Pseudomma kryotroglodytum, Wittmann & Chevaldonné, 2021
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publication ID |
https://dx.doi.org/10.3897/zookeys.1079.76412 |
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lsid:zoobank.org:pub:55F9DF83-DE92-4EC3-ACEC-05AA4466F147 |
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https://treatment.plazi.org/id/5B212BFB-7ADE-41CE-A671-CFC363B95A1C |
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taxon LSID |
lsid:zoobank.org:act:5B212BFB-7ADE-41CE-A671-CFC363B95A1C |
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scientific name |
Pseudomma kryotroglodytum |
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sp. nov. |
Pseudomma kryotroglodytum sp. nov.
Figures 2 View Figure 2 , 3 View Figure 3 , 4 View Figure 4 , 5 View Figure 5 , 6 View Figure 6 , 23A, B, D View Figure 23
Type series.
Holotype spent female (♀0-) BL 26.8 mm (on slides at NHMW 27296, GenBank nos. OK351330 and OK353694), East Antarctica, Adélie Land, near Dumont d’Urville Station, NE of Claude Bernard Island, 66°39.64'S, 140°01.55'E, ice cave, dive #612, depth 10 m, diver-operated suction bottle, 15 Jan 2016, leg. P. Chevaldonné & S. Hourdez. Paratype subadult female (♀S-) BL 21.5 mm (on slides at NHMW 27297, GenBank nos. OK351329 and OK353693), dive #611, 13 Jan 2016, remaining sampling data as for holotype.
Diagnosis.
Covers females only. Species of the genus Pseudomma G.O. Sars, 1870, with cornea-like lateral portions separated by sulci from main part of eyeplate (Figs 2B View Figure 2 , 4C View Figure 4 , 23A View Figure 23 ), no visual elements. Disto-median fissure penetrates one third of eyeplate. Distal margin of eyeplates with series of minute teeth along sublateral sector ( ‘shoulders’, Fig. 23A, D View Figure 23 ). Basal segment of antennular trunk without medio-ventral carina. Antennal scale (Fig. 4B View Figure 4 ) with setose apical lobe contributing about 1/4 scale length. Mandibular palp (Fig. 4E View Figure 4 ) 3-segmented, very large, about as long as antennal scale. Three pairs of oostegites (Fig. 5I View Figure 5 ) contributing to wall of brood pouch. Pleopods (Fig. 6H-L View Figure 6 ) reduced to setose rods with residual differentiation of endopod (pseudobranchial lobes). Telson (Figs 3A View Figure 3 , 6N View Figure 6 ) trapezoid, as long as ultimate pleonite. Its length twice maximum width at basis and four times width at apex. Lateral margins of telson without setae and spines, only minute scales present. Transversely truncate terminal margin with only two pairs of spines, both hispid due to minute scales (Fig. 3B View Figure 3 ) along more than proximal 2/3 spine length. Large latero-apical and same-sized submedio-apical spines flank median pair of closely set setae (Fig. 3C View Figure 3 ) with twice spine length. Margin with short, well-rounded indentation between each spine, median indentation largest. Disto-lateral edge without tooth, with spine only.
Description of the holotype.
All features of the diagnosis. Female with body length 26.8 mm. Cephalothorax measures 39% body length, pleon without telson 48%, telson 13% and carapace 32%. Large parts of the body, particularly carapace, pleon, telson, and uropods scaly-hispid; most appendages and eyeplates only to a minor degree. However, with 30 × episcopic microscopy, the entire body appears smooth (Fig. 3D-E View Figure 3 ) due to small size of scales. With 600 × transmitted phase contrast microscopy, large areas of the (artificially shed) dorsal cuticle of the animal resembles fish skin (Fig. 3F View Figure 3 ) due to dense scale cover. Ventral portions of pleomeres less densely covered, thoracic sternites smooth.
Antennula (Figs 2B View Figure 2 , 4A View Figure 4 ). Epi-antennular process triangular, projecting in median position beyond eyeplate like a small arrowhead (Fig. 2B View Figure 2 ). Antennular trunk with three sparsely setose segments, separated by transverse articulations. Basal segment 45%, median segment 16% and terminal segment 39% trunk length. Length of basal segment is only 2/3 width; mid-dorsally with deep antennular depression leading down to a striated pad at the bottom (Figs 4A View Figure 4 , 24A, B View Figure 24 ) as described below. Basal segment not produced at outer distal corner. Terminal segment with the usual dorsal lobe on distal margin. This lobe without spiniform extension, disto-laterally with four barbed setae, mid-terminally and disto-medially with thickened, rugged margin. Flagella large, width of outer flagellum measured near basis with 1.1-1.2 times width of inner flagellum. Trunk with scales over major portions of its surface, not so the flagella.
Antenna (Fig. 4B View Figure 4 ). Antennal scale large, 1.8 times length of antennular trunk and 1.8 antennal peduncle. Scale extends 0.4 times its length beyond antennular trunk and 0.7 beyond eyeplate (taking into account that antennulae insert more rostrally). Scale unsegmented, 2.9 times longer than wide. Scale dorsally and ventrally scaly-hispid all over. The smooth portion (not considering minute cuticle scales) of its outer margin ends in a strong tooth; setose apical lobe extends 26-27% scale length beyond this tooth. Antennal peduncle three-segmented. Basal segment contributes 21%, median segment 42% and terminal segment 36% peduncle length. Sympod angular on disto-lateral edge, not forming a tooth-like projection. Sympod with hispid lateral face.
Eyes (Figs 2B View Figure 2 , 3D View Figure 3 , 4C View Figure 4 , 23A, B, D View Figure 23 ). Eyeplate extending 0.9 times the length of terminal segment of antennular trunk along mid-line beyond anterior margin of carapace. Length of eyeplate, including its dorsally covered portion, 1.3 times the length of terminal segment. In dorsal view, superimposed dorsal and ventral sulci separate cornea-like lateral portions from main part of eyeplate (Figs 2B View Figure 2 , 4C View Figure 4 , 23A View Figure 23 ). Eyeplate containing tear-shaped cyst narrowing distally up to conjunction with eyeplate cleft (Fig. 23B View Figure 23 ). Sub-lateral portions of dorsal face with cover of minute scales (as in Fig. 3F View Figure 3 ; visualised with 400 × microscopy), series of 15 minute teeth (not all in focus in Fig. 23D View Figure 23 ), closely set along anterior margin of this portion. Brilliant red cornea-like portions of eyeplate feign functional eyes in living specimens (Fig. 2B View Figure 2 ). Eyeplates become transparent (Figs 4C View Figure 4 , 23A View Figure 23 ) after expansion on slide, embedding in Swan-medium and resultant bleaching; neither functional nor both vestigial ommatidia and neuronal structures visible.
Carapace (Figs 3D View Figure 3 , 4C View Figure 4 ) with broadly rounded anterior margin, disto-lateral edges well rounded. No typical rostral plate present, but a frontal bulge dorsally covered by the carapace; bulge best seen in lateral view (Fig. 3D View Figure 3 ). Antero-lateral edge of carapace with rounded protrusion (marked by arrows in Figs 3D View Figure 3 , 4C View Figure 4 ). By forcing the detached carapace in a plane (Fig. 4C View Figure 4 ), this protrusion becoming shifted caudally compared with its position in situ (Fig. 3D View Figure 3 ). Carapace with cervical sulcus and cardial sulcus distinct; posterior margin concave, terminal indentation widely triangular. Two submedian groups of 8-10 pores symmetrically arranged directly in front of cardial sulcus (Fig. 4D View Figure 4 shows only seven pores in the smaller paratype). Carapace leaving posterior 1.5 thoracomeres dorsally exposed.
Mouthparts (Figs 4E, F View Figure 4 , 5A-C View Figure 5 ). Labrum normal (Fig. 5A View Figure 5 ), rostrally forming a broad, rounded bulge; most caudal portions with strong lamellae and cover of scale-like fringes. Basal segment of mandibular palp (Fig. 4E View Figure 4 ) contributing 9-10%, median segment 55-56% and apical segment 35-37% to total palp length. Length of median segment 3.1-3.2 times maximum width; its mesial margin convex, lateral margin sigmoid. Length of apical segment 3.7-3.8 times maximum width. Palp not hispid, its basal segment without setae, remaining segments densely setose along mesial and lateral margins. Caudal face of median segment with dense field of fine hairs near basis. Masticatory part of mandibles strong, asymmetrical. Left mandible as normal in Mysidae . Pars incisiva of the new species with three large teeth and digitus mobilis with four strong teeth. Spine row with four spines ‘serrated’ by numerous stiff bristles; processus molaris with grinding lamellae not ending in teeth and with dense cover of stiff bristles. Right mandible as normal in the genus Pseudomma ; in the new species with four large teeth on pars incisiva; digitus mobilis with only one large apical tooth serrated by secondary teeth. Right spine row present as series of nine medium-sized smooth teeth plus a few small ones, rather than a smaller number of ‘serrated’ spines present on the left mandible as otherwise usual for both mandibles in Mysidae . Right processus molaris with strong masticatory lamellae, each with small, tooth-like, apical projection; processus with cover of stiff bristles less dense than that of left mandible.
Paired labia (Fig. 5B View Figure 5 ) with stiff setae, lacking spines or teeth. Distal segment of maxillula (Fig. 4F View Figure 4 ) with 11-12 weakly serrated, strong spines on terminally truncate margin; subterminally with 5-6 barbed setae. Holotype with 5-9 pores on the surface between setae bases and spines; potential additional pores may be covered by these setae (no pores identified in the paratype). Endite of maxillula with numerous normal setae; distally with three large, modified setae, armed with stiff bristles near apex¸ more proximally with a shorter seta bearing an apical brush of long bristles.
Maxilla (Fig. 5C View Figure 5 ) with well-developed exopod, two-segmented endopod (palp) and four setose endites. Exopod normal-sized, shortly extending beyond basal segment of endopod. Outer margin and apex of exopod with dense series of plumose setae distally increasing in size. Length of apical segment of endopod 1.5-1.6 times its maximum width and 1.2-1.3 times length of the basal segment. Basal segment with total of eight barbed setae, namely 3-4 on caudal and 4-5 on rostral face. Apical segment with setae all around, except for proximal third of lateral margin.
Foregut (Fig. 6A-E View Figure 6 ). Lateralia, infoldings and superomedianum of the cardiac chamber densely covered by smooth, slender setae and spines. Lateralia anteriorly with dense series of slender, apically coronate spines (Fig. 6B View Figure 6 ) of different length, more caudally with slender acute spines (Fig. 6C View Figure 6 ). The latter spines with minute teeth on and close to apex. Both coronate and acute spines hispid due to minute scales along distal 50-70% of shaft. Posterior part of lateralia with powerful complex of many blunt teeth arising from common base. Twelve teeth differentiated (Fig. 6E View Figure 6 ) with translucent microscopy, additional teeth not excluded. Dorsolateral infoldings with two smooth, bent spines (Fig. 6D View Figure 6 , subapically slightly serrate only in paratype). About 2/3 of comparatively large storage volume of foregut contained masticated, unidentifiable organic materials and mineral particles, also observed in paratype.
Thorax (Figs 2A, B View Figure 2 , 5D-I View Figure 5 ). At least tergites 6-8 covered by minute scales, no pores. Sternites 1-8 without pores, scales and also without ventrally projecting median processes (Fig. 5D View Figure 5 ). Sternite 1 with short anterior lobe projecting between left and right, first thoracic endopods. Basal plates of thoracic exopods (3-4) times longer than wide (Fig. 5D View Figure 5 ), not widening distally or only minimally so; lateral portions scaly-hispid, mesially smooth; disto-lateral edge unevenly rounded. Exopods 1, 8 with 15-segmented (Fig. 5D View Figure 5 ), remaining exopods with (17-20)-segmented, setose flagellum. Basis of endopod 1 with setose endite (below drawing plane in Fig. 5D View Figure 5 ), remaining segments without clear endite. Endopods 1, 2 with six segments (Fig. 5D, F View Figure 5 ), remaining endopods with eight segments counting from basis to dactylus (basis omitted in Fig. 5G View Figure 5 ). Endopods 3-8 long and slender; length and slenderness increase caudally; ischium shows the strongest relative increase (Fig. 2A View Figure 2 ). All endopods with hispid carpopropodus and dactylus, endopods 2-8 in addition with hispid merus, to a minor degree, if any, also ischium. Carpopropodus 3-8 three-segmented; more than half its length contributed by basal segment. Setae patterns might feign additional subdivision of carpopropodus (Fig. 5G View Figure 5 ). Suture between median and terminal segment transverse in carpopropodus 3, weakly (Fig. 5G View Figure 5 ), but not always distinctly oblique in carpopropodus 4, weakly and distinctly oblique in carpopropodites 5-8. Dactylus 3-8 small. Dactylus 1, 3-8 with short, smooth claw (Fig. 5E, H View Figure 5 ). No claw detected in dense jungle of setae on dactylus 2.
Marsupium (Fig. 5I View Figure 5 ) empty in this specimen. Basal to median portions of dorsal margin without setae in oostegite 1, without setae from basal to subapical portions in oostegites 2 and 3. A narrow ‘fur’ of densely set tiny hairs forming a ribbon along dorsal margin of oostegite 1 (Fig. 5I View Figure 5 ), no such hairs in oostegites 2 and 3. Scales on large portions of outer face in oostegites 2 and 3; no scales seen on oostegite 1. Ventral and anterior margins plus part of posterior margin with dense series of barbed setae, together with bilaterally opposite oostegite forming gate contributing to the ventral and caudal closure of marsupium (this configuration not impeding respiratory water flow through marsupium). Numbers of barbs per seta increase distally, albeit not reaching those of typical plumose seta. Oostegite 1 with barbed setae also on distal half of dorsal margin, suggesting pervious anterior closure of marsupium. Posterior parts of oostegites 1-3 on inner face with comparatively long setae microserrated on their distal half. Outer face of oostegites 2 and 3 with slender whip setae characterised by barbed shaft bearing longer thin flagellum. These setae implanted on distal portions of oostegites 2 and 3; additional whip setae along ventral margin only in oostegite 3. No whip setae in oostegite 1.
Pleon (Figs 3E, F View Figure 3 , 6F-J View Figure 6 ). Pleonites 1-5 are each 0.6 times length of pleonite 6 measured along dorsal mid-line. Pleopod size increases distally. Pleopods 4-5 reaching only up to 2/3 length of pleonites 5 or 6, respectively. Not considering setae, pleopod 1 smooth (Fig. 6H View Figure 6 ) all around, remaining pleopods completely smooth only on caudal face, though scaly-hispid at least near basis of rostral (outer) face. Relative coverage with scales increases in series of pleopods 2-5 (Fig. 6I-L View Figure 6 ). All six pleonites dorsally densely covered by minute scales. Only pleonite 1 showing pores, namely two symmetrical transverse linear series each with 17-18 discontinuously spaced pores, in submedian position on dorsal face; and one additional, non-linear cluster of 8-9 pores on each lateral face (Fig. 6F-G View Figure 6 shows fewer pores for the smaller paratype). Scutellum paracaudale sinusoid, well rounded.
Tail fan (Figs 3A-C, E View Figure 3 , 6M, N View Figure 6 ). Telson, endopod and exopod of uropods 1.0, 1.1-1.3 or 1.5-1.8 times length of sixth pleonite, respectively. Uropods (Figs 3E View Figure 3 , 6M View Figure 6 ) long, margins setose all around, dorsal and ventral faces scaly-hispid. Exopod with slightly convex, almost straight lateral margin and with more strongly convex mesial margin. Both margins diverge up to maximum width of the exopod at 1/3 length from basis and then converge up to the U-shaped, well-rounded terminus. Distal 4/5 of endopod with straight margins converging in V-shaped manner up to narrowly blunt apex. Endopod 0.7 times length of exopod, extending 1/5 of its length beyond telson, exopod 2/5 its length. Both statoliths unevenly discoid, mean diameter 0.22-0.23 mm, thickness 0.18 mm; core unevenly discoid as well, diameter 0.14 mm. Statolith formula 2 + 3 + (5-7) + 10 + (12-14) = 34. Statoliths composed of fluorite. Lateral margins and dorsal face of telson (Fig. 6N View Figure 6 ) completely covered by scales as in Fig. 3F View Figure 3 , whereas ventral face only on its distal third.
Colour (Fig. 2A, B View Figure 2 ). Live colour was documented only in the laboratory; no difference visible between the two type specimens. Body and appendages generally whitish transparent. Lateral portions of eyeplate, foregut and part of mouthparts brilliant red, hepatic caeca yellow-green. The anterior pair of caeca covers part of the foregut dorsally, leaving a red M-like sign on the foregut in dorsal view. Posterior part of ultimate pleomere and adjoining basal portions of tail fan tinged light-red.
Etymology.
The species name is an adjective with Latinised neutral ending formed by adjectivation of the amalgamated Ancient Greek adjective κρύος (cold) with the noun τρωγλοδύτης (cave dweller). The adjectivation has precedence in the name of the butterfly Macroglossum troglodytus Boisduval, l875, listed by Kemal et al. (2019) as M. troglodytum .
Type locality.
Marine ice cave NE of Claude Bernard Island, Adélie Land, East Antarctica, 66°39.64'S, 140°01.55'E, depth 10 m.
Subfamily Heteromysinae Norman, 1892
Tribe Mysidetini Holt & Tattersall, 1906
No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.
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