Plumularioid hydroids (Cnidaria: Hydrozoa) from off New Caledonia collected during KANACONO and KANADEEP expeditions of the French Tropical Deep-Sea Benthos Program Author Galea, Horia R. DE5AC672-0243-46F2-A910-AFF4E91A4C5D Hydrozoan Research Laboratory, 405 Chemin Les Gatiers, 83170 Tourves, France. horia.galea@gmail.com Author Maggioni, Davide 2A321960-E973-4742-B908-4394C0B9AF43 Università degli Studi di Milano-Bicocca, Dipartimento di Scienze dell’Ambiente e della Terra, Piazza della Scienza 1, 20126 Milano, Italy. & Università degli Studi di Milano-Bicocca, Marine and High Education (MaRHE) Center, 12030 Faafu Magoodhoo, Republic of the Maldives. davide.maggioni@unimib.it text European Journal of Taxonomy 2020 2020-08-26 708 1 58 journal article 10.5852/ejt.2020.708 0c523d70-0815-45f8-a69d-1698f78a0998 2118-9773 4011061 DDF28821-1A4A-4457-BB53-1696F3BFB7B2 Monostaechas fisheri Nutting, 1905 Figs 16A , 17 A–I, 18; Table 8 Monosteachas fisheri Nutting, 1905: 952 , pl. 5 fig. 3, pl. 12 fig. 8. Monostaechas fisheri Bedot 1921a: 6 . — Stechow 1925: 252 , 253. — Vervoort 1968: 64 . — Migotto 1996: 50–51 . — Schuchert 1997: 127 , fig. 46. Monostaechas quadridens Ansín Agís et al . 2009: 53 , fig. 9. —? Park 2010 ( pro parte ): 134, fig. 75a. — Watson 2011: 18 , fig. 9 [non Monostaechas quadridens (McCrady, 1859) ]. Monostaechas sp. – Ansín Agís et al . 2009: 54 , fig. 10. non Monostaechas fisheri Bedot 1921b: 9 . — Vannucci 1949: 252 , pl. 3 figs 51–54; 1950: 90, pl. 1 fig. 6; 1951: 106, 108, 112, 114. — Von Schenck 1965: 909 , figs 3d, 9 [all = Monostaechas quadridens (McCrady, 1859) ]. non Monostaechas fisheri var. simplex Billard, 1913: 16 , fig. 7, pl. 1 fig. 10 [= Monostaechas quadridens (McCrady, 1859) ]. non Monostaechas fisheri var. simplex Van Praët 1979: 914 , fig. 7, pl. 1 fig. 10 [= Monostaechas quadridens (McCrady, 1859) ]. Material examined PACIFIC OCEAN1 small colony with stems up to 1.5 cm high, some bearing simultaneously ♂ and gonothecae; off New Caledonia , stn DW4768; 23°25′ S , 168°01′ E ; 180–210 m ; 27 Aug. 2016 ; KANACONO leg.; MNHN-IK-2015-606 5 stems up to 2 cm high, some with gonothecae; off New Caledonia , stn CP4688; 22°29′ S , 167°31′ E , 278–353 m ; 14 Aug. 2016 ; KANACONO leg.; MNHN-IK-2015-607 . Additional material PACIFIC OCEANvariety with shallow hydrothecae and long lateral nematothecae: 1 fertile colony, with stems up to 3 cm high; off New Caledonia , stn DW4725; 22°41′ S , 167°05′ E ; 240–256 m ; 20 Aug. 2016 ; KANACONO leg.; MNHN-IK-2015-605 . Comparative material CARIBBEAN SEA1 profuse , fertile colony of Monostaechas quadridens McCrady, 1859 , on Sargassum sp.; France , Martinique , Anses d’Arlet; 14°29′ N , 61°05′ W ; 6–10 m ; 29 Jan. 2012 ; HRG-0853 . Fig. 16. A . Monostaechas fisheri Nutting, 1905 , two colonies from sample MNHN-IK-2015-605. — B . Thamnopteros uniserius Galea gen. et sp. nov. , holotype colony, MNHN-IK-2015-611. Scale bars: 1 cm. Table 8. Measurements of Monostaechas fisheri Nutting, 1905 , in µm.
Nominal species Variety
Present study, MNHN- IK-2015-606 and -607 ( * ) Ansín Agís et al. (2009) , MUSORSTOM 3, stn CP131 Watson (2011) , as M. quadridens Present study, MNHN- IK-2015-605 Ansín Agís et al. (2009) , SMIB 4, stn DW55
Stem
- internode length 1080–1375 1070–1750 1800–2500 775–1215 650–830
- diameter at node 120–210 100–130 136–224 125–195 120–190
- nematothecae, length ca 115 140–160
- nematothecae, diameter at rim ca 45
- cladial apophysis, length 280–320
- apophysis for secondary stem, length ca 125 88–120
Cladia
- ahydrothecate internode, length 250–500 370–550 240–360 215–315 270–350
- nematotheca, length 80–95 60–80 80–90
- nematotheca, diameter at rim 45–50 30–40 30–35
- hydrothecate internode, length 350–485 460–500 264–336 285–370 380–490
- diameter at node 80–120 60–100 80–96 50–100
Hydrotheca
- abaxial wall, length 240–350 240–270 273–320 155–180 160–220
- free adaxial wall, length 185–225 150–160 128–160 115–125 110–140
- adnate adaxial wall, length 235–250 165–185
- diameter at rim 275–300 220–300 256–280 205–225 210–230
- mesial nematotheca, length 70–90 60–70 88–100 ca 80
- mesial nematotheca, diameter at rim 60–70 ca 50 40–50
- lateral nematotheca, length 125–150 70–90 100–120 135–160 120–160
- lateral nematotheca, diameter at rim 60–80 45–60 45–55 45–50
- lateral nematotheca, apophysis length 120–140 95–110
- axillar nematotheca, length 70–80 58–80
- axillar nematotheca, diameter at rim 40–45
Female gonotheca
- length w/o pedicel 1170–1250 490–620 900–1160 ca 945
- maximum width 505–650 300–400 520–600 ca 625
- diameter at aperture 330–390 ca 385
- nematotheca, length 125–140
- nematotheca, diameter at rim 70–75
Male gonotheca
- length w/o pedicel 435–580 (*) 450–470 360–400 ca 400
- maximum width 215–255 (*) 200–260 216–224 ca 175
- diameter at aperture 45–65 (*)
- nematotheca, length 135–145 (*)
- nematotheca, diameter at rim ca 65 (*)
Fig. 17 (opposite page). A–B . Monostaechas fisheri Nutting, 1905 ,stem internode with proximal portion of cladium bearing a female gonotheca, from sample MNHN-IK-2015-607 (A); male gonotheca from sample MNHN-IK-2015-606 (B). — C–I . Monostaechas fisheri Nutting, 1905 , morphotype with shallower hydrothecae and longer lateral nematothecae: stem internode with proximal portion of cladium (C); lateral and axillar nematothecae from one side of a hydrotheca, seen laterally (D); axillar nematotheca occurring either singly (E) or in pairs (F), and detail of a theca seen from its adaxial side (G); male (H) and female (I) gonothecae; all from sample MNHN-IK-2015-605. — J . Monostaechas quadridens (McCrady, 1859) , stem internode with proximal portion of cladium bearing a female gonotheca, from sample HRG-0853, for comparison. Scale bars: A–C, H–J = 300 µm ; D–G = 100 µm . Description Colonies upright, up to 2 cm high, coplanar, rigid, with thick, brown perisarc, arising from creeping, branching, slightly flattened hydrorhiza. Stem monosiphonic; proximal part straight, irregularly divided into few internodes of varied length by means of transverse nodes; distalmost nodes with two parallel, closely-set rows of frontal nematothecae; remainder of stem divided into regular internodes by transverse nodes; each internode moderately long, straight, bearing one or two lateral apophyses and 4–6 frontal nematothecae in two closely-set rows; apophyses subterminal on internodes; when two of these are present on same internode, either opposite or subopposite; two types of apophyses: first type very short, ending in straight node and bearing secondary stem, and second type comparatively longer, ending in oblique node and bearing cladium; first regular thecate stem internode with either pair of dissimilar apophyses, one bearing secondary stem, the other a cladium, or with pair of apophyses supporting two secondary stem; in the latter case, following internode may bear two dissimilar apophyses; remainder of stem internodes with single apophyses supporting cladia only, distal part of stem assuming scorpioid shape, typical of genus. Secondary stems, like main stem, divided into regular internodes, each bearing nematothecae and upwardly-directed apophysis supporting cladium; consequently, all their cladia point upwards with respect to colony, and their hydrothecae all facing towards main stem. All cladia borne directly on main stem have their hydrothecae facing downwards in proximal part of colony and, as stem curves away in scorpioid manner, hydrothecal apertures of more distal cladia increasingly facing outwards or even upwards, depending of length of distal part of stem and number of cladia it bears. Cladia up to 8 mm long, heteromerously divided into hydrothecate and ahydrothecate internodes; up to 10 hydrothecate internodes per cladium, relatively short, each with proximal node oblique and distal node transverse, bearing hydrotheca in middle and its complement of nematothecae: one mesial, a pair of laterals, as well as axillar one on one side of hydrotheca; hydrotheca deep, tubular, half adnate, free adaxial wall and abaxial wall nearly straight, aperture circular, rim smooth; all nematothecae movable and bithalamic; laterals conical, borne on conspicuous apophyses, whole set reaching hydrothecal rim; upper chamber of lateral nematothecae lowered on adaxial side, and there with sinusoid margin. Cladial ahydrothecate internodes of varied length, with proximal node straight and distal node oblique, each bearing frontal nematotheca proximally. Stems either mono- or dioecious; gonothecae sexually dimorphic, borne exclusively on cladia by means of 2-segmented pedicel, given off laterally between base of hydrotheca and its mesial nematotheca; female gonothecae large, piriform, slightly flattened laterally, distally truncate and there with broad, thickened, ovoid aperture, proximally with 2–3 nematothecae; male gonothecae, comparatively smaller, ovoid, circular in transverse section, distally with small, rounded aperture, proximally with a nematotheca. Remarks The illustrations and measurements provided by Ansín Agís et al . (2009) leave little doubt that their material is conspecific with that dealt with herein. Although they identified it as M. quadridens (McCrady, 1859) , it could be demonstrated that they are specifically distinct. Indeed, Caribbean specimens ( Galea 2010 ), corresponding strictly to earlier descriptions of McCrady’s species, are more delicate in appearance and build exclusively scorpioid sympodia, while the present material is composed of comparatively stronger colonies with distinct, upright, straight main stems ( Fig. 17J ). Monostaechas fisheri is still a poorly-known, seldomly-recorded species. Speculations on its affinities with M. quadridens often provided inconclusive or cautious opinions (e.g., Stechow 1925 ; Vervoort 1968 ; Migotto 1996 ; Schuchert 1997 ), although some authors pleaded for a definitive inclusion in its synonymy (e.g., Leloup 1937 ; Watson 2011 ). Schuchert (1997) reexamined the type of M. fisheri and provided a comprehensive description and illustrations of it. It is mainly characterized by the presence of a definite, straight main stem, a peculiar mode of branching, with secondary stems arising singly or forming opposite pairs with a cladium (see also Nutting 1905 : pl. 5 fig. 3). No such branching pattern is known to occur in M. quadridens , although the existence of dichotomously-branched colonies (e.g., Allman 1877 : pl. 22 figs 1–5, as M. dichotoma ; Nutting 1900 : pl. 13 fig. 1; Vervoort 1968 ; Hirohito 1974 : fig. 16d; Calder 1983 ; Hirohito 1995 : fig. 84b) is not uncommon, while the occurrence of aberrant secondary stems ( Hirohito 1995 : fig. 84a) is a rare, peculiar condition. Unlike the present material from New Caledonia , the cladial ahydrothecate internodes of the type material of M. fisheri possess two nematothecae instead of only one, although no other differences could be noted between them. It is thus assumed that the present material is, with little doubt, conspecific with M. fisheri . Supporting this hypothesis, Watson (2011 , as M. quadridens ) noted the presence of 1–2 nematothecae in her specimens, with distinct stems that could probably be assignable as well to Nutting’s (1905) hydroid. Their color in life was “dark purplish grey”, thus different from the paleyellow colonies of M. quadridens from the Caribbean collected by Galea (2010) . Although Watson argued that her Australian material was indistinguishable from a colony of M. quadridens from Sapelo Island, GA, USA , no information, notably on the condition of the stem, was provided to support her statement. Only male gonothecae, bearing a single basal nematotheca, have been documented in M. fisheri ( Schuchert 1997 ) . The present material also possesses female gonothecae, of a much larger size compared to those of M. quadridens , and bearing 2–3 basal nematothecae, further supporting the specific separation between these species. Similar gonothecae were reported upon by Watson (2011 : fig. 9e). Specimens in material MNHN-IK-2015-605 show a more complex branching pattern of the main stem, with an increasing number of ramifications per site, and the formation of up to third order stems. Some examples of branching are illustrated in Fig. 18 . This appears to be a variety of the nominal species, distinguished by its proportionally smaller and shallower hydrothecae and longest (trumpet-shaped) lateral nematothecae, the other morphological characters, including the shape and size of gonothecae of both sexes, being similar to those of the nominal species. Fig. 18. Monostaechas fisheri Nutting, 1905 , morphotype with shallower hydrothecae and longer lateral nematothecae: patterns of branching. Slender lines represent cladia, thicker lines show primary, secondary or tertiary stems; dots correspond to the hydrothecae. A series of records attributed to M. fisheri are, most probably, based on misidentifications. Indeed, the Cape Verde material studied by Bedot (1921b) is said to exhibit all characters of M. fisheri var. simplex Billard, 1913 , which is now recognized as the simplest mode of colony growth met with in McCrady’s hydroid (e.g., Schuchert 1997 ). Additionally, Vannucci’s (1949 , 1950 ) material reportedly comprised both simple and ramified stems, although their mode of branching was not described in detail. On the account of their geographical occurrence and the size of their female gonothecae with respect to the hydrothecae ( Vannucci 1950 : pl. 1 fig. 6), it is believed that she actually had specimens of M. quadridens . Migotto (1996) agrees that “Vannucci’s description (1949) of M. fisheri […] clearly conforms with the current conception of M. quadridens ”. The colony illustrated by Park (2010 : fig. 75a, as M. quadridens ) shows a peculiar branching pattern, approaching the condition met with in the present species, and both could be conspecific. However, her description fits the classical concept of M. quadridens , as well as the size of the illustrated gonothecae ( Park 2010 : fig. 75b, d) do, but, since many colonies were available, it is conceivable that some belonged to one species, while some others to the second one. Distribution Hawai’i ( Nutting 1905 ),? Korea ( Park 2010 ), Australia ( Watson 2011 ), New Caledonia ( Ansín Agís et al . 2009 ; present study), Chesterfield Islands and Philippines ( Ansín Agís et al . 2009 ).