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Bibliographic Details
Main Authors:	Horton, Tammy, Valls Domedel, Georgina, Hendrycks, Ed A.
Format:	Recurso digital
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Published:	Zenodo 2026
Subjects:	Biodiversity Taxonomy Animalia Arthropoda Malacostraca Amphipoda Tryphosidae Thrombasia Thrombasia ania
Online Access:	https://doi.org/10.5281/zenodo.19208906
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Thrombasia ania sp. nov.Figs 1, 2, 3, 4, 5Type material.Holotype: Pacific • male, 3.5 mm, carcass and three slides; Clarion-Clipperton Zone; 11.791°N, 117.537°W; depth 4352 m; 09 / 05 / 2018; BGR contract area, RV " Sonne ", Cruise MANGAN 2018, Station SO 262-155, epibenthic sledge; SMF 63365. Paratype: PACIFIC • sex unknown, (damaged) ~ 4.5 mm, carcass and one slide; Clarion-Clipperton Zone; 11.791°N, 117.537°W; depth 4352 m; 09 / 05 / 2018; BGR contract area, RV " Sonne ", Cruise MANGAN 2018, Station SO 262-155, epibenthic sledge; SMF 63366; • male, 5 mm, used for CLSM; Clarion-Clipperton Zone; 11.823°N, 117.544°W; depth 4340 m; 09 / 05 / 2018; BGR contract area, RV " Sonne ", Cruise MANGAN 2018, Station SO 262-156, epibenthic sledge; SMF 63367.Other material.Pacific • unsexed (head only), not measured; Clarion-Clipperton Zone; 11.83°N, 117.508°W; depth 4344 m; 09 / 05 / 2016; BGR contract area, RV " Kilo Moana ", Cruise MANGAN 2016, Station Ma 16-91, epibenthic sledge; DSB_3678; • unsexed, 2 mm; Clarion-Clipperton Zone; 11.798°N, 117.511°W; depth 4356 m; 09 / 05 / 2016; BGR contract area, RV " Kilo Moana ", Cruise MANGAN 2016, Station Ma 16-95, epibenthic sledge; DSB_3679 • immature male, (damaged) ~ 3 mm; Clarion-Clipperton Zone; 11.791°N, 117.537°W; depth 4352 m; 09 / 05 / 2018; BGR contract area, RV " Sonne ", Cruise MANGAN 2018, Station SO 262-155, epibenthic sledge; DSB_3611 • unsexed, 2.5 mm; Clarion-Clipperton Zone; 11.823°N, 117.544°W; depth 4340 m; 09 / 05 / 2018; BGR contract area, RV " Sonne ", Cruise MANGAN 2018, Station SO 262-156, epibenthic sledge; DSB_3615 • unsexed, 2 mm; Clarion-Clipperton Zone; 11.823°N, 117.544°W; depth 4340 m; 09 / 05 / 2018; BGR contract area, RV " Sonne ", Cruise MANGAN 2018, Station SO 262-156, epibenthic sledge; DSB_3617 • unsexed, 2.5 mm; Clarion-Clipperton Zone; 11.823°N, 117.544°W; depth 4340 m; 09 / 05 / 2018; BGR contract area, RV " Sonne ", Cruise MANGAN 2018, Station SO 262-156, epibenthic sledge; DSB_3618.Type locality.Abyssal Pacific Ocean, Clarion-Clipperton Zone; 11.791°N, 117.537°W; depth 4352 m.Diagnosis.Lateral cephalic lobe broadly triangular, apically subacute; process of upper lip broadly rounded and weakly protruding in front of epistome; coxa 1 weakly tapering, broad, about as long as coxa 2; gnathopod 1 propodus with acute palm, palm margin slightly concave; gnathopod 2 carpus length 1.6 × propodus; coxa 4 posteroventral lobe rounded; pereopod 7 basis length 1.7 × width; epimeron 3 posteroventral corner acute, slightly produced; uropod 2 inner ramus, spine at constriction not reaching end of ramus; uropod 3 outer ramus, article 2 long, length 0.9 × article 1; telson short, length 1.2 × width, cleft 29 %, lobes closely appressed.Description.Based on holotype male, 3.5 mm SMF 63365; and paratypes SMF 63367 and SMF 63366, where indicated.Body (Figs 1, 2): Pereonites 1–7 (Fig. 1 A) smooth, deeper than long, successively longer. Pleonite 3 (Fig. 1) with a rounded, posterodorsal elevation slightly overhanging urosomite 1. Urosomite 1 (Fig. 1 A) proximally broadly rounded, with a middorsal concavity. Urosomite 2 (Fig. 1 A) short, but not telescoped under urosomite 1. Epimeron 1 (Figs 1 A, 2): quadrate, anterodistal corner slightly narrow, posterior margin broadly rounded. Epimeron 2 (Figs 1 A, 2) subquadrate, anterodistal corner rounded, distal margin convex, posterodistal corner not produced, posterior margin straight. Epimeron 3 (Figs 1 A, 2) anterodistal corner rounded, ventral margin convex, posterodistal corner slightly prolonged acutely into a broad tooth, posterior margin slightly convex. Coxae 1–4 (Figs 1 A, 2) longer than corresponding pereonites, progressively longer, coxa 1 subequal to coxa 2, slightly tapered distally.Head (Figs 1, 2): subequal in length to pereonites 1–2; rostrum short, not reaching half of lateral cephalic lobe. Lateral cephalic lobe (Figs 1 A, 1 B, 2) broadly triangular, subacute. Eye (Fig. 1 B) appearing white in fresh specimen, but not apparent in preserved specimens, non-ommatidial, formed of pigment granules; somewhat pear-shaped and occupying much of the lateral cephalic lobe, extending up to antenna 1 insertion. Antenna 1 short, length 0.2 × body; peduncular article 1 dilated, length 1.2 × width (SMF 63367 = 1.5 ×), lacking dorsal keel; peduncular articles 2–3 short; flagellum nine-articulate, with small setae, first article of flagellum callynophorate, furnished medially with double row of aesthetascs; accessory flagellum four-articulate, first article broader and longer than remaining articles combined, calceoli absent. Antenna 2 approximately equal to antenna 1, gland cone small: peduncular article 4 longer than 5, with short posteromedial setae; flagellum 22–23 - articulate, calceoli absent.Mouthparts (Fig. 3): Epistome (of paratype SMF 63366) weakly convex. Upper lip process broadly rounded and weakly protruding in front of epistome, ventral margin rounded, with fine setules. Mandible incisor convex and widened, with tooth at anterodistal and posterodistal corners; left lacinia mobilis serrate, about 8 - dentate, right lacinia mobilis lacking; left accessory spine row broken, right with three spines; molar ovate and strongly triturative, margin ridged, surface with three pits; palp attached level with molar, article 2 1.7 × length of article 3, with five A 2 - setae, article 3 narrowly ovate, 0.6 × length of article 2, with one A 3, seven D 3 - pectinate setae and two E 3 - setae. Lower lip outer lobes broad with margins setose; inner lobes lacking, mandibular lobes narrow, rounded. Maxilla 1 inner plate rectangular, narrow with two stout apical plumose setae; outer plate broad, with 11 spine-teeth in 6 / 5 crown arrangement; palp 2 - articulate, article 2 rectangular, with six stout contiguous serrated spines and one longer marginal spine. Maxilla 2 inner plate slightly shorter and broader than outer tapering distally, both with row of pectinate medial marginal spines and setae. Maxilliped inner plate narrow, subrectangular, extending well past the distal end of the inner margin of palp article 1 and not reaching one-half of outer plate, distal margin with three nodular triangular spines and plumose setae; outer plate narrowly subovate, length 2.1 × width, extending to the distal end of palp article 2, with three strong distal spatulate spines and five strong medial nodular spines; palp setose medially, article 2 longest, article 4 slightly shorter than article 3.Pereon (Figs 2, 4): Gnathopod 1 (Fig. 2) coxa 1 weakly tapering, length 1.8 × width, anterior margin slightly convex, anterodorsal corner rounded, posterior margin slightly convex, distal margin straight; basis, anterior margin with short setae distally; ischium subequal to merus; carpus without lobe, length 1.3 × propodus, posterodistal margin setose; propodus short, length 1.7 × width, subchelate, palm acute, slightly concave, palmar corner defined by two long spines; dactylus narrow, overriding palm corner. Gnathopod 2 (Fig. 2) coxa rectangular, length 1.6 × width; basis narrow, length 6.3 × width, margins lacking setae; ischium longer than merus; carpus length 1.6 × propodus, setose; propodus subovate, subchelate, with anterodistal groups of long pectinate setae, hind margin setose, palm short, nearly transverse; dactylus stout, not overriding palm corner. Pereopod 3 (Fig. 4) coxa rectangular, with anterior margin very slightly convex, posterior margin slightly concave, length 2 × width; merus longer than carpus, posterior margins with long setae; propodus longer than carpus, posterior margin weakly setose; dactylus straight, long, length 0.7 × propodus. Pereopod 4 (Fig. 4) coxa length 1.4 × width, anterior margin convex, posterior margin deeply excavate proximally, with rounded posterodistal lobe located at distal 59 % of the coxa length, ventral margin slightly convex; rest of pereopod articles as in pereopod 3 (dactylus missing). Pereopod 5 (Fig. 4) coxa posterolobate, length 1.2 × width, anterior and posterior margins rounded; basis, length 1.9 × width, anterior margin spinose, posterior margin straight, slightly serrate, with narrow posterodistal lobe extending to or just beyond end of ischium; merus weakly expanded; remaining articles missing. Pereopod 6 (of paratype SMF 63366) (Fig. 4) coxa posterolobate, subtriangular, posterior margin straight, lobe rounded; basis, length twice width, anterior margin straight with small spines distally, posterior margin straight with fine setules, posterodistal lobe just reaching end of ischium, ischium anterior margin with long setae; merus shorter than carpus; propodus narrow, shorter than carpus, with weak spines; dactylus slightly curved, length 0.5 × propodus. Pereopod 7 (of paratype SMF 63366) (Fig. 4) coxa posterolobate, subtriangular, posterodistally rounded; basis broadly expanded, length 1.7 × width, anterior margin with weak spines distally, posterior margin convex, with small serrations and setules, posterodistal lobe just reaching end of ischium; merus-propodus as in pereopod 6 but narrower; propodus longer than carpus.Urosome (Fig. 5): Uropod 1 peduncle length 1.4 × rami, dorsolateral and dorsomedial margins spinose, with four and six spines respectively; rami lanceolate, equal in length, dorsolateral and dorsomedial margins with three spines. Uropod 2 peduncle slightly shorter than outer ramus, dorsolateral and dorsomedial margins with two and three spines respectively; rami lanceolate with apical inset spine, inner ramus shorter than outer ramus, constricted, long spine at constriction not reaching end of ramus, dorsolateral and dorsomedial margins with one spine; outer ramus, dorsolateral margin with three spines, tip broken off. Uropod 3 peduncle 0.6 × length of biarticulate outer ramus, with one dorsomedial and distoventral spine; second article of outer ramus very long, 0.9 × length of article 1, article 1 with two dorsolateral and one dorsomedial spine; inner ramus slightly shorter than outer, with one spine. Telson (Figs 1, 5) not reaching end of uropod 3 peduncle, short, length 1.2 × width, cleft 29 %, lobes closely appressed, with one apical spine in middle of lobe.Etymology.This species is named ‘ ania’, used as a noun in apposition, in honour of Anna Ja&zdot;d&zdot;ewska, in recognition of her contribution to deep-sea amphipod taxonomy, and for the efforts she made to bring our ‘ amphipod family’ together for the ISA SSKI workshop at the University of Lodz, Poland.Remarks.Thrombasia ania sp. nov. can be distinguished from all other species in the genus in having a small, broadly rounded process of the upper lip which scarcely protrudes in front of the epistome, and a long article 2 of uropod 3 (0.9 × article 1). All other Thrombasia species have a long, produced lobe extending strongly in front of the epistome and a short article 2 of uropod 3 (less than 0.53 × article 1).Thrombasia ania sp. nov. has an upturned tooth on epimeron 3, which is found in three other species in the genus; T. grabenis, T. tracalero and T. umina. Thrombasia ania sp. nov. differs from T. grabenis in the uropod 2 incised spine length (longer in T. grabenis reaching the end of the ramus versus not reaching in T. ania sp. nov.), the outer ramus uropod 3 article 2 (longer in T. ania sp. nov. than in T. grabenis) and the telson which is more deeply cleft in T. grabenis (44 % versus 29 % in T. ania sp. nov.). The two species can also be separated by characters of the gnathopod 1 and 2. The maxilliped outer plate distal teeth are also more robust in T. ania sp. nov. than in T. grabenis.The mandibular molar of Thrombasia tracalero is asymmetrical, proximally setose and distally triturating and thus differs from all other members of the genus which have a columnar molar with an oval fully triturating surface. Thrombasia ania sp. nov. also differs from T. tracalero in the shorter more shallowly cleft telson with closely appressed lobes (versus longer and more deeply cleft with apices separated in T. tracalero). The two species can also be separated by characters of the gnathopod 2.Thrombasia ania sp. nov. can be separated from T. umina by the coxa 1 which is strongly tapering in T. umina and only weakly so in T. ania sp. nov. The gnathopod 1 palm is also more acute in T. ania sp. nov.Only Thrombasia rotundata reaches abyssal depths where this new species is found, but that species is described from the South Atlantic. It also possesses a strongly protruding upper lip process (very weakly produced in T. ania sp. nov.), a short article 2 of uropod 3 outer ramus (very long in T. ania sp. nov.), a shorter truncated posterodistal lobe of coxa 4 (longer and broadly rounded in T. ania sp. nov.) and a narrowly rounded posterodistal corner of epimeron 3 (acutely produced in T. ania sp. nov.)Distribution.Abyssal Pacific Ocean, Clarion-Clipperton Zone, 4340–4356 m.Molecular data.Sequence data for the holotype of Thrombasia ania sp. nov. is deposited in GenBank under accession number PQ 734300. The species has also received a Barcode Index Number from Barcode of Life Data Systems: BOLD: AEB 6138 (https://doi.org/10.5883/BOLD:AEB6138).

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