Kyphocalanidae Family - Marine Planktonic Copepods

Calanoida ( Order )	details
Clausocalanoidea ( Superfamily )	details

Abbreviations or symbols

Kyphocalanidae Markhaseva & Schulz, 2009 ( Clausocalanoidea )

Ref.:

Markhaseva & Schulz, 2009 (p.22); Markhaseva & al., 2014 (p.63, 67, 79, Table 1, 2, 3, 4, Rem, Def..); Laakmann & al., 2019 (p.330, Table 1, fig. 1, 2, 3, Table A, phylogenetic relationships)

Rem.:

Type genus: Kyphocalanus Markhaseva & Schulz, 2009.
For Markhaseva & Schulz (2009, p.22) the new family shares sensory setae on Mx2 and Mxp with a group of clausocalanoidean Bradfordian families including Diaixidae, Parkiidae, Phaennidae, Rostrocalanidae, Scolecitrichidae and Tharybidae. However, Kyphocalanidae is unique among all Bradfordians in possessing various apomorphies.
For the authors (2009, p.37) this family is a derived benthopelagic ‘Bradfordian’ family with a large number of apomorphies shown by the setation of A2, Md, Mx1, Mx2 and Mxp syncoxa. The family does not share the presumed ancestral states of many benthopelagic ‘Bradfordians, viz. the 1st and 2 nd proximal exopodal segment of A2 are equipped with 1 and 3 setae respectively, praecoxal endites of Mxp showing a 1, 2, 3 setation pattern, and a maximum number of 9 setae on Mx1 endopod. However, Kyphocalanidae shares with Rostrocalanidae the absence of brush-like sensory setae on Mx1 endopod (at least 2 and usually 5 to 8 brush-like sensory setae are present in remaining ‘Bradfordians’ families Diaixidae, Parkiidae, Phaennidae ; Scolecittichidae and Tharybidae). However, Kyphocalanidae does not share synapomorphies of Rostrocalanidae (i.e., a 4-segmented Md exopod with 4 setae, the presence of 6 worm-like sensory setae on Mx2 endopod), and thus appears not to be closely related to that family. Apparently, Kyphocalanus is an early offshoot of ‘Bradfordian’ ancestors, i.e. a lineage that entirely lacked the development of comparably advanced brush-like setae, while only elementary worm-like sensory setae on Mx1 and Mxp have evolved. The comparatively increase in size of worm-like sensory setae in Kyphocalanus suggests that the evolutionary trend of the new genus was apparently connected with far-field detection of food particles and resulted in their strong morphological specialization.

For Markhaseva, Laakmann & Renz (2014, p.79) the diagnosis is based on the following combination of vharacters: the apomorphies for the family within the ''Bradfordians'' are :1 - Praecoxal arthrite of Mx1 with 3 setae and a distal basal endite with 1 seta; 2 - Mx2 endopod with 8 very long and thick worm-like sensory setae, longer than all remaining sclerotised setae of Mx2; 3 - Praecoxal lobes of Mxp with a setal formula as 1, 2, 0.

General characters :

1 - In males, proximal part of right A1 with only ancestral segments X-XI fused (see fig.5).

2 - A2 coxa with 1 seta; basis and endopodal segment 1 without setae, endopodal segment 2 with fewer than 13 setae; proximal segment of endopod without seta, setal formula of endopod : 0, 0-0-1, 1, 1, 1, 1, 1, 3 (see table 1).

3 - Md endopodal segment 2 with 9 setae; exopod 5-segmented with 5 setae; gnathobase without hump (crest) (see Table 2).

4 - Mx1 setal formula: 3, 2, 0, 1, 5, 7, 9 (see table 3).

5 - Mx2 endites setal formula: 2, 2, 2, 2, 1 (see Table 4).

6 - Mxp praecoxa setae as: 1w + 2w + 0; basis with 3 proximal and 2 distal setae (see Table 5).

7 - Male P5 biramous, of simple structure; right and left coxa and basis of neatly same length; exopods 3-segmented (see Fig. 7).

The authors note that Kyphocalanus shares an A1 basis witout setae with some species of Brodskius (versus usually 1-2 setae in other ''Bradfordian ''), Mx1 basal proximal endite with 2 setae with Diaiscolecithrix and some species of Bradfordiella (versus 3 in other ''Bradfordians''), also enditic lobe of endopod bearing 1 seta Kyphocalanus shares with Bradfordiella (versus usually 4 setae in other ((Bradfordians''). (see Table 1, 3-5).

Issued from : E.L. Markhaseva, S. Laakmann & J. Renz in Mar. Biodiv., 2014, 44 [p.70, Fig.5].
Schematic view of right A1 in males of ''Bradfordian'' families. Kyphocalanidae.
Roman numerals: ancestral segments; black arrows: fused ancestral segments.

Issued from : E.L. Markhaseva, S. Laakmann & J. Renz in Mar. Biodiv., 2014, 44 [p.73, Table 1].
A2 armament (number of seta) in different ''Bradfordian'' genera (females). Kyphocalanidae.
c: coxa; b: basis; End1: endopod segment 1; End2: endopod segment 2; Exp: exopod.

Issued from : E.L. Markhaseva, S. Laakmann & J. Renz in Mar. Biodiv., 2014, 44 [p.74, Table 2].
Md armament (number of seta) in different ''Bradfordian'' genera (females). Kyphocalanidae.
b: basis; End1: endopod segment 1; End2: endopod segment 2; Exp: exopod; gn: gnathobase.

Issued from : E.L. Markhaseva, S. Laakmann & J. Renz in Mar. Biodiv., 2014, 44 [p.76, Table 3].
Mx1 armament (number of seta) in different ''Bradfordian'' genera (females). Kyphocalanidae.
pa: praecoxal arthrite (setal formula of praecoxal arthrite: terminal+posterior+anterior setae); ce: coxal endite; bp: proximal basal endite; bd: distal basal endite; End: endopod; Exp: exopod; Epi: epipodite.

Issued from : E.L. Markhaseva, S. Laakmann & J. Renz in Mar. Biodiv., 2014, 44 [p.78, Table 4].
Mx2 armament (number of seta) in different ''Bradfordian'' genara (females). Kyphocalanidae.
at: attenuation; pe: praecoxal endite; ce: coxal endite; bp: proximal basal endite; bd: distal basal endite; el: enditic-like lobe of proximal endopodal segment; End: endopod; w: worm-like seta; br: brush-like seta; sc: sclerotised seta.

Issued from : E.L. Markhaseva, S. Laakmann & J. Renz in Mar. Biodiv., 2014, 44 [p.80, Table 5].
Mxp setation (number of seta) in different ''Bradfordian'' genera (females). Kyphocalanidae.
at: attenuation; pes: praecoxal endites of syncoxa (from proximal to distal); ces: coxal endite of syncoxa; bp: basis proximal; bd: basis distal; End: endopod.
For more detailed morphology of the seta on the praecoxal endites of the maxilliped syncoxa see Markhaseva & Ferrari (2005) and Markhaseva & al. (2008).

Issued from :E.L. Markhaseva, S. Laakmann & J. Renz in Mar. Biodiv., 2014, 44 [p.72, Fig.7 i].
P5 from Kyphocalanus sp.
R: right leg; Exp: exopod; end: endopod.
Markhaseva (pers. obs.)

Issued from : S. Laakmann, E.L. Markhaseva & J. Renz in Mol. Phylog. Evol., 2019, 130. [p.331, Table 1].
compilation of information on relationships among ''Bradfodian'' genera from Markhaseva & Ferrari 2005) and Markhaseva & al. (2014).
Abbreviations: A2, antenna; Md, mandible; Mx1, maxillule; Mx2, maxilla; Mxp, maxilliped ; P5, leg 5. w, worm-like sensory seta; b, brush-like sensory seta; s, sclerotized seta.

(1) Kyphocalanus Markhaseva & Schulz, 2009

Species, varieties and details

Ref.:

Markhaseva & Schulz, 2009 (p.23); Markhaseva & al., 2013 (p.6, Table 1, 2, 3, 4, Rem.); Renz & Markhaseva, 2015 (p.96, Table 4, fig.3, biogeography); Laakmann & al., 2019 (p.330, Table 1)

Rem.:

Type species: Kyphocalanus atlanticus Markhaseva & Schulz, 2009. 1 sp + 4 without denomitation.
For Markhaseva & Schulz (2009, p.23-24) synapomorphies (commun possession of derived homologous characters ) for the genus Kyphocalanus are the presence of a knife handle-like basal part of the prosximal seta on the mandibular basis and the maxillule distal basal endite and endopod separate and the distal basal endite bearing 1 seta only (vs. 2-6 setae in other ‘Bradfordians’).
In addition to the characters of the family, the new genus differs from the majority of other ‘Bradfordian’ families/genera by the following derived characters :
1- A2 basis without setae, shared with tharybid genus Brodskius Markhaseva & Ferrari (2005), contrasting the presence of 1-2 setae in other ‘Bradfordians’.
2- A2 endopod segment 1 without setae, shared with Pseudophaenna Sars (1902) (genus of unclear familial position) and some species of the tharybid genus Undinella Sars (1900), and contrary to 1-2 setae in other ‘Bradfordians’.
3- A2 endopod segment 2 with fewer than 10 setae, shared with Pseudophaenna, but this segment with 11-15 setae in other ‘Bradfordians’.
4- Maximmule proximal basal endite without setae, shared with Bradfordiella Andronov (2007) (genus of unclear familial position), in contrast to the presence of 2-5 setae in other ‘Bradfordians’.
5- Maxilla proximal praecoxal endite with 2 setae, shared with Rostrocalanus and some species of Bradfordiella, but with 3-5 setae in other ‘Bradfordians’.
6- Maxilla distal praecoxal endite and proximal coxal endite with 2 setae each, shared with some species of Bradfordiella, and contrary to 3 setae in other ‘Bradfordians’.
7- Maxilla distal coxal endite with 2 setae, shared with Phaenna Claus (1863) (Phaennidae), but with 3 setae in other ‘Bradfordians’.
8- Maxilla proximal basal endite with 1 setal element, shared with Bradfordiella, but with 3-4 setal elements in other ‘Bradfordians’.
9- 1 seta on Maxilliped coxal endite, shared with some species of Undinella and Bradfordiella, in contrast to presence of 2 or 3 setae in other ‘Bradfordian genera’.
The similar derived armament of some oral limbs of Kyphocalanus and Bradfordiella is assumed to have arisen in a parallel development and independently, and thus both genera are not considered to be closely related. This is corroborated by apomorphies not shared by Bradfordiella : 1- praecoxal arthrite of Mx1 with 3 setae (vs. 9 in Bradfordiella ; 2- distal coxal endite of Mx2 with 2 setae (vs. 3 setae inBradfordiella ; 3- Mx2 distal basal endite plus endopod with 8 very long and thick, worm-like sensory setae, longer than all sclerotized setae of Mx2 (vs. only 6 short sensory setae of unclear morphology in Bradfordiella.
In addition, Kyphocalanus does not share apomorphies of Bradfordiella : 1- A1 of only 18 segments (vs. 24 in Kyphocalanus) ; 2- Mandibular basis lacking setae (vs. 2 setae in Kyphocalanus) ; 3- Mx1 with coxal and basal endites reduced (vs. these enditese well developed in Kyphocalanus) ; 4- Mxp praecoxal endites of syncoxa lacking setae (with 1, 2, 0 setae in Kyphocalanus).

Diagnosis from Markhaseva & Schulz (2009, p.23) :
Female :
- Cephalon in lateral view bent anteriorly.
- Rostrum as two short, prong-like points.
- Cephalosome and pediger somite 1, pedigers 4 and 5 separate.
- Urosome very short, of 4 somites, genital double-somite being the largest.
- A1 shorter than prosome.
- A2 : basis, endopodal segment 1 and exopodal segment 1 without setae ; endopodal segment 2 with 3 or 4 setae on inner lobe ; exopodal segment 2 with 1 short seta.
- Md gnathobase long and slender, with narrow cutting edge ; basis with 2 setae, proximal seta with conspicuous thickening at 1/3 length ; endopodal segment 1 without setae, segment 2 with 9 setae ; exopod 5-segmented with 1, 1, 1, 1, and 1 setae.
- Praecoxal endite of Mx1 with 3 slender setae ; proximal basal endite without setae ; distal basal endite with 1 seta and separate from endopod bearing 5 setae.
- Mx2 praecoxal and coxal endites usually with 2 slender setae each ; basal endite with 1 strong spine ; endopod with 8 long and thick worm-like sensory setae.
- Praecoxal lobes of Mxp syncoxa with 1 thin, slender and comparably short worm-like sensory seta on proximal lobe and 2 thick and long worm-like setae on medial lobe ; distal lobe without seta, setal formula 1, 2, 0 ; coxal endite with 1 slender seta.
- P4 coxa, basis, endopod, and exopod segment 1 with posterior surface spinulation or not.
-P5 3-segmented, exopod with 2 unequal spines (1 shorter, terminal and 1 longer, inner and subterminal spine).
Male unknown

Remarks on dimensions and sex ratio:

The mean female size is 2.10 mm (n = 4; SD = 0.1980), and only for one male 2.25 mm.