Ectinosomatidae, Sars, 1903

Kihara, Terue & Huys, Rony, 2009, A new genus of Ectinosomatidae (Copepoda, Harpacticoida) from sublittoral sediments in Ubatuba, São Paulo State, Brazil, including an updated key to genera and notes on Noodtiella Wells, 1965, ZooKeys 17 (17), pp. 57-88 : 80-83

Key to the Genera of Ectinosomatidae

The genus Tetanopsis Brady, 1910 (type species: T. typicus ) is included in the key below based on its allegedly 1-segmented antennary exopod, however, it should be recognized that its status is currently doubtful ( Huys et al. 1996; Wells 2007) as well as the grounds for subsequently allocating T. medius Perkins, 1956 , T. smithi Perkins, 1956 and Arenosetella mediterranea Chappuis, 1954b to this genus ( Perkins 1956; Lang 1965).

The antennary exopod of Ectinosomoides was claimed to be entirely absent ( Nicholls 1945) and this character was adopted by Wells (2007: 381) in his tabular keys. Huys et al. (1996: 158) scored the exopod as 3-segmented in their dichotomous key and this condition has been confirmed by re-examination of the single female of E. longipes Nicholls, 1945 found among the type material of Neoleptastacus spinicaudatus Nicholls, 1945 (cf. Sak et al. 2008: 435).

Nicholls (1935) established the genus Hastigerella for a new species Hastigerella palpilabra Nicholls, 1935 but McLachlan and Moore (1978: 198) relegated it to a junior synonym of Ectinosoma tenuissima Klie, 1929 and – based on their assertion that Nicholls (1935) had overlooked the anal claws – transferred this species to Arenosetella . They retained Hastigerella as a valid generic name and illegitimately designated Ectinosoma leptoderma Klie, 1929 as the new type species (ICZN Art. 61.1.3). Huys (2009) pointed out that adopting McLachlan and Moore’s (1978) synonymy of H. palpilabra would render Hastigerella a junior subjective synonym of Arenosetella and therefore an invalid name. He proposed a new name, Glabrotelson (type species: Hastigerella mehuinensis Mielke, 1986 ), for the orphaned taxonomic grouping equivalent to Hastigerella sensu McLachlan and Moore (1978) .

Seifried et al.’s (2007) course of action to upgrade the subgenus Bradya (Parabradya) to full generic rank appears premature since this leaves Bradya (now equivalent to its nominotypical subgenus) with only one questionable autapomorphy and hence a potentially paraphyletic status. Th e authors considered the maxillipedal endopod being fused to the basis at an angle as suffi cient evidence to warrant separate generic status for the nominotypical subgenus Bradya . However, as the authors admitted themselves the fusion is not complete in some as yet undescribed Bradya species. Both Bradya and Parabradya are retained here as valid genera but an in-depth study of all species accommodated in the former genus is required before the validity of this separation can be confirmed. Lang (1936) showed 5 setae on the exopodal lobe of the female P 5 in Parabradya confluens ( Lang, 1936) . Th is is a very unusual condition not found in any other extant member of the Ectinosomatidae (see also Seifried et al. 2007) and would require re-examination of the type material before it can be used for identification.

As has been pointed out by Karanovic and Pesce (2001), Vervoort (1962: 399) explicitly fixed Ectinosoma sarsii Boeck, 1873 as type species of the subgenus Ectinosoma (Halectinosoma) but Lang (1965: 11), who upgraded Halectinosoma to generic status, did not mention Vervoort’s (1962) designation. A comparison of the diagnoses of the two subgenera given in Lang (1944: 6) shows that Halectinosoma is distinguished from Ectinosoma on the basis of the setation of the exopod of leg 5. Th erefore, the generic name Halectinosoma is available from Vervoort (1962), who cited (p. 255) that page in Lang (1944) in this connection and designated a type species ( Huys 2008, 2009).

Wells and Rao (1987) placed their new species Halophytophilus aberrans with some diffidence in the genus Halophytophilus because it showed significant differences with its congeners in the non-prehensile P1 endopod and the armature of the P2–P4 endopods, in addition to discrepancies in the accessory ornamentation of the swimming legs and abdomen, and in the P5 and the caudal rami. The authors believed that there was a case for proposing a new subgenus for this species while Huys et al. (1996) surmised that it may belong to a separate genus. Bodin (1997) and Wells (2007) placed H. aberrans in the genus Klieosoma without giving any factual justification for this course of action. Gheerardyn et al. (2008) did not consider the species in their review of the genus Halophytophilus . It has now come to our attention that Wells and Rao’s (1987) setal formula of P4 contradicts their illustration. In their description the authors stated that P2–P4 exp-1 lacks an inner seta while their Fig. 28f clearly shows a well developed seta on this segment in leg 4. Huys et al. (1996) constructed their generic key on the assumption that this seta was absent in all swimming legs and hence H. aberrans may have keyed out to the wrong couplet. Without any illustrations of the maxilla (although Wells and Rao did state that the mouthparts were as in H. simplex Wells & Rao, 1987 ) and P2–P4 it is impossible to decide which genus H. aberrans belongs to and, consequently, it is here considered species incertae sedis in the Ectinosomatidae . A dichotomous key to the 21 valid genera in the Ectinosomatidae is given below.

1 Body cylindrical with cephalothorax rectangular in dorsal aspect; body approximately the same width throughout its length ...................................... 2

– Body fusiform with cephalothorax sub-triangular in dorsal aspect; greatest body width usually at posterior margin of cephalothorax; urosome gradually tapering towards the posterior end .............................................................. 8

– Body with dorsoventrally depressed prosome, clearly wider than urosome .... .......................................................... Peltobradya Médioni & Soyer, 1968

2 Antennary exopod 2-segmented; maxilla prehensile, with major articulation between elongate syncoxa and elongate allobasis ...... Noodtiella Wells, 1965

– Antennary exopod 1- or 3-segmented; maxilla not prehensile, with at most a slight angle between syncoxa and allobasis .................................................. 3

3 Endopods P2–P4 2-segmented ................... Ectinosomoides Nicholls, 1945

– Endopods P2–P4 3-segmented ................................................................... 4

4 Anal somite with dorsal armature of claws, lappets or spiniform processes around anal opening; P5 exopod with 3 marginal and 1 surface seta............. ........................................................................... Arenosetella Wilson, 1932

– Anal somite without such ornamentation ................................................... 5

5 Antennary exopod 1-segmented.............................. Tetanopsis Brady, 1910

– Antennary exopod 3-segmented.................................................................. 6

6 Female P5 with foliaceous setae on exopod and baseoendopod, exopod with 3 marginal and no surface setae; male P5 exopod with 4 normal marginal setae............................................................................ Oikopus Wells, 1967

– P5 with normal setae on exopod and baseoendopod in both sexes, exopod with 3 marginal and typically a surface seta [absent in Hastigerella noodti Soyer, 1974 = G. soyeri ( Bodin, 1976) ]................. Glabrotelson Huys, 2009

7 P1–P4 endopods 2-segmented ...................... Pseudectinosoma Kunz, 1935

– P1 endopod 2- or 3-segmented, P2–P4 endopods 3-segmented.................. 8

8 P1 endopod prehensile................................................................................ 9

– P1 endopod not prehensile ....................................................................... 12

9 P1 endopod 2-segmented ......................................................................... 10

– P1 endopod 3-segmented ................... Klieosoma Hicks & Schriever, 1985

10 P1–P2 exp-3 with 2 outer elements .......................................................... 11

– P1–P2 exp-3 with 3 outer elements ............... Halophytophilus Brian, 1919

11 Antennule with large spine on segment 2 (and often segments 1 and 3); antennary exopod rudimentary, with 1-3 small setae; P1 enp-2 with 4 elements (1-2 pinnate and claw-like) ................................. Bradyellopsis Brian, 1925

– Armature elements on antennulary segments 1-3 setiform; antennary exopod well developed and 3-segmented; P1 enp-2 with 6 elements (outer one bifid and claw-like) ................................................................ Chaulionyx gen. n.

12 Maxilla prehensile, with syncoxa and allobasis forming right angle; P5 exopod poorly developed, short, fused to baseoendopod in female and distinct in male, with 3 marginal and no surface setae; body very small (<300 µm) ...... ................................................................... Sigmatidium Giesbrecht, 1881

– These characters not combined ................................................................. 13

13 P5 exopod and baseoendopod fused, forming a single plate in both sexes ..... ................................................................................................................. 14

– P5 exopod and baseoendopod at least partly discrete ................................ 15

14 P1–P4 exp-3 with 5, 6, 6, 6 elements, respectively; male P6 unarmed; body of female small (<400 µm); continental groundwater................................... ..................................................... Rangabradya Karanovic & Pesce, 2001

– P1–P4 exp-3 with 6, 7, 8, 8 elements, respectively; male P6 with 2 setae; body of female large (≥ 1200 µm); marine, usually deepwater....................... .............................................................................. Parabradya Lang, 1944

15 Integument of somites with distinctive subrectangular pores; P5 exopod with 4 marginal setae .................................................... Ectinosoma Boeck, 1865

– Integument of somites without distinctive subrectangular pores; P5 exopod with 3 marginal setae and 1 seta on anterior surface.................................. 16

16 Mandible with rudimentary gnathobase, elongate basis and filiform rami, each terminating in 2-3 setae; antennary exopod without lateral spines......... ............................................................................ Ectinosomella Sars, 1910

– These characters not combined ................................................................. 17

17 Third segment of female antennule 3 times as long as wide; mandibular endopod with one strong seta laterally; P1–P4 exp-3 with 2 outer spines; planktonic (occasionally in sediment)..... Microsetella Brady & Robertson, 1873

– These characters not combined ................................................................. 18

18 Body comparatively robust with prosome-urosome separation usually distinct (exception: B. kurtschminkei Seifried & Martínez Arbizu, 2008 with dorsoventrally flattened habitus); antenna with 2 setae on proximal exopod segment and 1 seta on proximal endopod segment; mandibular exopod with at least 5 setae; maxilliped robust with short endopod usually fused at an angle with basis and bearing 4 conspicuous setae ......... Bradya Boeck, 1973

– Body comparatively slender with no sharp separation between prosome and urosome; antenna with less than 2 setae on proximal exopod segment (except Pseudobradya ambigua Sars, 1920 with 2) and no seta on proximal endopod segment; mandibular exopod generally with fewer than 5 setae; maxilliped usually slender and straight with discrete endopod bearing 1 small and 4 conspicuous setae...................................................................................... 19

19 Antennule with or without dark pigment spot within the proximal three segments; maxilla prehensile, allobasis usually truncate distally and carrying 3-segmented endopod (although endopod sometimes very small and segmentation diffi cult to discern; reduced to a a narrow 3-segmented cylinder in P. leptognatha Sars, 1920 ); maxilliped short and robust..................................... ............................................................................ Pseudobradya Sars, 1904

– Antennule without pigment spot; maxilla with at most a slight angle between syncoxa and allobasis, the latter generally attenuating distally, endopod 3-segmented but always small, its morphology not clearly discernible; maxilliped generally slender .......................................... Halectinosoma Vervoort, 1962

Figures

Figures 27-37. Chaulionyx paivacarvalhoi gen. et sp. n. Scanning electron micrographs (♀: 27-35; ♁: 36-37): 27 rostrum, dorsal 28 labrum, anterior 29 bifid outer spine on P1 enp-2 30 second abdominal somite (posterior margin), third abdominal somite, anal somite and caudal rami, dorsolateral 31 detail of serrate posterior margin of second abdominal somite 32 detail of posterior margin of third abdominal somite 33 posterior margin of anal somite 34 posterior margin of caudal ramus showing dorsal semicircular serrate extension 35 P5, anterior 36 prosomal ornamentation, dorsal 37 P1 endopod, anterior. Scale bars: 1 µm (34), 2.5 µm (33), 5 µm (28-29, 31-32, 35), 10 µm 27 (30, 37), 20 µm (36).