Rayllianassa aurora, Poore, 2023

Poore, Gary C. B., 2023, New records, one new genus and 21 new species of Callianassidae (Crustacea, Axiidea) from the Indo-West Pacific, Memoirs of Museum Victoria 82, pp. 167-255 : 227-230

Rayllianassa aurora sp. nov.

http://zoobank.org/urn:lsid:zoobank.org:act:31B5E2A2-ED53-

4D67-95DD-A1EB669EEFA1

Figures 37a , 40 , 41

Callianassa amboinensis .—Hoyoux, 2006: 33.— Samadi et al., 2010: 462.

Rayllianassa cf. amboinensis .— Robles et al., 2020: figs 1, 3, 6 (part from Philippines).

Material examined. Holotype. Philippines. Luzon, Lamon Bay , 14° 27' N, 121° 47' E, 300 m (AURORA 2007 stn CP2720), MNHN IU-2016- 8126 (ovigerous female, 4.4 mm) . Paratypes, collected with holotype. MNHN IU-2013-7135 (16 females, 1.8–4.9 mm), NMV J71762 (3 ovigerous females, 4.9 mm); MNHN IU-2013-7136 (ovigerous female, 4.0 mm), MNHN IU-2016-8124 *# (ovigerous female, 5.1 mm); MNHN IU-2016-8125 # (ovigerous female, 4.4 mm). Philippines. Luzon, Lamon Bay , 14° 29' N, 121° 43' E, 311–361 m (AURORA 2007 stn CP2717), MNHN IU-2013-7139 (9 females, 1.6–3.4 mm) . Other material. Papua New Guinea, Salomon Is, Tetepare, 08° 47' S, 157° 31' E, 94–133 m ( SALOMON 2 stn CP2295), MNHN IU-2016- 8143 (female, 5.4 mm), MNHN IU-2017-1353 (ovigerous female, 3.1 mm), MNHN IU-2017-1358 (female, 5.4 mm) . Other material examined by P.C. Dworschak. Philippines, Luzon, Lamon Bay, MNHN AURORA 2007 stations: 14° 29' N, 121° 48' E, 216–220 m (stn CP2718), NHMW 26465 (ovigerous female, 5.3 mm) ; 14° 26' N, 121° 48' E, 160– 155 m (stn CP2719), NHMW 26467 (7 females) ; 14° 27' N, 121° 47' E, 300 m (stn CP2720), NHMW 26466 (ovigerous female) , NMCR 50819 (female); 14° 23' N, 121° 50' E, 156– 147 m (stn CC2723 ), NMCR 50820 (female), NMCR 50821 (ovigerous female); Baler Bay , 15° 54.2' N, 121° 54.2' E, 100 m (stn CP2760), NMCR 50808 (ovigerous female), NMCR 50822 (ovigerous female), NMCR 50823 (ovigerous female).

Diagnosis. Antennular peduncle little shorter than antennal peduncle. Major cheliped merus with tooth or small teeth along lower margin; carpus oval in cross-section, margins weakly carinate; palm upper margin with obsolete carina, with tubercles and ridges on distal mesial and lateral margins at the base of fingers; dactylus with blade along cutting edge, apex simple. Pereopod 3 propodus oval, not wider proximally. Uropodal exopod widest near midpoint, 1.8 times as long as wide.

Description of holotype. Hermaphrodite. Rostrum obsolete, situated below level of dorsal carapace. Carapace dorsally convex in lateral view, as long as pleomeres 1–2 combined; orbital margin almost transverse, with pair of uncalcified areas laterally; anterolateral angle blunt; subanterolateral margin almost horizontal; anterior margin of branchiostegite convex; cervical groove deeply incised, across 0.8 length of carapace, reaching linea thalassinica. Pleomere 1 tergite with shallow transverse groove. Pleomere 2 twice as long as pleomere 1. Pleomere 6 about as long as wide.

Eyestalk 1.2 times as long as wide, with dorsal face depressed anteriorly, with sharp ventrolateral margin, anterolateral margin oblique, anteromedial angle angular in dorsal view, displaced laterally, reaching distal margin of antennular peduncle article 1. Cornea densely pigmented, occupying anterolateral margin of eyestalk.

Antennular peduncle little shorter than antennal peduncle; article 1 visible in dorsal view; article 3 1.2 times as long as articles 1 and 2 combined; article 2 with dense longitudinal ventral row of long setae; article 3 with well-spaced ventral setae. Antennal peduncle article 5 about as long as article 4; scaphocerite triangular.

Maxilliped 3 ischium dilating distally, 1.2 times as long as wide, crista dentata consisting of about 20 small, well-spaced irregular teeth; merus 0.7 times as long as ischium measured along outer margin, about 1.6 times as wide as long, as wide as ischium, with mesiodistal margin produced as weak lobe beyond base of carpus; carpus little shorter than merus outer margin; propodus ovoid-tapering, 1.5 times as long as wide; dactylus ovoid, as long as propodus.

Pereopods 1 (chelipeds) unequal, dissimilar. Major cheliped massive, carpus-palm upper margin 1.2 carapace length. Ischium expanding distally, upper margin concave, unarmed; lower margin with row of 7 similar small teeth. Merus as long as ischium, 1.5 times as long as wide (tooth excluded), ovate; upper margin convex, unarmed; lower margin with tooth near midpoint, another minor tooth more distal. Carpus 0.65 as long as wide; upper margin rounded; lower margin weakly carinate, with shallow mesial depression parallel to margin. Propodus upper margin 2.1 times as long as carpus; palm almost parallel-sided, 1.2 times as long as wide; upper margin obscurely angled along mesial length; lateral surface smooth, convex; distolateral margin of palm oblique, with tubercle near base of finger; mesial surface convex, distomesial margin oblique, set back from distolateral margin, with prominent oblique crenellate ridge; lower margin carinate, with row of setae extending onto fixed finger; fixed finger 0.5 length of palm, triangular; cutting edge lateral, a crenellate blade. Dactylus as long as fixed finger, hooked distally, with acute tip; upper margin double-ridged, with tufts of long setae; lateral surface with few tufts of long setae along cutting edge; cutting edge with triangular tooth one third along, blade-like over distal half.

Minor cheliped carpus-palm upper margin 0.7 carapace length. Ischium upper margin smooth, lower margin with row of 3 teeth. Merus about as long as ischium; lower margin with obtuse angle at midpoint. Carpus wider distally, 0.8 length of merus, as long as wide, upper and lower margins rounded. Palm swollen, 1.4 times as long as wide; upper margin convex, with obscure mesial angle; lower margin carinate, with row of long setae extending onto fixed finger; distomesial margin with small tubercle at base of fixed finger; distolateral margin with crenellate oblique ridge at base of finger. Fixed finger, 0.7 length of palm, cutting edge lateral, with small irregular tubercles. Dactylus malformed in holotype, tapering, as long as fixed finger in paratypes.

Pereopod 2 merus lower margin slightly sinusoidal, 2.3 times as long as wide; carpus about 1.6 times as long as wide; chela subtriangular; palm about 1.3 times as wide as upper margin; dactylus 1.5 times as long as palm upper margin. Pereopod 3 merus 2.8 times as long as wide; carpus subtriangular, 1.8 times as long as wide; propodus oval, upper margin 1.2 times greatest width, lower margin evenly convex, without proximal heel, marginal setae with 3 clear gaps along distal half, with 1 slender spiniform seta subdistally; dactylus about 0.6 length of propodus upper margin. Pereopod 4 coxa flattened ventrally, distal articles linear. Pereopod 5 chelate.

Pleopod 1 of 2 articles at right angles; ramus about as long as peduncle; setose. Pleopod 2 biramous; endopod slightly shorter than exopod. Pleopods 3–5 biramous, endopod 2.4 times as long as wide; appendix interna slender, rod-like, projecting well beyond mesial margin of endopod.

Uropod endopod and exopod overreaching posterior margin of telson. Endopod oval, widest near midpoint, about twice as long as wide; upper surface with 2 spiniform setae on dorsal rib; anterior margin almost straight; distal margin evenly convex, with fringe of setae; posterior margin setose. Exopod widest near midpoint, 1.8 times as long as wide, exceeding endopod by one quarter its length; anterior margin convex; all margins with numerous slender setae, with about 12 blade-like setae on posterior margin indistinguishably merged with distal margin; dorsal plate apparent on distal margin as row of about 7 stiff setae merging anteriorly with similar setae on anterior margin.

Telson as wide as long, broadest at anterior fifth, narrowing posteriorly to broadly rounded posterolateral corners; posterolateral corners each with 2 spiniform setae; posterior margin medially excavate, with minute median tooth; dorsal surface with few medial setae.

Variation. The rostrum of the types from the Philippines is shorter (figs 40d, 41b) than that of the two specimens from Papua New Guinea (fig. 41p). The armature on the distomesial margin of the propodus of the major cheliped varies from a crenellate ridge to rugose tubercle (cf. figs 40f, 41d, n, q); the distolateral margin appears to be always produced, often with a tubercle uppermost on the distal ridge (figs 40h, 41e, o, r). The uropodal endopod is about twice as wide as long in the holotype (fig. 40e) but is relatively wider in the illustrated paratype (fig. 41c) and the example from Papua New Guinea (fig. 40s); all appear to have two spiniform setae along the rib. The pereopod 5 propodus of the illustrated paratype has a secondary bunch of setae on a secondary “thumb” (fig. 41h) .

Etymology. From AURORA, the name of the MNHN cruise during which this material was collected, so named after the Aurora Memorial National Park on the eastern coast of Luzon, the Philippines (noun in apposition).

Distribution. Western and Eastern Coral Triangle ( Philippines, Papua New Guinea); 94– 361 m.

Remarks. Rayllianassa aurora differs from R. amboinensis in: (1) having an oval propodus on pereopod 3 (not wider proximally as in R. amboinensis ); (2) the peduncle of the antennule being shorter than that of the antenna (the antennular peduncle is longer in R. amboinensis ); (3) a narrower uropodal exopod; and (4) tubercles and ridges on the distal mesial and lateral margins of the palm of the chelipeds at the base of the fingers. Robles et al. (2020) recorded one of the paratypes as Rayllianassa cf. amboinensis .

The major cheliped of R. aurora is similar to that of R. bangensis Sakai, 2005 , also from the Philippines. Sakai (2005) figured the antennal peduncle as longer than the antennular peduncle (as in Rudisullianassa ) and the telson much longer than in R. aurora .

Much of the material recorded from the Philippines at the AURORA 2007 stations was associated with wood.

Figures

Figure 37. Rayllianassa spp. a, R. aurora sp. nov., Philippines, MNHN IU-2016-8126, ovigerous female, 4.4 mm; b, Rayllianassa sp. Philippines, NHMW 25915, ovigerous female, 4.3 mm. (colour photographs by T.-Y. Chan).

Figure 40. Rayllianassa aurora sp. nov. Philippines. MNHN IU-2016-8126, holotype ovigerous female, 4.4 mm: a, eyestalks, carapace, pleon, uropods, telson (dorsal); b, eyestalk, carapace, pleomeres 1, 2 (lateral); c, d, eyestalk, antennular, antennal peduncles, anterior carapace (lateral, dorsal); e, pleomere 6, right uropod, telson; f, major cheliped (left, mesial); g, major cheliped, carpus–dactylus (upper view); h, major cheliped distal palm, fingers (lateral); i, major cheliped (cross-section, upper topmost, mesial left); j, minor cheliped (right, mesial); k, minor cheliped distal palm, fingers (lateral); l, maxilliped 3; m, n, pereopods 2, 3; o, pereopod 3 propodus, dactylus; p, pereopod 4. Scale bars = 1 mm.

Figure 41. Rayllianassa aurora sp. nov. Philippines. MNHN IU-2016-8125, paratype ovigerous female, 4.4 mm: a, b, eyestalk, antennular, antennal peduncles, anterior carapace (lateral, dorsal); c, pleomere 6, left uropod, telson; d, major cheliped (left, mesial); e, major cheliped distal palm, fingers (lateral); f, minor cheliped (right, mesial); g, minor cheliped distal palm, fingers (lateral); h, right pereopod 5 propodus, dactylus (atypical); i, left pereopod 5 propodus, dactylus; j, maxilliped 3. MNHN IU-2016-8126, holotype ovigerous female, 4.4 mm: k–m, pleopods 1–3. MNHN IU-2016-8124, paratype ovigerous female, 5.1 mm: n, major cheliped palm, fingers (left, mesial); o, major cheliped distal palm, fingers (lateral). Papua New Guinea, MNHN IU-2017-1358, ovigerous female, 5.4 mm: p, anterior carapace, eyestalks, antennular, antennal peduncles (dorsal); q, major cheliped palm, fingers (left, mesial); r, major cheliped distal palm, fingers (lateral). MNHN IU-2016-8143, ovigerous female, 5.4 mm: s, left uropod, telson. Scale bars = 1 mm.