Kephyes hiulcus, Grossmann, Mary Matilda & Lindsay, Dhugal John, 2017

Grossmann, Mary Matilda & Lindsay, Dhugal John, 2017, A new species of clausophyid calycophoran siphonophore (Cnidaria: Hydrozoa), Kephyes hiulcus sp. nov., widely distributed throughout the world's oceans, Zootaxa 4250 (1), pp. 43-54 : 44-53

Kephyes hiulcus sp. nov.

Kephyes sp. A. Grossmann & Lindsay 2013, Grossmann et al., 2015 Kephyes ovata . Pugh 2006 ( Figs. 1 , 5A)

Kephyes ovata . Mapstone 2014 (Fig. 5D)

Diagnosis. Anterior and posterior nectophores conical, ridgeless, laterally compressed. Nectosac extending to 90% height of nectophores, with looped radial canals. Lateral canals arise from upper canal, either together or separately. Pedicular canal with long descending diverticulum in both nectophores. Somatocyst thin, extending to nectophore apex. Hydroecium open over entire height of both nectophores, and without median mesogloeal protuberance from the hydroecial wall; hydroecial flaps ending slightly before ostial level, large hydroecial wings in posterior nectophore.

Eudoxids cannot, at present, be differentiated from those of K. ovata .

Material examined. Holotype: Polygastric stage comprised of attached anterior and posterior nectophores, and anterior part of siphosomal stem. Collected at 1189 m in Monterey Canyon by the ROV ‘ Tiburon ’ (dive T0980- D 4, 10 May 2006, 36°36’11.909” N, 122°22’31.998” W) . The holotype was deposited at the Showa Memorial Institute, National Science Museum , Tokyo (NSMT-Co1579).

Additionally, twenty-one anterior nectophores and 25 posterior nectophores of Kephyes hiulcus sp. nov., ninety-seven anterior nectophores and 35 posterior nectophores of K. ovata , two complete Kephyes spp. free-living eudoxid stages, 302 bracts and 246 gonophores were analyzed, from Japanese waters and the Celebes and Mediterranean Seas (Table 1).

Description of Holotype. Nectosome: Anterior nectophore ( Figure 1 ): The type specimen was 12.6 mm in height and 3.6 mm wide in its preserved state. It was conical in shape, laterally flattened, without ridges; nectosac extending to 90% of nectophore height; no mouth plate; lateral radial canals arising from upper radial canal, with origins of right and left canals staggered, following a looped course, and inserting onto ostial ring canal in its lower lateral half; insertion point of pedicular canal at 40% nectophore height from the ostium; descending diverticulum from the pedicular canal remaining in contact with the hydroecium, extending at least to posterior end of hydroecial flaps; somatocyst remained in contact with hydroecium to 60% nectophore height before penetrating into the mesogloea, ending close to the apex of the nectophore; hydroecium open over the whole height of the nectophore, 20 to 45% of the nectophore width; hydroecial wings smooth and rounded, ending slightly anterior of the ostium, small projection of thickened mesogloea on external edge of hydroecial wings 1/3 nectophore height from the ostium.

Posterior nectophore 12.9 mm in height and 4 mm wide in its preserved state; conical in shape, laterally flattened, without ridges; nectosac extended to 90% of the nectophore in height; no mouthplate; lateral radial canals arising together from upper radial canal, following a looped course, joining ostial ring canal in its lower lateral half; insertion point of pedicular canal 60% nectophore height from the ostium; descending branch of the pedicular canal remaining in contact with the hydroecium, extending at least to posterior end of hydroecial flaps; somatocyst remaining in contact with hydroecium for half its length before penetrating into the mesogloea, ending close to the apex of the nectophore; hydroecium open over the whole height of the nectophore; hydroecial wings large, ending slightly anterior of the ostium, with medial flaps on internal surface.

Siphosome: Siphosomal cormidia composed of a bract and a tentacle-bearing gastrozooid ( Figure 2A ). No gonophores could be observed. The bracts could not be distinguished from those described by Pugh (2006) for Kephyes ovata , or from any of the material of both species we have examined.

Gastrozooids pale tangerine in colour when alive.

Cnidoband of tentacle tentilla long and slender ( Figure 3 ). Although discharged nematocysts were not observed, the size and shape of the capsules suggested they were long thin microbasic mastigophores, measuring up to 112 µm in length, and smaller, elongate homotrichous anisorhizas measuring up to 41 µm in length. The terminal filament was covered in small, spherical nematocysts.

Bracts measured up to 2.38 mm in length. Flattened apically, expanded laterally to grip the stem ( Figure 2 B); neck-shield extensive, with small indentations on the posterior lateral corners; central phyllocyst spindle-shaped, extending to the apex of the headpiece; 2 longitudinal bracteal canals, up to 4/5 the neck-shield in length, sometimes curving sharply inwards in their most distal part, the right (when the neck-shield is downwards), being longer than the left.

Gonophore not observed.

Etymology. The specific name hiulcus is Latin meaning split or open, and refers to the wide-open or gaping hydroecium of the anterior nectophore of this species in comparison with the more-closed one of K. ovata .

Distribution. Type locality: Monterey Canyon, Eastern Pacific Ocean (36°36’11.909” N, 122°22’31.998” W)

Kephyes hiulcus sp. nov. samples have been collected in Monterey Canyon, in Japanese waters ( Grossmann & Lindsay 2013, as ‘ Kephyes sp. A’), in the Celebes Sea (Grossmann et al., 2015, as ‘ Kephyes sp. A’), as well as in the Catalan Sea, north-western Mediterranean Sea (Table 1). The Kephyes hiulcus sp. nov. holotype was collected at 1189 m in Monterey Bay, but specimens from Japanese waters were found throughout mesopelagic depths. Nectophores were found to be roughly the same size, and were often collected concurrently with K. ovata . All of the MULTI-SPLASH net samples containing K. hiulcus sp. nov. also contained K. ovata , and 50% of the net samples from Suruga Bay contained both Kephyes species. There was no obvious segregation between the two species, or between polygastric and eudoxid stages, with depth, salinity or water temperature. The holotype was collected in waters with a temperature of 3.5˚C, salinity of 34.46 and a dissolved oxygen concentration of 0.56 mL.L -1, while the K. hiulcus sp. nov. specimens from the Catalan Sea (Mediterranean Sea) were collected in waters with temperatures above 13.0˚C, salinity 38.18–38.50 and dissolved oxygen concentrations between 4.14 and 5.87 ml.L -1.

Kephyes ovata and K. hiulcus sp. nov. are the only members of the Clausophyidae for which the polygastric stage has been reported from the Mediterranean Sea.

Remarks. First figured as a photograph (Fig. 5A: 1002) in Pugh’s (2006) reclassification of Clausophyes ovata (Keferstein & Ehlers, 1860) into the genus Kephyes , the present species K. hiulcus sp. nov. is similar in size, shape and general aspect to K. ovata . However, it can easily be differentiated by the extent of the hydroecium in the anterior nectophore of the polygastric stage. In K. ovata , this extends to 70% of the nectophore in height from the ostium ( Pugh 2006), whereas in K. hiulcus sp. nov., the hydroecium is open over the entire height of the anterior nectophore. Additionally, the hydroecial wings do not extend to ostial level in K. hiulcus sp. nov., as they do in K. ovata , but end slightly anterior of the ostium, both in the anterior and posterior nectophores. In the posterior nectophores of K. hiulcus sp. nov., the anterior part of the somatocyst lies close to the apex of the nectophore, as in the anterior nectophore, while in K. ovata , the somatocyst does not reach the apex of the nectophore in the posterior nectophore.

The origin of the lateral radial canals on the anterior nectophores of K. hiulcus sp. nov. showed a great deal of variability, arising either from the upper radial canal, or from the insertion point of the pedicular canal, right and left canals not always arising together. It is interesting to note that on all anterior K. ovata nectophores studied where the radial canals were visible, the lateral radial canals originated from the insertion point with the pedicular canal, as was the case in specimens from the north-eastern Pacific ( Mapstone, 2009). Pugh (2006), when describing the variability of the origin of the lateral radial canal in K. ovata , used, by way of an example of the canals arising from the upper radial canal, the animal shown in his figure 5A ( Pugh, 2006: 1002), which is, in fact, K. hiulcus sp. nov.. However, it is clear from Patriti’s (1969) specimens from the Mediterranean that in K. ovata the lateral radial canals may also arise separately, and from the upper radial canal.

In Kephyes hiulcus sp. nov., neither the stem nor the posterior nectophore are attached level with the base of the somatocyst of the anterior nectophore, but rather some way down the hydroecial cavity. This can be clearly seen in the photograph of the living sampled holotype ( Figure 1 A). Although no scar could be observed on the preserved material, it is supposed that the stem and posterior nectophore join at the start of the somatocyst of the latter, as in species of the genus Clausophyes , and that in K. hiulcus there is an extremely elongate ‘somatocyst along the hydroecium’ somatocyst portion ( Haddock et al. 2005) from the origin of the stem attachment point to the penetrating somatocyst of the anterior nectophore.

The free-living eudoxid stages of the two Kephyes species cannot, at present, be differentiated. The eudoxid bracts of Kephyes spp. examined in the present study measured between 2.98 and 7.22 mm in length. The longitudinal canals were usually reduced, while the hydroecial canals extended to 15-20% of bract height from the posterior edge. On many bracts, the hydroecial canals ran in a smooth and slight curve towards the centre of the neckshield ( Figure 2 D), resembling those drawn by Pugh for K. ovata (2006, Fig. 3A : p.1000). However, other bracts had hydroecial canals curving sharply inwards at their posterior ends, as observed on the small K. hiulcus sp. nov. siphosomal bracts ( Figure 2 B), or again had one hydroecial canal bending inward at its posterior end, while the second had a bifurcated tip ( Figure 2 C). The phyllocyst observed in free eudoxid stage bracts was more tapered in its anterior part than in the attached siphosomal bracts. It extended to or close to the apex of the head-piece ( Figure 2 ). A well-developed hydroecial flap was present on the right hydroecial wing of all eudoxid stage gonophores studied.

TABLE]. List of samples examineđ for the present stuđy. *: Kephyes hiulcus sp. nov. Holotype specimen; a.n.: anterior nectophore; b.: bract; g.: gonophore; e.: euđoxiđ; pol.: polygastric stage; p.n.: posterior nectophore.

Species Zooid Depth Date Latitude Longitude Location Time Temperature (°C) Salinity Dissolved (No.) range (m) Oxygen (mL/L)

Kephyes hiulcus sp. nov. pol.(1)* 1189 10-May-2006 36.603 -121.376 Monterey Canyon Day 3.52 34.46 0.6

p.n.(1) 0 0 750 21-Jun-2012 40.966 2.064 Catalan Sea Night 13.01023.0 7 38.18038.5 4.105 . 9 p. n.(1) 0 0 750 21-Jun-2012 40.966 2.064 Catalan Sea Night 13.01023.0 7 38.18038.5 4.105 . 9 p. n.(2) 90001000 19-Feb-2000 2.472 122.480 Celebes Sea Night 405 34.55034.6 1.801.9 a.n.(1) 7500800 15-Mar-2006 34.700 139.832 east of Oshima ( Japan) Day 3.7604.0 0 34.32034.34 1.201.5 a.n.(1) 8000850 15-Mar-2006 34.700 139.832 east of Oshima ( Japan) Day 3.5303.76 34.34034.37 1.201.4 a.n.(3) 8500900 22-Mar-2006 34.991 140.259 off Kamogawa ( Japan) Day 3.3403.42 34.37034.38 1.101.2 a.n.(1) 4500500 23-Mar-2006 35.008 139.333 Sagami Bay Day 6.3407.18 34.25034.26 1.802.1 a.n.(6) 5000550 23-Mar-2006 35.008 139.333 Sagami Bay Day 5.7206.35 34.25034.25 1.701 . 8 p. n.(3) 7500820 14-Mar-2006 35.008 139.333 Sagami Bay Night 3.6503.89 34.33034.36 1.301 . 4 p. n.(1) 0 9-Mar-1980 25.200 124.600 Suruga Bay Night n/a n/a n/a

a.n.(1) 397 27-Mar-1984 34.800 138.620 Suruga Bay Day 8.36 n /a n/a

p.n.(2) 480 27-Nov-1986 34.850 138.637 Suruga Bay Day 6.88 n /a n/a

p.n.(5) 494.1 9-Mar-1980 25.200 124.600 Suruga Bay Night n/a n/a n/a

p.n.(1) 790 13-Nov-1992 34.858 138.633 Suruga Bay Night 3.94 34.36 n /a

a.n.(1) 990 15-Mar-1985 40.487 142.658 Suruga Bay Day n/a n/a n/a

a.n.(7) 1049 28-Mar-1985 34.795 138.617 Suruga Bay Day 3.16 n /a n/a

a.n.(2) 1105 27-Nov-1986 34.850 138.637 Suruga Bay Day 3.93 n /a n/a

p.n.(2) 1105 27-Nov-1986 34.867 138.638 Suruga Bay Night 3.93 n /a n/a

a.n.(1) 4000450 8-Nov-1991 34.888 138.632 Suruga Bay Day 7.1606.73 34.257034.302 n/a

p.n.(4) n/a 1980 n/a n/a Suruga Bay n/a n/a n/a n/a

Kephyes ovata a.n.(1) 3500400 24-Mar-2006 34.700 139.832 east of Oshima ( Japan) Day 7.0808.25 34.23034.28 2.302.6 a.n.(3) 3500400 25-Mar-2006 34.700 139.832 east of Oshima ( Japan) Night 6.7008.18 34.22034.29 2.302.6 a.n.(1) 4000450 24-Mar-2006 34.700 139.832 east of Oshima ( Japan) Night 6.47307.226 34.22034.26 2.202.4 a.n.(3) 4500500 24-Mar-2006 34.700 139.832 east of Oshima ( Japan) Night 5.8206.48 34.20034.25 2.002.3 ……continued on the next page TABLE]. (Continueđ)

Species Zooid Depth Date Latitude Longitude Location Time Temperature (°C) Salinity Dissolved (No.) range (m) Oxygen (mL/L) a.n.(1) 9000950 15-Mar-2006 34.700 139.832 east of Oshima (Japan) Day 3.2703.38 34.39034.41 0.901.2 ……continued on the next page

TABLE]. (Continueđ)

Species Zooid Depth Date Latitude Longitude Location Time Temperature (°C) Salinity Dissolved (No.) range (m) Oxygen (mL/L) a.n.(3) 480 27-Nov-1986 34.850 138.637 Suruga Bay Day 6.88 n /a n/a Kephyes spp. g.(1) 90001000 19-Feb-2000 2.472 122.480 Celebes Sea Night 4.0005.0 0 34.55034.60 1.801.9 ……continued on the next page

TABLE]. (Continueđ)

Species Zooid Depth Date Latitude Longitude Location Time Temperature (°C) Salinity Dissolved (No.) range (m) Oxygen (mL/L) b.(5) 5000550 24-Mar-2006 34.700 139.832 east of Oshima (Japan) Night 5.6005.85 34.19034.22 1.802.2 ……continued on the next page

TABLE]. (Continueđ)

Species Zooid Depth Date Latitude Longitude Location Time Temperature (°C) Salinity Dissolved (No.) range (m) Oxygen (mL/L) g.(4) 7000750 25-Mar-2006 34.991 140.259 off Kamogawa (Japan) Night 3.4804.10 34.29034.36 1.201.5 ……continued on the next page

TABLE]. (Continueđ)

Species Zooid Depth Date Latitude Longitude Location Time Temperature (°C) Salinity Dissolved (No.) range (m) Oxygen (mL/L) g.(14) 6000650 24-Mar-2006 35.008 139.333 Sagami Bay Night 4.6004.96 34.27034.28 1.501.6

Figures

FIGURE 1. Photograph (A) and line drawing (B) of the living holotype of Kephyes hiulcus sp. nov. in lateral view. Scale bars = 2 mm. (photograph by Steven Haddock, MBARI)

FIGURE 2. A: Photograph of the siphosomal cormidia of the preserved holotype of Kephyes hiulcus sp. nov., B: siphosomal bract of the preserved holotype, C, D: Kephyes spp. free-eudoxid bracts from Japanese waters showing the structure of the hydroecial canals. B and C in upper view, D in right lateral view. Scale bars = 1 mm.

FIGURE 3. A: a detached tentillum from the holotype of Kephyes hiulcus sp. nov. B: close-up of the cnidoband nematocytes. cb: cnidoband, h. a.: homotrichous anisorhiza, m. m.: microbasic mastigophores, pe: pedicel, tl: terminal filament.