Teleotanais madara, Tanabe & Kakui, 2019

Tanabe, Yuki & Kakui, Keiichi, 2019, First Report of Teleotanaidae (Crustacea: Tanaidacea) from the Northwestern Pacific, with the Description of a New Species, Species Diversity 24, pp. 181-187 : 182-186

Family Teleotanaidae Bamber, 2008

[New Japanese name: Madara-tanaisu-ka] Genus Teleotanais Lang, 1956 [New Japanese name: Madara-tanaisu-zoku] Teleotanais madara sp. nov. [New Japanese name: Madara-tanaisu] ( Figs 1–3 )

Diagnosis. Antennule darkly pigmented; article 2 with mid-inner simple seta. Antennal article 3 with single simple seta in distal region. Maxilliped with endite bearing distal serrate-tipped curved-spiniform seta and subdistal serratetipped spiniform seta in inner dorsal region; palp article 4 with mid-outer simple seta. Cheliped with fixed finger bearing one or two ventral simple setae; dactylus with two subproximal simple setae on cutting surface. Pereopod-1 merus with two ventrodistal simple setae being half as long as width of merus. Dactylus–unguis of pereopods 4–6 not fused. Uropod with basal article bearing two ventral simple setae; endopod biarticulate.

Etymology. This species-group name is derived from the Japanese noun madara (mottled), referring to the mottling on the body.

Material Examined. Holotype: ovigerous female, ICHUM-5844, BL 2.58 mm, CW 0.35 mm, dissected, eight slides and one vial; INSD accession number LC472886 ; mouth of Shiira River (24°19′25.1″N 123°54′38.3″E), Iriomote Island, Ryukyu Islands, southwestern Japan, mud on mangrove roots, 23.ii.2017, collected by Y. Tanabe. Paratypes: three preparatory females (ICHUM-5845, BL 1.66 mm, CW 0.25 mm, dissected, six slides and one vial; ICHUM-5846, BL 2.50 mm, CW 0.29 mm, dissected, nine slides and one vial; ICHUM-5847, BL 2.55 mm, CW 0.30 mm, dissected, six slides and one vial); same collection data as for holotype.

Description of female. Based primarily on ICHUM- 5844, with some observations from ICHUM-5845–5847.

Body ( Figs 1 , 2A, B ) dorsoventrally flattened, seven times as long as CW, pigmented red-brown ( Fig. 1 ; pigmentation retained in ethanol). Cephalothorax length 0.16 times as long as BL, length 1.23 times width, with pair of simple setae posterior to eyes and pair of mid-lateral simple setae. Pereonites 1–6 with length ratio 1.00: 1.10:1.18: 1.33:1.23: 1.04; pereonites with pair of lateral simple setae. Pleon length 0.16 times BL. Pleonites all wider than long, with pair of dorsal simple setae; pleonites 1–4 with pair of mid-lateral circumplumose setae ( Fig. 2B 1 ); pleonite 5 with two pairs of simple mid-lateral setae. Pleotelson length 0.72 times width, as wide as pleonites, with three pairs of lateral simple setae and pair of posterior simple setae.

Antennule ( Fig. 2C ) 0.80 times as long as cephalothorax; articles 1–4 with length ratio 1.00: 0.38: 0.31: 0.43. Article 1 with outer distal simple seta and several outer subproximal and outer distal PSS. Article 2 with one mid-inner, one outer distal, and one inner distal simple setae and several distal PSS. Article 3 with one outer distal and one inner distal simple setae. Article 4 with several simple setae and two aesthetascs in distal region. Antenna ( Fig. 2D, L ) with six articles (article 1 fused to cephalothorax; Fig. 2L , arrowhead), 0.95 times as long as antennule; articles 2–6 with length ratio 1.00: 2.60: 2.03: 1.39: 0.33. Articles 1 and 2 naked. Article 3 with one dorsosubproximal, one mid-dorsal, and one dorsodistal simple setae. Article 4 with one dorsodistal and one ventrodistal simple setae and several PSS. Article 5 with one mid-ventral and one dorsodistal simple setae and distal PSS. Article 6 with five distal simple setae.

Labrum ( Fig. 2E ) not projected anteriorly, setulate distally. Mandibles ( Fig. 2F, G ) with well-developed conical molar process, denticulate in masticatory region. Left mandible ( Fig. 2F ) with denticulate incisor and denticulate lacinia mobilis. Right mandible ( Fig. 2G ) with bifurcate incisor, subdistal anterior margin crenulate. Labium ( Fig. 2H ) with inner and outer lobes setulate on distal margin; outer lobe much larger, without labial process. Maxillular ( Fig. 2I ) endite with eleven spiniform setae, and outer subdistal setation; palp broken. Maxilla ( Fig. 2I , arrowhead) naked. Maxilliped ( Fig. 2J, J1–3 ) with medially fused basis bearing ventral simple seta at insertion of palp (seta reaching beyond distal margin of endite). Endite ( Fig. 2J 1 ) with outer distal simple seta, and three (left) or two (right) distal spiniform setae; inner dorsal region with distal serrate-tipped curvedspiniform seta ( Fig. 2J2 ) and subdistal serrate-tipped spiniform seta ( Fig. 2J 3 ); inner ventral region with distal round- ed bulge. Palp article 1 naked; article 2 with one (right) or zero (left) outer and four inner simple setae; article 3 with ten inner simple setae; article 4 with nine distal and one mid-outer simple setae. Epignath ( Fig. 2K ) narrow, curved, with fine setae distally.

Cheliped ( Fig. 3A, A 1 ) broadly articulated with cephalothorax via sclerite ( Fig. 2B ); sclerite extending to posterior margin of cephalothorax. Basis almost as long as wide, with slight free posterior portion and outer dorsal simple seta. Merus with ventral simple seta. Carpus as long as propodus including fixed finger, with one dorsodistal and two ventral simple setae. Propodal palm longer than fixed finger, with one outer and four inner simple setae at insertion of dactylus. Fixed finger with two simple setae on ventral margin; cutting surface with four outer and one inner simple setae, and outer lamellar expansion; triangular claw present. Dactylus (note: proximal portion partly broken in Fig. 3A, A 1 ) as long as fixed finger, with inner subproximal simple seta; cutting surface with two subproximal simple setae; unguis fused to dactylus.

Pereopod 1 ( Fig. 3B ) with length ratio of basis, ischium, merus, carpus, propodus, and dactylus–unguis 1.00: 0.07: 0.41: 0.29: 0.63: 0.57. Coxa with simple seta. Basis cylindrical, length 3.56 times width, with simple seta and two PSS in dorsosubproximal region. Ischium with ventral simple seta. Merus with two ventrodistal simple setae being half as long as width of merus. Carpus with four distal simple setae. Propodus with four subdistal simple setae. Dactylus with subproximal simple seta. Unguis 1.11 times as long as dactylus, naked. Pereopod 2 ( Fig. 3C ) with length ratio of articles from basis to dactylus–unguis 1.00: 0.05: 0.25: 0.28: 0.50: 0.55. Coxa with simple seta. Basis cylindrical, narrow, length 3.41 times width, with one simple seta and PSS in dorsosubproximal region. Ischium with ventral simple seta. Merus with ventrodistal simple seta. Carpus with three distal simple setae. Propodus with four subdistal simple setae. Dactylus with subproximal simple seta. Unguis as long as dactylus, naked. Pereopod 3 ( Fig. 3D ) with length ratio of articles from basis to dactylus–unguis 1.00: 0.09: 0.27: 0.35: 0.59: 0.70. Similar to pereopod 2, except basis without dorsal simple seta. Pereopod 4 ( Fig. 3E ) with length ratio of articles from basis to dactylus–unguis 1.00:0.03:0.42:0.24:0.41:0.28. Coxa present, with simple seta. Basis thick, length 2.53 times width, with two dorsosubproximal and two ventrodistal PSS. Ischium with ventral simple seta (note: hinge between ischium and merus disjointed in Fig. 3E ). Merus with two ventrosubdistal spiniform setae. Carpus with dorsodistal simple seta and three distal spiniform setae. Propodus with three dorsosubdistal simple setae, dorsal PSS, and two ventrosubdistal spiniform setae. Dactylus with dorsal simple seta. Unguis naked. Pereopod 5 ( Fig. 3F ) with length ratio of articles from basis to dactylus–unguis 1.00: 0.06: 0.49: 0.35: 0.50: 0.39. Similar to pereopod 4, except coxa naked, basis without PSS, and ischium with two ventral simple setae. Pereopod 6 ( Fig. 3G ) with length ratio of articles from basis to dactylus–unguis 1.00: 0.07: 0.27: 0.37: 0.37: 0.34. Similar to pereopod 4, except coxa naked, basis without ventrodistal PSS, propodus with nine dorsodistal simple setae, and dactylus with two dorsal simple setae (note: distal portion of carpus partly broken in Fig. 3G ).

Pleopod 1 ( Fig. 3H 1 , H 2 ) with basal article bearing inner plumose seta. Endopod with one inner and nine outer plumose setae, and distal step-tipped seta. Exopod 1.11 times as long as endopod, with 19 outer plumose setae. Pleopods 2–5 similar to pleopod 1, except for numbers of plumose setae on outer margin of endopod and exopod, and pleopod 5 endopod having two inner plumose setae.

Uropod ( Fig. 3I ) biramous. Basal article with two ventrodistal simple setae. Endopod biarticulate; article 1 with dorsodistal simple seta; article 2 with four distal simple setae. Exopod biarticulate; article 1 with distal simple seta; article 2 with two distal simple setae.

Variation and stability. In addition to the holotype, three female paratypes were dissected and data were obtained for the same 13 characters as listed in Table 1. Among the four specimens, the character states for eleven of the characters were identical ( T. madara column, Table 1); the exceptions were the number of distal spiniform setae on the maxillipedal endite (two on the right endite in the holotype; three in the others), and the ventral simple setae on the fixed finger (one in ICHUM-5845; two in the others).

Genetic information. Part of the COI gene (652 nt, translating into 217 amino acids) was determined from the holotype female. The three sequences in the INSD most similar to the COI sequence, as determined by BLAST searches ( Altschul et al. 1990), were from two insect and one spider species ( INSD accession numbers KJ837447, JF411102, and DQ353285; 77.57–78.62% in identity scores) but their query cover was only 41–65 %. To date, no other teleotanaid nucleotide sequences have been deposited in public databases ( DDBJ 2019 ) .

Figures

Fig. 1. Teleotanais madara sp. nov., holotype female (ICHUM-5844), ethanol fixed specimen, dorsal (A) and left (B) views. Scale: 1mm.

Fig. 2. Teleotanais madara sp. nov., female. A–J, J1–3, holotype (ICHUM-5844); K, paratype (ICHUM-5846); L, paratype (ICHUM-5847). A, body, dorsal view; B, body, lateral view; B1, mid-lateral circumplumose seta on pleonite; C, left antennule, dorsal view; D, left antenna, outer view; E, labrum; F, G, left and right mandibles, respectively; H, labium; I, maxillule and maxilla (arrowhead); J, maxillipeds, dorsal view (setae omitted from left palp and inner dorsal region of endite); J1, distal portion of maxillipedal endite, dorsal view; J2, serrate-tipped curved-spiniform seta; J3, serrate-tipped spiniform seta; K, epignath; L, proximal portion of right antenna, outer view (arrowhead, article 1 fused to cephalothorax). Scales: A, B, 1mm; B1, J2, J3, 0.01mm, others, 0.1mm.

Fig. 3. Teleotanais madara sp. nov., female. A, A1, E, G, H1, H2, I, holotype (ICHUM-5844); B–D, F, paratype (ICHUM-5845). A, left cheliped (proximal portion of dactylus partly broken), outer view; A1, same, fixed finger and dactylus; B–G, right pereopods 1–6; H1, basal article and endopod of right pleopod 1, most setal ornamentation omitted; H2, distal portion of basal article and exopod of right pleopod 1, most setal ornamentation omitted; I, right uropod, outer view. Black arrowheads, broken portion on dactylus; white arrowhead, broken potion on carpus. Scales: 0.1mm.