Acallocheirus, Bird & Bamber, 2013
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publication ID |
https://doi.org/ 10.11646/zootaxa.3676.1.1 |
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publication LSID |
lsid:zoobank.org:pub:7AB2D8F5-62F2-46D1-BDE4-BF91D6513797 |
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persistent identifier |
https://treatment.plazi.org/id/063873AB-DD41-4D37-98E3-A54D4B88B42A |
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taxon LSID |
lsid:zoobank.org:act:063873AB-DD41-4D37-98E3-A54D4B88B42A |
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treatment provided by |
Felipe |
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scientific name |
Acallocheirus |
| status |
gen. nov. |
Acallocheirus View in CoL gen. nov.
Diagnosis. Female: Body slender. Cephalothorax 1.5 times as long as broad, carapace not divided into plates [‘entire’]. Pereonite-1 trapezoidal [narrower posteriorly]. Pleon longer than broad; pleonites 1–4 epimera with large articulated pappose seta. Pleotelson not plate-like. Antennule four-articled, without distinct caplike terminal segment; PSS (plumose [or pappose] sensory setae) of article-2 short [cf. Pseudobathytanais ] Antenna article-2 with thorn-like inferior spine (or apophysis with terminal seta); article-3 with superior spine; articles 2–4 without longitudinal ridge [c.f. Pseudobathytanais ]. Mandible body smooth. Maxilliped endite tubercles small, rounded; palp article-2 without modified medial seta. Cheliped palm [= manus], without distolateral (sinuate) spine near articulation with dactylus, medial comb with two spines; fixed finger inferior margin with two setae; dactylus incisive margin peg-like spines broad. Pereopods 1–3 basis naked [uncertain]. Pereopods 2–3 carpus inferodistal pair of spines longer than broad, equal in length. Pereopods 4–6 ischium with one seta; carpus with weak inferior spinulation. Uropod with exopod, as long as peduncle; endopod twice as long as peduncle. Male unknown.
Etymology. From Greek akalles, ‘ugly’ and cheirus, ‘hand’, alluding to the cheliped.
Gender. Male.
Type species. Acallocheirus echmanomus View in CoL sp. nov., by monotypy.
Distribution. New Zealand.
Remarks. This genus differs from Paratanais in its more slender habitus, especially the cephalothorax and pleon, the small maxilliped endite tubercles (but see Aparatanais gen. nov.), and the lack of a cheliped palm spine near the dactylus. The first ‘character’ is somewhat subjective and prone to variations due to relaxation/contraction effects in Paratanais and allied genera. Further possible distinctions are the single ischial seta of pereopods 4–6 and the form of the inferodistal carpal spines of pereopods 2–3, which in Acallocheirus gen. nov. are similar-sized but which are unequal in most Paratanais species , although the new genus Penteparatanais [described below] appears to share this. Acallocheirus is more similar in habitus and general morphology to Pseudobathytanais shtockmani Kudinova-Pasternak, 1990 but the antennule lacks the long PSS on antennule article-2 and a cap-like terminal segment, it lacks the longitudinal ridge on antennal articles 2–4, the mandible body is smooth, and pereopods 2–3 have two inferodistal spines on the carpus.
Acallocheirus echmanomus sp. nov.
Figures 1–3 View FIGURE 1 View FIGURE 2 View FIGURE 3 , 36F View FIGURE 36
Material examined. Holotype: non-ovigerous [non-ov.] ♀, CR.23395, partly dissected on microslide CR.23395/1, Stn GJB/4-12, Carpophyllum plumosum var. capillifolium (A. Richard) J. Agardh holdfasts, LWS, outer reef,
Paratype: non-ov. ♀, anterior fragment, CR.23396, partly dissected on microslides CR.23396/1 and CR.23396/2 Stn GJB/4-12; details as for holotype.
Etymology. From Greek, echma, ‘holdfast’ and nomus, ‘place or condition for living’; alludes to the habitat.
Description. Non-ovigerous female: Habitus ( Fig. 1A View FIGURE 1 ) eight times longer than broad [ltb]; length 2.0 mm. Cephalothorax ( Fig. 1D View FIGURE 1 ) longer than pereonites 1–2 combined; eyelobes well-developed, optical pigment extending beyond lobes. Pereon with pereonites 2–6 with slightly convex lateral margins; pereonites 1–6 0.5, 0.7, 0.7, 0.9, 0.9 and 0.7 times ltb respectively. Pleon 1.5 times ltb, shorter than pereonites 5–6 combined, slightly narrower than pereon and pleotelson. Pleotelson, as long as pleonites 4–5; setation as figured.
Antennule ( Fig. 1B View FIGURE 1 ) 0.8 times as long as cephalothorax; article-1half total length, 2.4 times ltb; article-4 as long as articles 2–3 combined; setation similar to that of NZ Paratanais . Antenna ( Fig. 1C View FIGURE 1 ) article-2 twice as long as article-3, with superodistal seta and mid-inferior thorn-like apophysis; article-3 with acute superodistal spine; article-4 twice as long as article-3, with simple seta and two or three PSS; article-5 with distal seta; article-6 very short, with one short, and three long distal seta (one is either compound or with rudimentary pectination).
Labrum ( Fig. 2A View FIGURE 2 ) relatively small, rounded distally, setulate. Mandible ( Fig. 2B–C View FIGURE 2 ) molars broad, nodulose with few ridges, left molar cleft; lacinia mobilis broad, crenulate; right incisor weakly bifid, with superior crenulations. Labium ( Fig. 2D View FIGURE 2 ) typical [of family]. Maxillule ( Fig. 2E–F View FIGURE 2 ) endite with eight terminal spines, distally setulate; palp with two setae. Maxilla ( Fig. 2G View FIGURE 2 ) subovate. Maxilliped ( Fig. 2H–J View FIGURE 2 ) basis seta not reaching endite distal margin; palp article-2 with lateral seta, medial margin with slender smooth setae and two serrulate setae; article-3 with four setae (three serrulate), article-4 with proximal setules, superior seta and five terminal serrulate setae. Epignath not observed.
Cheliped ( Figs 1D View FIGURE 1 , 2K–L View FIGURE 2 ) coxal sclerite with short posterior extension; basis overlapped by pereopod-1, 1.3 times ltb, with superolateral seta; carpus slightly longer than basis, 1.5 times ltb, with two inferior setae unequal; propodus 1.3 times as long as carpus, 2.1 times ltb, inferior and superior margins parallel, palm almost twice as long as fixed finger, medial comb near superior margin, spines unequal; fixed finger with prominent raised margin and distal lamellate apophysis (‘tooth’), orange-brown; dactylus stout, with two peg-like spines on incisive margin and stout basal seta on medial margin.
Pereopod-1 ( Fig. 3A View FIGURE 3 ) basis longer than ischium–carpus combined, five times ltb; merus 2.7 times ltb, naked; carpus as long as merus, with four distal setae, superodistal largest; propodus 1.5 times as long as carpus, 4.3 times ltb, with two unequal superodistal setae; dactylus and unguis 0.8 times as long as propodus. Pereopod-2 ( Fig. 3B View FIGURE 3 ) basis shorter and stouter than that of pereopod-1, about three times ltb; merus 1.3 times ltb, with inferodistal spine; carpus as long as merus, with small medial superodistal seta, superodistal spine much larger than two inferodistal spines ( Fig 36F View FIGURE 36 ); propodus 1.7 times as long as carpus, with two unequal superodistal seta; dactylus and unguis combined about 0.75 times as long as propodus. Pereopod-3 ( Fig. 3C View FIGURE 3 ) similar to pereopod-2 but slightly shorter; propodus with one superodistal seta.
Pereopod-4 ( Fig. 3D View FIGURE 3 ) basis 2.3 times ltb, with inferior PSS; ischium with seta; merus with two acute, weakly serrate, inferodistal spines; carpus shorter than merus, with weak inferior spinulation, one superodistal seta and four spines, one clearly longer than rest; propodus as long as merus, with two acute inferodistal spines and serrate superodistal spine; dactylus and unguis claw-like, half as long as propodus. Pereopod-5 ( Fig. 3E View FIGURE 3 ) similar to pereopod-4 but basis with two inferior PSS. Pereopod-6 ( Fig. 3F View FIGURE 3 ) similar to pereopods 4–5 but basis naked (?); carpus with three [one probably dislodged on one of the pair of pereopods on same individual) or four spines; propodus without superior PSS, with three superodistal slender serrate spines.
Pleopods (not dissected/figured), well developed, biramous.
Uropod ( Fig. 3G View FIGURE 3 ) shorter than pleotelson; exopod one-segmented, as long as peduncle, slightly shorter than segment-1 of endopod; endopod two-segmented, about twice as long as exopod, segments subequal; setation as figured.
Distribution and ecology. Acallocheirus echmanomus sp. nov. is only known from the type locality among holdfasts of the brown fucoid Carpophyllum plumosum var. capillifolium . Further specimens might be sought in this habitat.
Remarks. The description is based on only two specimens but should suffice to distinguish this species from other paratanaids on the East coast of North Island. The differences from Pseudobathytanais shtokmani were
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