Spinicallianassa bilbili, 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 : 240-243

Spinicallianassa bilbili sp. nov.

http://zoobank.org/urn:lsid:zoobank.org:act:66725744-228A-

433E-8432-2C745FA73747

Figure 50

Spinicallianassa PNG-757.— Robles et al., 2020: figs 1, 3, 6.

Material examined. Holotype. Papua New Guinea, Madang Province, S of Madang, near Bil Bil I., 05° 18' S, 145° 46.1' E, 17 m ( PAPUA NIUGINI stn PB29 ), MNHN IU-2013-842 * (ovigerous female, 3.3 mm).

Diagnosis. Telson 1.4 times as wide as long, with dorsal transverse row of long setae, anterolateral lobes angular, lateral margins tapering to angular posterolateral corners; posterior margin truncate. Uropodal endopod 1.7 times as long as wide, with 2 well-spaced spiniform setae on face, with 5 along anterodistal margin; anterior margin without subdistal tooth. Uropodal exopod 1.5 times as long as wide, distal margin convex, dorsal plate comprising 5 spiniform setae, anterior margin with 2 distal spiniform setae. Maxilliped 3 ischium 1.8 times as long as wide; merus rectangular.

Description of holotype. Rostrum spine-like, situated at level of dorsal carapace, almost as long as eyestalk. Carapace dorsally weakly convex in lateral view, as long as pleomeres 1 and 2 combined; orbital margin oblique, convex; anterolateral lobe prominent; subanterolateral margin oblique; anterior margin of branchiostegite evenly convex; cervical groove deeply incised, across 0.9 length of carapace, not reaching linea thalassinica. Pleomere 1 tergite with shallow transverse groove, much narrower anteriorly. Pleomere 2 twice as long as pleomere 1. Pleomere 6 about as long as wide.

Eyestalk about as long as wide, with dorsal face strongly depressed anteriorly (basally about three quarters as high as wide), with sharp ventrolateral margin, lateral margin swollen proximal to cornea, anteromedial angle rounded in dorsal view, overreaching distal margin of antennular peduncle article 1. Cornea densely pigmented, occupying mid-distal of eyestalk.

Antennular peduncle little shorter than antennal peduncle; article 1 scarcely visible in dorsal view; article 3 about 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 0.6 length of article 4; scaphocerite acute.

Maxilliped 3 ischium slightly narrower distally, 1.8 times as long as wide, crista dentata comprising 6 strong curved teeth over proximal half, 9 smaller closer teeth over distal half; merus 0.5 length of ischium measured along outer margin, as wide as long, wider than ischium, with mesiodistal margin oblique, separated from inner margin by distinct rounded corner; carpus as long as merus outer margin; propodus ovoid-tapering, 1.7 times as long as wide; dactylus tapering, shorter than propodus, with scattered setae along upper margin, dense row of short setae along distal lower margin.

Pereopods 1 (chelipeds) unequal, similar. Major cheliped carpus-palm upper margin 0.9 carapace length. Ischium scarcely expanding distally, upper margin almost straight, unarmed; lower margin with row of five similar spines. Merus as long as ischium, 1.7 times as long as wide (tooth excluded), ovate; upper margin convex, unarmed; lower margin with oblique spine near midpoint. Carpus 1.1 times as long as wide; upper margin carinate; lower margin carinate. Propodus upper margin as long as carpus; palm 1.1 times as long as wide; upper margin convex, ridged; lateral surface smooth, convex, with slight concavity at base of finger; distolateral margin of palm slightly convex; mesial surface convex, distomesial margin transverse, set back from distolateral margin; lower margin carinate, with row of setae extending onto fixed finger; fixed finger 0.65 length of palm, triangular; cutting edge lateral, an irregular blade, with minor more medial ridge. Dactylus as long as fixed finger, straight, with acute tip; upper margin ridged, with tufts of long setae; lateral surface with few tufts of long setae along cutting edge; cutting edge with irregular small teeth.

Minor cheliped carpus-palm upper margin 0.8 carapace length. Ischium upper margin smooth, lower margin with row of six spines. Merus about as long as ischium; lower margin with oblique spine at midpoint. Carpus wider distally, about as long as merus, 1.5 times as long as wide, upper and lower margins carinate. Palm as long as wide; upper margin convex, ridged; lower margin carinate, with row of long setae extending onto fixed finger; distomesial margin oblique. Fixed finger 0.7 length of palm, cutting edge lateral, with small irregular teeth, with minor more mesial ridge. Dactylus tapering, curved, unarmed.

Pereopod 2 merus lower margin slightly sinusoidal, 2.5 times as long as wide; carpus about 1.6 times as long as wide; chela subtriangular; palm about 1.7 times as wide as upper margin; dactylus twice as long as palm upper margin. Pereopod 3 unknown. Pereopod 4 coxa flattened ventrally, distal articles linear. Pereopod 5 chelate.

Uropod endopod and exopod overreaching posterior margin of telson. Endopod oval, widest near midpoint, 1.7 times as long as wide; upper surface with 2 spiniform setae on dorsal rib; anterior margin almost straight; distal margin evenly convex, with spiniform setae at anterodistal margin; posterior margin setose. Exopod widest near midpoint, 1.4 times as long as wide, exceeding endopod by one quarter its length; anterior margin straight; all margins with numerous slender setae, with about 15 blade-like setae on posterior margin indistinguishably merged with distal margin; dorsal plate apparent near distal margin as row of about 7 irregularly spaced stiff setae.

Telson 1.4 times as wide as long, broadest at anterior fifth, narrowing posteriorly to broadly rounded posterolateral corners; posterolateral corners each with 2 spiniform setae; posterior margin excavate, with minute median tooth; dorsal surface with few medial setae.

Etymology. Contraction of Bil Bil Island, Papua New Guinea, type locality (noun in apposition).

Distribution. Eastern Coral Triangle ( Papua New Guinea); 17 m.

Remarks. The molecular analysis ( Robles et al., 2020: fig 3) placed this single specimen on a clade sister to seven closely clustering representatives of S. aff. acutirostella , reidentified here as S. spinicauda . Spinicallianassa bilbili differs from S. spinicauda in having a much narrower maxilliped 3 (ischium almost twice as long as wide; about as long as wide in S. spinicauda ), a more triangular rostrum (narrow), rounded distomesial lobes on the eyestalks (acute), the telson with two pairs of distolateral spiniform setae (6–7 pairs of distal marginal spiniform setae), and uropodal endopod with two facial spiniform setae (five spiniform setae in two rows).

Figures

Figure 50. Spinicallianassa bilbili sp. nov. Papua New Guinea. MNHN IU-2013-842, holotype ovigerous female, 3.2 mm: a, eyestalks, carapace, pleon, telson, uropod; b, eyestalks, carapace, pleomeres 1, 2 (lateral); c, thoracic sternite 7, pereopodal coxae 3, 4; d, e, anterior carapace, eyestalks, antennular, antennal peduncles (lateral, dorsal); f, telson, left uropod; g, maxilliped 3 (inner view); h, maxilliped 3 ischium, merus (mesial view); i, major cheliped (left, mesial); j, major cheliped carpus–dactylus (upper); k, major cheliped distal palm, fingers (lateral); l, minor cheliped (right, mesial); m, pereopod 2; n, pereopod 4. Scale bars = 1 mm.