Taurocletodes, AND GENERIC DIAGNOSES

Karaytuǧ, Süphan & Huys, Rony, 2004, Taxonomic position of and generic distinction between Parepactophanes Kunz, 1935 and Taurocletodes Kunz, 1975 (Copepoda, Canthocamptidae incertae sedis), with description of a new species from the Black Sea, Zoological Journal of the Linnean Society 140 (4), pp. 469-486 : 482

VALIDITY OF TAUROCLETODES AND GENERIC DIAGNOSES

Proper comparison between the type species P. minuta and the material variously identified or named as P.? dubia , T. gallicus or P. dubia has until now been hampered by the fragmentary nature of the corresponding (re)descriptions or the unavailability of either males ( Noodt, 1958b) or females ( Kunz, 1975). Consequently, the issue whether the respective type species of Parepactophanes and Taurocletodes are congeneric ( Kunz, 1983), has not been satisfactorily addressed. The description of both sexes of T. tumenae now enables us to subject the proposed synonymy of Parepactophanes and Taurocletodes to more scrutiny. Although Noodt (1958b) identified Parepactophanes as the closest match for P.? dubia , it is obvious that he intended only provisional generic assignment. Amongst other, less significant, features he recognized the 3-segmented P1 endopod in the Tenerife material as the major stumbling block to its inclusion in Parepactophanes , since both the type species P. minuta and the allegedly most closely related genera ( Cletocamptus , Limnocletodes Borutzky ) exhibit the 2-segmented condition.

Parepactophanes minuta has not been redescribed since Kunz’ (1935) original description, which omitted illustrations of the mouthparts but was otherwise sufficiently informative by contemporary standards. Using Kunz’ (1935) illustrations as the basis for comparison with T. tumenae we believe that there are sufficient grounds to maintain the generic distinction between Parepactophanes and Taurocletodes . Most diagnostic characters readily emerge from a comparison of the swimming legs. We have no reason to doubt the accuracy of Kunz’ observations of the swimming legs since Noodt, who was generally more detailed in his approach and identified P. minuta on more than one occasion ( Noodt, 1956, 1957, 1958a), would undoubtedly have reported oversights or ambiguities in the original description when attempting to overcome the difficulties in placing P.? dubia .

The P1 endopod in Parepactophanes is as long as the exopod, 2-segmented, displays a [1.111] armature formula and lacks penicillate setae on the distal segment. In Taurocletodes it is distinctly longer than the exopod, 3-segmented, exhibiting a formula [1.1.111] with the inner seta on the middle and distal segments clearly penicillate in nature ( Figs 5A,B , 9A ) (for absence of these setae in Kunz’ (1975) description of T. gallicus , see below). The distal exopod segment of P2–P4 has two outer spines in Taurocletodes but this number is reduced to one in Parepactophanes . In addition, P. minuta possesses an inner seta on P4 exp-3, which is lacking in all Taurocletodes species. Males of both genera can be readily distinguished by the sexual dimorphism on the P2–P3 exopods, being completely absent in Parepactophanes , but clearly expressed in the outer spine of the proximal segment in Taurocletodes . This modification is moderate in P2, involving modest size increase of the spine and loss of surface ornamentation ( Fig. 5C, D ). It attains extreme proportions on the proximal exopod segment of P3 where the massive spine arises from a distinct pedestal, formed by the outer portion of the segment, and reaches to halfway along the distal segment ( Fig. 6B,C ).

Both genera also differ in the segmentation and sexual dimorphism of the P2–P3 endopods. In P. minuta the endopods are 1-segmented and that of the P2 not sexually dimorphic. In Taurocletodes both endopods are 2-segmented but the inner seta on enp-1 found in the female P2 (and corresponding to the inner seta of the 1-segmented endopod of Parepactophanes ) is absent in males. The sexual dimorphism of the P3 endopod is similar in both genera although the fine details of segmentation and ornamentation are not discernible in Kunz’ drawings of P. minuta . The distal portion of the male P3 endopod appears to extend into an apophysis and the inner seta present in the female is lost in the male (as in Taurocletodes ; Fig. 6B,D ).

Finally, in Parepactophanes the rostrum is short and blunt, and the female P5 baseoendopod bears two spines and two setae. In Taurocletodes , the rostrum is long and spatulate ( Figs 3A , 4A ) and the endopodal lobe of the female P5 carries four setiform elements ( Fig. 5E ).

On the basis of the suite of generic diagnostics identified above we refute Kunz’ (1983) course of action to relegate Taurocletodes to a junior synonym of Parepactophanes , and instead re-instate the former as a valid genus, with T. dubius (Noodt, 1958) comb. nov. as its type species. Amended generic diagnoses for both genera are given below.

Figures

Figure 3. Taurocletodes tumenae sp. nov. Female. A, rostrum and proximal segments of left antennule, dorsal. B, antennule, anterior. C, antenna, outer lateral. D, antennary endopod, medial. E, mandible. F, mandibular gnathobase. G, maxillule, posterior. H, maxilliped.

Figure 4. Taurocletodes tumenae sp. nov. A, rostrum and right antennule ♂, dorsal (for complete armature of segments 3–4 see B). B, antennule ♂, segments 3–10, ventral. C, maxilla (inset showing distal syncoxal endite). D, anal somite and left caudal ramus.

Figure 5. Taurocletodes tumenae sp. nov. A, P1 ♀, anterior. B, P1 endopod ♀, posterior. C, P2 ♀, anterior. D, P2 ♂, anterior. E, left P5 ♀, anterior.

Figure 6. Taurocletodes tumenae sp. nov. A, P3 ♀, anterior. B, P3 ♂ (excluding praecoxa and coxa), anterior. C, P3 exopod ♂, outer lateral. D, P3 endopod ♂, medial. E, P4 ♀, anterior. F, P4 ♂, anterior. G, ♀ genital field.

Figure 9. Taurocletodes tumenae sp. nov. A, P1 endopod ♀, penicillate seta on enp-3 (tubular extension arrowed). B, antennule ♂, segments 5–7, anterior (modified elements arrowed). C, fifth and sixth legs ♂, ventral (functional gonopore arrowed).