Chondrochelia corfortis, Bird, 2019

Bird, Graham J., 2019, Tanaidacea (Crustacea: Peracarida) from the Southern French Polynesia Expedition, 2014. I. Tanaidomorpha, Zootaxa 4548 (1), pp. 1-75 : 13-23

Chondrochelia corfortis n. sp.

( Figs 4–10 )

Leptochelia lifuensis Stebbing, 1900 : Nobili (1907): 414 (possible synonym).

Material examined. Holotype — non-ov. ♀, 4.4 mm, P.98941, Stn 66-3, Taravai, Gambier Islands, 23° 07' 51" S 135° 02' 05" W, green calcareous algae Halimeda sp., 10–16 m, 12 October 2014, coll. A. Reid, S.J. Keable, C. Sim-Smith, and C. Bedford.

Allotype —dimorphic (copulatory) ♂, 4.1 mm, P. 102321, Stn 66-3, details as for holotype.

Paratypes — GAMBIER ISLANDS: three non-ov. ♀♀ P.98937, Stn 65-3; one non-ov. ♀ P.98949, one non-ov. ♀ P. 100136, 35 non-ov. ♀♀, nine prep. ♀♀, seven ovigerous (ov.) ♀♀, three post-ovigerous (post-ov.) ♀♀ P. 102318, one non-ov. ♀ dissected maxilliped on microslide P.102318.001, seven cop. ♂♂ P. 102319, one small cop. ♂ cheliped dissected P. 102320, Stn 66-3; one non-ov. ♀ P.98955, 13 non-ov. ♀♀, two ov. ♀♀ P.99210, one prep. ♀ P. 102324, Stn 66-4; two manca-II, two manca-III, 41 non-ov. ♀♀, four prep. ♀♀, eight ov. ♀♀, one postov. ♀, seven cop. ♂♂ MA73583, one prep. ♀ dissected on two microslides P. 102322, P.102322.001, one cop. ♂ dissected on two microslides P. 102323, P.102323.001, Stn 66-A; one prep. ♀ P. 102317, Stn 68-3.

Diagnosis. Female. Cephalothorax 1.4 times ltb. Antennule article-1 about three times ltb; article-2 longest distal seta as long as article-2. Antenna article-1 with ventrodistal seta; article-2 dorsal spine longer than ventral; article-3 with dorsodistal spine only, without distolateral seta. Maxilliped bases with six setae; palp article-2 with lateral seta not on distinct apophysis. Cheliped basis dorsodistal margin without apophysis; propodus with five ventral setae. Pereopod-1 dactylus and unguis just longer than propodus. Pereopods 2–3 ischium with two setae; merus without superodistal setae; carpus with two small inferior spines. Pereopod-6 propodus with two inferodistal crotchets and eight superodistal setae. Uropod peduncle with distomesial seta; endopod five-segmented (mature individuals); exopod one-segmented, two-thirds length of segment-1 of endopod.

Male. Antennule article-1 0.75 times length of cephalothorax; article-2 0.5 times length of article-1; flagellum 8–10 segmented. Cheliped less than half length of body, without elongate carpus or chela; basis dorsodistal margin without apophysis; fixed finger just longer than palm, incisive margin with two triangular apophyses; dactylus proximal incisive margin not crenulate. Pereopods 2–3 ischium with two setae. Pereopods 5–6 basis with superior flange; carpus with four distal crotchets and two setae. Uropod peduncle with six distolateral setae; endopod fivesegmented; exopod weakly bi-segmented, longer than segment-1 of endopod.

Etymology. Combination of the Latin noun cor (heart) and adjective fortis (brave), referring to the survey’s vessel ‘ Braveheart ’ and its personnel.

Description. Holotype non-ovigerous female, 4.4 mm (P.98941). Habitus ( Fig. 4A ) slender, 7.2 times Cephalothorax ( Fig. 4A ) 1.4 times ltb, just longer than pereonites 1–2 combined, carapace entire lateral margins with seta just posterior to eye-lobe (but cheliped sclerite setae also visible in dorsal view); rostrum pointed, weakly produced; eyes conical, multifaceted, with dark pigment. Pereon with weakly convex margins of pereonites 1–6, all shorter than broad, 0.6, 0.6, 0.75, 0.9, 0.9, and 0.7 times ltb respectively, pereonite-6 slightly wider posteriorly, all with pair of anterolateral setae (also coxal setae visible in dorsal view in pereonites 1–5). Pleon just longer than broad, 17% of body length, epimera 1–4 with one seta, epimera-5 with three setae. Pleotelson as long as pleonite-5, slightly tapered, with slightly produced posterior margin, with deflexed apex bearing two long setae other setation as figured.

Paratype ovigerous female, 5.3 mm (P. 102322, P.102322.001). Antennule ( Fig.4B ) 0.8 times length of cephalothorax, five times ltb; article-1 0.6 times total length, 3.1 times ltb, lateral margin with three proximal PSS, two long setae with associated PSS (distalmost seta longer than article-2), and mesial margin with seta; article-2 2.2 times ltb, with two distal setae, one as long as article; article-3 0.9 times length of article-2, with two distal setae and aesthetasc; cap-like segment with three setae and a PSS. Antenna ( Fig. 4C ) 0.8 times length of antennule; article-1 with ventrodistal seta; article-2 as long as broad, distally flared, with slender dorso- and ventrodistal thorn-like spines and setulate dorsal margin; article-3 as long as article-2, with dorsodistal thorn-like spine; article- 4 3.7 times ltb, just longer than articles 2 and 3 combined, with one PSS and simple seta at midlength, and two simple distal setae (longer than articles 5–6 combined) and two PSS; article-5 almost length of article-3, with two unequal setae; article-6 with five setae .

Mouthparts. Labrum ( Fig. 4D ) typical, hood-shaped, setulate. Mandibles ( Fig. 4E–F ) typical of genus: left mandible ( Fig. 4E ) incisor crenate, lacinia broad and distally crenulate, molar with spinose-ridged and granulose apex; incisor of right mandible ( Fig. 4F ) weakly bifid, with crenulate distal margin, molar as in left mandible. Labium ( Figure 5A ) typical, outer lobes broader and just longer than inner, both distally setulate. Maxillule ( Fig.5B ) endite setulate on distal part, with ten or eleven crowded terminal spines and outer corona of finer setae and setules; palp with two setae (not illustrated). Maxilla not observed.

Maxilliped ( Fig. 5C–G ) combined bases as long as broad, each basis with up to six long setae (mature individuals). Endite distal margin with large blunt lateral seta, one blunt (medial) and two larger incisor-like tubercles, and with two hyaline pectinate spines (coupling hooks). Palp article-1 distolateral margin with one or more small setules; article-2 with lateral seta and four unequal mesial smooth setae, mesial margin finely setulate; article-3 larger than article-2, about twice as long as broad, with nine setae (in two rows) the majority semiarticulated and smooth; article-4 with superodistal seta and nine or ten apical finely pectinate setae. Epignath not observed.

Cheliped ( Fig. 6A–C ) coxal sclerite triangular, reaching posterior of cephalothorax, with seta (visible in dorsal view); basis posterior lobe reaching pereonite-1, 0.7 times length of anterior mass, latter with dorsolateral seta; merus with three dispersed ventral setae and small seta near basis; carpus twice as long as broad, with three dorsal setae and three ventral setae. Chela 0.8 times length of carpus and narrower, 2.2 times ltb; propodus palm dorsal and ventral margins typically sub-parallel, with slender spine near articulation with dactylus on strongly convex margin, and two mesial combs of six spines and setules respectively ( Fig 6B ); fixed finger half length of palm, with five ventral/mesial setae and three near incisive margin, incisive margin raised, undulate ( Fig 6C ); dactylus with proximomesial spine.

Pereopod-1 ( Fig. 7A–B ) coxa with seta (and oostegite bud in preparatory female); basis arcuate, 4.6 times ltb, with proximal superior seta and PSS; ischium with seta; merus 1.8 times ltb, distal margin oblique with carpus, with one superodistal seta and two inferodistal setae; carpus 0.9 times length of merus, with two superodistal setae, two distolateral and two inferodistal setae ( Fig.7B ); propodus 0.9 times length of merus and carpus combined, 4.2 times ltb, with three unequal superodistal setae and one inferodistal seta; dactylus 1.5 times longer than unguis, with proximal accessory seta; unguis with distal pore, together with dactylus just longer than propodus.

Pereopod-2 ( Fig. 7C ) coxa with seta (and oostegite bud in preparatory female); basis broader than in pereopod-1, three times ltb, with proximal superior seta and two PSS; ischium with two setae; merus 1.5 times ltb, with inferodistal spine and seta, and inferior spinules; carpus length of merus, 1.5 times ltb, with two superodistal setae, two short inferodistal crotchets (mesial weaker and more acuminate) and one seta, inferior margin spinulate; propodus 3.5 times ltb, just shorter than merus and carpus combined, with two superodistal and one mediodistal setae, and one inferodistal crotchet; dactylus with accessory seta, longer than unguis, together claw-like and 0.4 times length of propodus.

Pereopod-3 ( Fig. 7D ) like pereopod-2 but slightly shorter overall, merus and carpus about length of broad, propodus three times ltb, with one superodistal and one inferodistal setae.

Pereopod-4 ( Fig. 7E ) coxa without seta (and with oostegite bud in preparatory female, as figured); basis broader than in pereopods 2–3, 1.8 times as ltb, with superior groove and proximal inferior PSS; ischium heavily shielded by basis, with two unequal setae; merus geniculate, about twice length of broad, with two stout inferodistal crotchets, and inferior spinules; carpus about 0.75 times length of merus, subrectangular with three distal crotchets (one almost molariform) and two superodistal setae; propodus length of carpus, superior margin with rows of microtrichia, with one stout and three slender pectinate superodistal spines, and two inferodistal crotchets; dactylus and unguis claw-like, 0.7 times length of propodus.

Pereopod-5 ( Fig. 7F ) like pereopod-4 but slightly larger, basis with three inferior PSS, one superior PSS and one seta.

Pereopod-6 ( Fig.7G–I ) like pereopod-5 but basis with one superior PSS and one inferior seta; merus, carpus and propodus more slender; propodus with five pectinate and three slender superodistal spines, one longer than the rest ( Fig. 7J ).

Pleopod ( Fig. 6D ) peduncle shorter than broad, mesial margin with plumose seta; rami subequal, sub-ovate, endopod and exopod about 2.5–2.6 times ltb respectively; endopod mesial margin with plumose seta at mid-length, lateral margin with proximal plumose seta separated by small gap from fringe of 17 plumose setae, distalmost with whip-like tip; exopod lateral margin with proximal plumose seta separated by small gap from fringe of 26 plumose setae.

Uropod ( Fig. 6E ) peduncle 1.7 times ltb, with small distomesial seta; endopod five-segmented, segments 1–3 with two simple setae distally, segments 1–2 also with PSS, segment-4 with one simple seta and two PSS, segment- 5 with five unequal simple setae and two PSS; exopod one-segmented, about 0.7 times length of segment-1 of endopod, with one subdistal and two apical setae.

Intraspecific variation. Manca-II. Habitus generally like small non-ovigerous female but without pereopods- 6 and pleopods; length 1.0– 1.1 mm (n=2). Uropod endopod barely three-segmented (i.e. articulations weak).

Manca-III. Habitus like small non-ovigerous female but with rudimentary pereopods-6 and pleopods; length 1.3–1.4 mm (n=2). Uropod endopod three-segmented.

Juvenile. Habitus like small non-ovigerous female but with pleopods lacking setae; length 1.5 mm (n=1). Uropod endopod three-segmented.

Non-ovigerous female (or neuter), preparatory female, and ovigerous female. Length 1.5–5.4 mm, of which non-ovigerous females 1.5–5.1 mm (n=81), preparatory females 3.6–4.7mm (n=11), ovigerous females 4.0– 5.4 mm (n=18), and post-ovigerous females 4.5–5.3 mm (n=4). Maxilliped basis ( Fig. 5H–I ) with fewer setae in smaller individuals: two in individuals with three-segmented uropod endopod (body length 1.38–1.90 mm), three setae in individuals with three-segmented endopod (body length 1.78–2.30 mm), and four-segmented endopod (body length 1.79 mm). Uropod ( Fig. 6F–G ) endopod 3–5 segmented, size related: three-segmented with body length 1.46–2.37 mm (n=20), four-segmented 1.87–2.60 mm (n=5), five-segmented 2.31–5.08 mm (n=55); several individuals with endopods with n and n+1 segments.

Allotype male, 4.1 mm (P. 102321). Habitus ( Fig. 8A ) stout, 4.8 times ltb. Cephalothorax 1.2 times ltb, rostrum ( Fig. 8A–B ) broadly spatulate; anterolateral seta posterior to each prominent eyelobe. Pereon 51% of total length, outline irregular, pereonites all shorter than broad, pereonites 1–3 progressively longer, pereonite-4 longest, pereonites 5–6 progressively shorter; pereonite-1 with five or six anterolateral setae per margin (not including visible coxal seta), pereonites 2–3 with two setae, pereonites 4–6 with one seta. Pleon as long as broad, 21% of total length, tapering posteriorly; pleonites 1-4 epimera with one seta, pleonite-5 with two setae. Pleotelson ( Fig. 8A, C ) about as long as pleonite-5, with two lateral setae, two posterior setae, two posterior PSS and two apical setae.

Paratype male, 4.0 mm (P. 102323, P.102323.001). Antennule ( Fig. 8D ) about twice as long as cephalothorax; article-1 0.6 times total length of peduncle, 5.5 times ltb, with two distal setae and a PSS; article-2 2.6 times ltb, with two distal setae; article-3 0.6 times length of article-2, with two distal setae; flagellum of 8–10 segments (nine in allotype, dissected paratype with nine and ten), all except small terminal segment with three or four ventral aesthetascs, terminal segment with five unequal setae. Antenna ( Fig. 8E ) 0.4 times length of antennule; article-1 with ventrodistal seta; article-2 shorter than broad, distally flared, with slender dorso- and ventrodistal thorn-like spines; article-3 length of article-2, with dorsodistal thorn-like spine; article-4 4.5 times ltb, longer than articles 1– 3 combined, with one PSS and simple distal seta at midlength, and three distal setae and a PSS; article-5 0.8 times length of article-4, slender, eight times ltb, with two unequal setae; article-6 small, with four unequal setae .

Mouthparts atrophied or absent.

Maxilliped atrophied, bases small, triangular; palp possibly one-articled.

Cheliped ( Fig. 9A–B ) coxal sclerite triangular, reaching posterior of cephalothorax, with seta (visible in dorsal view); basis posterior lobe reaching pereonite-1, 0.3 times length of anterior mass, latter with dorsolateral seta; merus with three dispersed ventral setae; carpus three times ltb, slightly narrower distally and with shallow mesial and lateral distal shields, with four dorsal setae and three ventral setae. Chela as long and broad as carpus, 3.2 times ltb; propodus palm with lateral seta near articulation with dactylus, oblique mesial comb of 20 spines, the outermost longest ( Fig. 9B ); fixed finger about length of palm, with two subtriangular apophyses on incisive margin and long distal process bearing small terminal spine (brown, chitinous), with three lateral setae near incisive margin, two ventral setae and four distomesial setae; dactylus arcuate, with small proximomesial seta, and numerous spinules on incisive margin; unguis small, brown, and chitinous.

Pereopod-1 ( Fig. 10A ) coxa with seta; basis arcuate, 6.5 times ltb, with proximal superior seta and small PSS; ischium with seta; merus 2.5 times ltb, distal margin strongly oblique with carpus, with single superodistal and inferodistal setae; carpus length of merus, 2.5 times ltb, with six distal setae; propodus 0.9 times length of merus and carpus combined, 5.3 times ltb, with three unequal superodistal setae and one inferodistal seta, superior margin spinulate; dactylus 1.6 times longer than unguis, with proximal accessory seta and microtrichia, together with unguis 0.8 times length of propodus.

Pereopod-2 ( Fig. 10B ) coxa with seta; basis straight, slightly broader than in pereopod-1, 4.3 times ltb, with proximal superior seta and PSS; ischium with two unequal setae; merus 1.9 times ltb, with single superodistal and inferodistal setae; carpus 1.2 times longer than merus, 2.5 times ltb, with two superodistal setae, two short inferodistal crotchets (mesial weaker and more acuminate) and one seta, inferior and superior margins spinulate (microtrichia); propodus 5.4 times ltb, 0.8 times length of merus and carpus combined, with three superodistal setae and one inferodistal crotchet, inferior and superior margins spinulate (microtrichia); dactylus with accessory seta and microtrichia, longer than unguis, together claw-like and 0.4 times length of propodus.

Pereopod-3 ( Fig. 10C ) like pereopod-2 but slightly shorter overall, basis 3.8 times ltb; merus without superodistal seta and with inferodistal seta; propodus with two superodistal setae.

Pereopod-4 ( Fig. 10D ) coxa without seta; basis broader than in pereopods 2–3, 2.2 times as ltb, with superoproximal PSS; ischium short, with two unequal setae; merus geniculate, about twice length of broad, with two inferodistal crotchets; carpus about 1.5 times longer than merus, twice length of broad, subrectangular, with four distal crotchets (two closely-spaced, ventrodistal almost molariform) and two superodistal setae, superior and inferior margin spinulate (microtrichia); propodus 1.3 times longer than carpus, slender, five times ltb, with four superodistal setae, and two inferodistal crotchets, superior and inferior margin spinulate (microtrichia); dactylus and unguis claw-like, half length of propodus, dactylus longer than unguis and spinulate (microtrichia).

Pereopod-5 ( Fig. 10E ) like pereopod-4 but slightly larger, basis longer and wider, twice length of broad, with superior groove and laminar flange, without inferodistal seta.

Pereopod-6 ( Fig. 10F–H ) like pereopod-5 but basis slightly larger and 2.3 times ltb; with one superoproximal PSS; propodus with three superodistal setae and distal row of six slender distal spines, one longer than the rest.

Pleopod ( Fig. 9C ) like that of female but peduncle slightly longer than broad; endopod and exopod more slender, about 2.6 and 3.7 times ltb respectively; endopod lateral margin with fringe of 18 plumose setae; exopod lateral margin with continuous fringe of 27 plumose setae.

Allotype copulatory male. Uropod ( Fig. 8C ) like that of female but peduncle with five or six inferior setae, endopod segment-1 shorter, and exopod more slender, weakly two-segmented.

Small copulatory male, 2.5 mm (P. 102320) similar to allotype male but antennule flagellum 8-segmented. Cheliped ( Fig. 9D ) similar to large male but chela proportionately slightly smaller and less elongate (2.9 times ltb). Uropod endopod 5-segmented.

Body length of other copulatory males 2.4–4.3 mm (n=14).

Distribution and habitat. Mangareva and Taravai, Gambier Islands, coral rubble, and green calcareous alga Halimeda , 5– 16m.

Remarks. Adding to the list of Chondrochelia species, C. corfortis n. sp. exhibits the suite of characters diagnosed by Guţu (2016) yet can be distinguished from the other Indo-Pacific species by its own combination of character-states ( Table 5). Females of C. corfortis share a similar uropod morphology to that of C. acrolophus (the most similar species), C. billambi (Błażewicz-Paszkowycz & Bamber, 2012) , C. distincta , and C. opteros ( Bamber, 2008) but is variously distinguished by its six maxilliped basis setae (shared only with C. distincta ), longer antennule article-2 seta, shorter antenna article-2 ventral spine, and pereopods 2–3 ischial and meral setation. Males of C. corfortis also conform to the generic diagnosis and are similar to those of other species ( Table 6) but may be closest to C. acrolophus and C. opteros in having flanges on the basis of the posterior pereopods (pereopods 5–6 in this instance).

A puzzle remains about the records of Alloleptochelia erythraea and L. lifuensis (currently accepted as Chondrochelia dubia (Krøyer, 1842)) from French Polynesia by Nobili (1907). The first species was described from the Red Sea ( Kossmann 1880, cited by Nobili 1907 and others; see Anderson 2016) and has now been transferred from its previous existence as a Leptochelia species by Guţu (2016), the males having more elongate chelipeds than in Chondrochelia . It is possible that an Alloleptochelia species, very doubtfully A. erythraea , remains to be rediscovered in French Polynesian waters; Seurat’s collection comprised a single male (locality in Tuamotus not known). In contrast, Nobili (1907: 414) states that L. lifuensis was very abundant in Gambier habitats (Taku and Mangareva on Mangareva Island, at 1–8m in Halimeda , coralline and calcareous algae, and pearl oysters), and at Tikehau Atoll (northwestern-most locality in the Tuamotu group) also in pearl oysters. The original description of L. lifuensis , from New Caledonia, by Stebbing (1900: 616–618, plates 54–55) shows the female antenna with a strong ventral spine on article-3 and two-segmented uropod exopods, both unlike the states seen in C. corfortis . Nevertheless, it is highly likely that the Nobili identification should refer now to this new species rather L. lifuensis .

Figures

FIGURE 4. Chondrochelia corfortis n. sp. non-ovigerous female holotype (P.98941). A, habitus. Non-ovigerous female paratype (P.102322, P.102322.001). B, antennule; C, antenna; D, labrum, E–F left and right mandibles respectively. Scale bars: habitus 1 mm, others 0.1 mm.

FIGURE 5. Chondrochelia corfortis non-ovigerous female paratype (P.102322, P.102322.001). A, labium, B, maxillule endite; C, maxilliped bases and endites; D, maxilliped endites; E, maxilliped endites, enlarged. Non-ovigerous female paratype (P.102318.001). F, maxilliped palp articles 1–3; G, maxilliped palp article-4. Small neuter paratype, 1.6 mm. H, maxilliped basis distal setae. Small neuter paratype, 1.84 mm. I, maxilliped basis distal setae. Scale bars: 1 mm.

FIGURE 6. Chondrochelia corfortis non-ovigerous female paratype (P.102322, P.102322.001). A, right cheliped; B, left chela, mesial comb and proximal dactylus; C, enlargement of fixed finger, setae omitted for clarity; D, pleopod (all setae plumose, many omitted for clarity); E, uropod. Small neuter, 1.6 mm. F, uropod. Small neuter, 1.84 mm. G, uropod. Scale bars: 0.1 mm.

FIGURE 7. Chondrochelia corfortis non-ovigerous female paratype (P.102322, P.102322.001). A, pereopod-1; B, same, alternative setation of carpus; C–G pereopods 2–6 respectively, E–F with detail of obscured carpal spines; H, pereopod-6 carpus, enlargement; I, pereopod-6 propodus and claw, enlargement. Scale bars: 0.1 mm.

FIGURE 8. Chondrochelia corfortis male allotype (P.102321). A, habitus; B, anterior of cephalothorax; C, pleotelson and uropods. Male paratype (P.102323, P.102323.001), D, antennule; E, antenna. Scale bars: habitus 1 mm, others 0.2 mm.

FIGURE 9. Chondrochelia corfortis male paratype (P.102323, P.102323.001). A, right cheliped; B, left chela; C, uropod (all setae plumose). Small male paratype (P.102320). D, cheliped. Scale bars: 0.5 mm, except D 0.2 mm. P.102320

FIGURE 10. Chondrochelia corfortis male paratype (P.102323, P.102323.001). A–F, pereopods 1–6 respectively, B and D with detail of obscured carpal spines; G, pereopod-6 carpus, enlargement; H, pereopod-6 propodus, enlargement of obscured setation. Scale bars: 0.1 mm, except G–H 0.05 mm.