find the cosmopolitan taxa in samples from different basins. Furthermore, the illustrations and descriptions provided in the 19th century are so simple that very different specimens may be included in each species. In the other hand side are the species described in the second half of the 20th Century, which are “kept” more or less endemic, (in my opinion) because authors do not expect to find them in localities distant from where they were collected, but also importantly because the SEM illustrations provide much more information, avoiding that too different specimens are assigned to these species.

Consequently, I consider Cytherella serratula (Brady, 1880) to be restricted to bathyal depths of Northwestern Atlantic (Type locality – Brady, 1880, Puri & Hulings 1976, and Aiello et al. 1996; and probably U. S. continental slope—Cronin, 1983). Meanwhile, more subquadrate forms, with larger height / length ratios known from the North Atlantic (Ducasse & Peypouquet 1979, Whatley & Coles 1987, Coles et al. 1996) and Southeastern Atlantic (Dingle et al. 1990), and more elongated forms from Northeastern Atlantic (Brady & Norman 1896), from the Indic Ocean (Guernet 1985) and Mediterranean Sea (Whatley & Arias 1993) should be assigned to different species. Similarly, forms with conspicuously sinuous outline collected from the Indic (Guernet 1985), and the Southern Ocean (Majoran & Dingle 2002) should also be described as different taxa.

Author Locality Age Recent* General RV ­ Length / LV ­ Length / Depth (m) Form height (mm); height (mm) Ratio L/H

......continued on the next page LV

Author Dorsal Mg. Ventral Mg. Ant. Mg. Post. Mg. Max. H. Max. L.

Lectotype (RV) / ­ Paralec­ straight ant.; straight equally narrowly anterior to inferior to mid­height totype (LV) Brady 1880; steeply rounded rounded mid­length Puri & Hulings 1976; inclined post.

Aiello et al 1996 *

......continued LV

Author Dorsal Mg. Ventral Mg. Ant. Mg. Post. Mg. Max. H. Max. L.

Dingle et al 1990 sinuous ant.; slightly con­ equally narrowly posterior to inferior to mid­height

inclined post. cave rounded rounded mid­length

Ducasse & Peypouquet NI NI NI NI NI NI 1979 (as Cytherella sp. 11)

Guernet 1985 straight straight equally narrowly posterior to at mid­height

rounded rounded mid­length

......continued on the next page LV

Author Ornamentation comments

Anterior Posterior

Lectotype (RV) / ­ Paralectotype absent small tuber­

(LV) Brady 1880; Puri & Hul­ cles

ings 1976; Aiello et al 1996 *

Brady & Norman 1896 absent?present The specimens illustrated by Brady & Norman (1896) are conspicuously more

equilateral (with broadly rounded posterior) than the type of C. serratula.

Bergue et al 2006 NI NI Larger height/length ratio than lectotype of C. serratula. Coles et al 1996 present conspicu­ The illustrated specimens are conspicuously higher in relation to length than the

ous small types of C. serratula.

tubercles

Cronin1983?present conspicu­ Cronin (1983) identified the specimens as Cytherella sp. B. Afterwards, Aiello et

ous small al (1996) assigned them to C. robusta Colalongo & Pasini, 1980. Otherwise, Ber­

tubercles gue et al (2007) assigned them to C. serratula.

Dingle et al 1990 present absent (?) or The specimens from the analysed in this publication differ considerably from the

faint (?) type specimens of this species: south Atlantic specimens present (1) more equilat­

eral outline in lateral view; (2) much more faint (or even absence) posterior orna­

mentation; (3) and presence of anterior ornamentation.

Ducasse & Peypouquet 1979 (as NI NI Ducasse & Peypouquet (1979) identified the specimens as Cytherella sp. 11. Cytherella sp. 11) Afterwards, Aiello et al,1996 identified them as C. robusta Colalongo & Pasini,

1980. Otherwise, Bergue et al (2007) assigned them to Cytherella serratula. Guernet 1985 absent conspicu­ The 2 valves illustrated by Guernet (1985) most probably belong to 2 different

ous small species, both of them differing considerably from the lectotypes of C. serratula.

tubercles

Majoran & Dingle 2002 pustulose pustulose The specimens illustrated by Majoran & Dingle (2002, pl. 3.20) present more arc­

uate dorsal margin and concave ventral margin than the lectotype of C. serratula. Whatley & Arias 1993 NI NI The illustrated specimens much more elongated (smaller length / height ratio) then

the lectotype of C. serratula.

Whatley & Coles 1987 NI NI These specimens is heigher in relation to length and present more arcuate dorsal

margin than the lectotype of C. serratula.

1 – Type locality, from Brady (1880) and Puri & Hulings (1976); 2 —from Brady 1880; 3 —from Brady & Norman 1896; 4 —from Ducasse & Peypouquet 1979; 5 – from Cronin 1983; 6 – from Guernet 1985; 7 —from Whatley & Coles, 1987; 8 —from Dingle et al., 1990; 9 —from Whatley & Arias, 1993; 10 —from Coles et al., 1996; 11 —from Majoran & Dingle, 2002; 12 —from Bergue et al. (2007).