Tumidochelia knighti Larsen & Shimomura, 2007, n. sp.
Creators: name: Larsen, Kim
name: Shimomura, Michitaka
Publisher: name: Zenodo
Year: 2007
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Tanaidacea
Akanthophoreidae
Tumidochelia
Tumidochelia knighti

description: Tumidochelia knighti n. sp.
(Figs 1 and 2)
Material examined. Holotype, non-ovigerous female (KMNH IvR 700.166), Station 8, 26°26.63’N, 127°33.04’E, 654– 635 m, sand, Northwest of Cape Zanpa, Okinawa, 27 May 2006. Paratype, 1 non-ovigerous female (KMNH IvR 700.167), dissected, same locality.
Diagnosis. Female. Pereonites 2 and 3 longer than wide, pereonite 2 longest. Pleotelson shorter than combined length of three pleonites. Antenna with five articles, article 3 longer than other articles, without fusion line. Mandibular molar tapering abruptly, with one anterior spine at apex.
Male. Unknown.
Etymology. The species is named after Ms. Julianne Knight who described the genus Tumidochelia.
Description (body of holotype, appendages of dissected paratype).
FEMALE.
Body (Fig. 1 A, B). Body length 3.6 mm. Sub-cylindrical, elongate, approximately 9.5 times longer than wide.
Cephalothorax. Longer than wide (l/w 1.5) with no pronounced spines or setae.
Pereonites. Pereonites 1 and 6 wider than long. Other pereonites longer than wide, pereonites 2 longest.
Pleonites. All wider than long, subequal, bearing pleopods.
Pleotelson. Shorter than combined length of three pleonites.
Antennule (Fig. 1 C). With four articles. Stout at base tapering distally, almost as long as carapace. Article 1 with one simple distal seta and three subdistal setulated setae; article 2 approximately 0.80 times as long as article 1, with two simple distal setae; article 3 approximately 0.3 times length of article 2, with one simple distal seta; article 4 narrowing distally, approximately twice length of article 3, with six simple distal setae.
Antenna (Fig. 1 D). With five articles. Approximately 0.7 times as long as antennule. Article 1 wider than other articles, with dorsodistal process and one distal seta; article 2 band-shaped, with one distal seta, Article 3 longer than other articles, without fusion line, with one distal seta; article 4 with two simple distal setae; article 6 approximately 0.25 length of article 5, with three simple distal setae.
Mouthparts. Relatively small (mandibular body less than 0.1 mm), considering size of entire animal, mouthparts are very small. Labrum (Fig. 1 E) apex pointed, apparently naked. Mandibles (Fig. 1 F, f1, G) molar of intermediate width, tapering abruptly, anterior spine at apex. Left mandible (Fig. 1 G) incisor narrow, with three distal denticles; lacinia mobilis blunt. Right mandible (Fig. 1 F, f1) incisor with two rows of several acute denticles. Labium (Fig. 1 H) with one pair of lobes, with small acute process at outer corners. Maxillule (Fig. 1 I) endite with seven terminal spiniform setae of which two are setulose; palp not recovered. Maxilla (Fig. 1 J) narrow and fairly large (half as long as maxillule endite). Maxilliped (Fig. 1 K) endites with blunt distal process, fairly wide (almost as wide as basis). Basis fused. Palp article 1 naked; article 2 with two inner setae; article 3 with three inner setae; article 4 with four setae. Epignath not recovered.
Cheliped (Fig. 2 A). Attached to cephalothorax by a large sclerite. Basis naked, narrow in posterior part, approximately as long as carpus. Merus with two ventral setae. Carpus widening distally, with two small dorsal setae and one simple ventrodistal seta, ventrodistal part inflated, extending distally past propodus articulation. Propodus shorter than basis, with two simple ventral setae mid-length, and three small distal setae proximal to fixed finger. Fixed finger displaying two spines and three setae on inner margin. Dactylus large, with one dorsoproximal seta.
Pereopod 1 (Fig. 2 B). Longer than other pereopods. Coxa with one seta. Basis robust without seta. Ischium with one simple distal seta; merus widening distally, longer than carpus, with two ventrodistal setae. Carpus rectangular, half as long as propodus, with two spiniform distal setae. Propodus elongate, longer than merus, with one spiniform ventro-subdistal seta, ventral margin with row of small spines and dorsal spine. Dactylus and unguis approximately 0.4 times length of propodus, dactylus with distal spine at unguis insertion. Unguis as long as dactylus.
Pereopod 2 (Fig. 2 C). As pereopod 1 except: smaller; coxa naked; merus shorter; carpus with two spiniform and two simple distal setae; dactylus with only one spine.
Pereopod 3 (Fig. 2 D). As pereopod 2 except: dactylus smooth.
Pereopod 4 (Fig. 2 E). As pereopod 2 except: propodus with three spiniform distal setae; dactylus (including unguis) as long as propodus, with ventral serration; unguis less than 0.3 times as long as dactylus.
Pereopod 5 (Fig. 2 F). As pereopod 4 except: basis without seta; dactylus with notches extending the full length of posterior margin.
Pereopod 6 (Fig. 2 G). As pereopod 4 except: propodus, with four distal setae.
Pleopods (Fig. 1 L). Basal article smooth. Endopod rectangular, with numerous simple distal setae. Exopod rectangular, with one robust proximal seta, and numerous simple distal setae.
Uropods (Fig. 1 M). Biramous, basal article naked, with dorsomedial spiniform process. Endopod with two subequal articles; article 1 with two simple distal setae; article 2 with four simple distal setae. Exopod only reaching just beyond midlength of first endopod article, with two subequal articles; article 1, with one simple distal seta; article 2 with two simple distal setae.
Remarks. Tumidochelia knighti can be separated from T. unicinata by the long pereonites 2 and 3 and the pleotelson being shorter than combined length of three pleonites. From T. randyi the new species can be discriminated by the short pleotelson and the antenna article 3 longer than other articles being without fusion line. The structure of the mandibular molar also shows a difference in the abrupt tapering and fewer apical spines. Tumidochelia knighti strongly resembles T. dentifera G.O. Sars (1896) but can be separated by the lack of fusion line and a shorter uropodal exopod. Also the geographical distribution would be unlikely for one species.
The antenna consists of five articles in T. knighti while T. randyi is described as having six (Knight et al. 2003). However, there is some uncertainty about the condition of T. randyi as no complete antenna was recovered (Knight et al. 2003:500); also the presence/absence of a fusion line can confuse the issue as some workers might count the pseudoarticulation as a real articulation.
description: Published as part of Larsen, Kim & Shimomura, Michitaka, 2007, Tanaidacea (Crustacea: Peracarida) from Japan. II. Tanaidomorpha from the East China Sea, the West Pacific Ocean and the Nansei Islands, pp. 1-43 in Zootaxa 1464 on pages 4-7, DOI: 10.5281/zenodo.176517