EPIALTINAE MacLeay, 1838

Colavite, Jessica, Santana, William & Pohle, Gerhard, 2014, Larval development of the spider crab Menaethius monoceros (Latreille, 1825), (Crustacea: Decapoda: Brachyura: Epialtidae), Journal of Natural History 48 (37 - 38), pp. 2273-2292 : 2275-2282

publication ID	https://doi.org/10.1080/00222933.2014.925596
persistent identifier	https://treatment.plazi.org/id/03FBE76C-0E2D-2177-FE00-2677A925FB18
treatment provided by	Felipe (2021-08-13 00:16:43, last updated by Plazi 2023-11-03 23:12:20)
scientific name	EPIALTINAE MacLeay, 1838
status

Treatment

Subfamily EPIALTINAE MacLeay, 1838 View in CoL

Menaethius monoceros Latreille, 1825 View in CoL

First zoea ( Figure 1 View Figure 1 )

Carapace ( Figure 1A View Figure 1 ). Without dorsal and lateral spines, rostral spine greatly diminished. Ventral margin with densely plumose ‘anterior seta’ ( Clark et al. 1998) posterior to scaphognathite notch, followed by 2–4 smaller plumose setae; carapace otherwise without setae. Eyes sessile. Frontal area bearing a dorsal organ (sensu Martin and Laverack 1992; Lerosey-Aubrill and Meyer 2013).

Antennule ( Figure 1B View Figure 1 ). Unsegmented, smooth, conical. Terminally bearing 2 long, 2 shorter aesthetascs, and 1–2 short simple setae.

Antenna ( Figure 1C View Figure 1 ). Biramous, protopod long and pointed, bearing 2 rows of sharp spinules; endopod bud present; one-segmented exopod slightly longer than protopod with long spinulated distal process; pair of setae about one third from tip, one serrulate and one simple.

Mandible ( Figure 1D View Figure 1 ). With medial toothed molar process and enlarged lateral incisor processes; marginal teeth between molar and incisor processes. Palp absent.

Maxillule ( Figure 1E View Figure 1 ). Coxal endite bearing 7 setae, 4 graded plumodenticulate terminally, 3 plumodenticulate subterminally. Basial endite with 4 terminal plumodenticulate cuspidate setae and 3 subterminal plumodenticulate setae. Two-segmented endopod, proximal segment without seta, distal segment with 5 plumodenticulate setae, 1 subapical and 4 terminal. Exopod seta absent.

Maxilla ( Figure 1F View Figure 1 ). Coxal endite bilobed, proximal lobe with 4–5 setae, 3–4 plumose and 1 plumodenticulate; distal lobe with 3–4 setae, 1–2 plumose and 2 plumodenticulate. Basial endite bilobed, proximal and distal lobes with 5 and 4 plumodenticulate setae, respectively. Microtrichia present on both endites. Unsegmented endopod unilobed, with 5 plumodenticulate setae, 3 apical and 2 subapical; microtrichia on distal margin. Scaphognathite marginally with 9–11 densely plumose setae, including distal process.

Maxilliped I ( Figure 1A, G View Figure 1 ). Coxa with plumodenticulate seta. Basis with 9 plumodenticulate setae arranged 2 + 2 + 2 + 3. Endopod 5-segmented with 3, 2, 1, 2, 4 plumodenticulate setae and an accessory spine on the distal segment. Incompletely bisegmented exopod with 4 terminal plumose natatory setae.

Maxilliped II ( Figure 1A, H View Figure 1 ). Coxa without seta. Basis with 3 plumodenticulate setae. Endopod three-segmented, with 0, 1, 4 plumodenticulate setae, distal segment with 2 subapical, 2 apical setae. Incompletely bisegmented exopod with 4 terminal plumose natatory setae.

Maxilliped III ( Figure 1A View Figure 1 ). Present as a small undifferentiated bud.

Pereiopods ( Figure 1A View Figure 1 ). Present as small buds, chela indistinct.

Pleon ( Figure 1A, I View Figure 1 ). Five somites. Somite 1 with pair of middorsal long simple setae, somites 2–5 each with pair of shorter posteromedial simple setae. Posterolaterally, somite 2 with blunt process, somites 3–5 with short lateral projections; somite 2 with pair of dorsolateral processes. Pleopod buds rudimentary.

Telson ( Figure 1I View Figure 1 ). Bifurcated, without median notch, three pairs of plumodenticulate setae on inner margin; each furcal shaft proximally bearing lateral spine, furcal shafts and spines covered in rows of spinules to just below tips.

Second zoea ( Figure 2 View Figure 2 )

Carapace ( Figure 2A View Figure 2 ). Eyes mobile. Ventral margin with densely plumose anterior seta followed by 3–4 plumose setae; pair of small plumodenticulate setae dorsally.

Antennule ( Figure 2B View Figure 2 ). With 6–7 long aesthetascs and a short simple seta, endopod bud present.

Antenna ( Figure 2C View Figure 2 ). Endopod bud enlarged to just beyond middle of protopodite.

Mandible ( Figure 2D View Figure 2 ). Palp bud present.

Maxillule ( Figure 2E View Figure 2 ). Basial endite with 9–10 setae, additional graded plumodenticulate seta terminally, additional plumodenticulate setae subterminally; optional very small plumodenticulate seta on proximal margin; exopod pappose seta present.

Maxilla ( Figure 2F View Figure 2 ). Basial endite with 5 plumodenticulate setae on proximal lobe and distal lobe; Scaphognathite with 19–21 marginal plumose setae.

Maxilliped I ( Figure 2A View Figure 2 ). Exopod with 6 plumose natatory setae.

Maxilliped II ( Figure 2A View Figure 2 ). Exopod with 6 plumose natatory setae.

Maxilliped III ( Figure 2A,G View Figure 2 ). Exo-, endo- and epipod buds distinct.

Pereiopods ( Figures 2A,H View Figure 2 ). Longer, chela apparent.

Pleon ( Figures 2A, I View Figure 2 ). Additional sixth somite. Posterolaterally, somites 1 and 6 with blunt processes, somites 2–5 with enlarged lateral projections; somite 1 with three middorsal long simple setae. Pair of unsegmented biramous pleopods on somites 2–5, endopods very small.

Megalopa ( Figures 3 View Figure 3 and 4 View Figure 4 )

Carapace ( Figures 3A, B View Figure 3 ). Longer than wide, subrectangular; rostral spine very short, ventrally deflected; hepatic region projected, forming 1 knob-like lateral expansion, gastric region well developed, divided in 2 regions, protogastric and metagastric; protogastric region swollen bearing the dorsal organ medially; branchial, cardiac and intestinal regions well defined, inflated. Posterior margin with 10 simple setae, surface covered mostly with simple setae as shown.

Antennule ( Figure 3C View Figure 3 ). Three-segmented peduncle, proximal segment without setae, middle and distal segments with one simple seta each; endopod unsegmented with 1 subterminal and 2 terminal long simple setae. Four-segmented exopod, first segment without seta, second segment with 6 aesthetascs and simple seta, third segment with 4 aesthetascs, distal segment with aesthetasc-like subapical seta.

Antenna ( Figure 3D View Figure 3 ). Segments 1–7, progressing proximally to distally, each with 1, 2, 3, 0, 0, 4, 4 simple setae, respectively. Basal segment with distinct exopod process.

Mandibles ( Figure 3E View Figure 3 ). Asymmetrical, scoop-shaped process with cutting edge and small acute tooth; two-segmented palp bearing 5 plumodenticulate setae on the distal segment.

Maxillule ( Figure 3F View Figure 3 ). Coxal endite with 5 graded plumodenticulate setae apically, 3 plumodenticulate setae, and a plumose seta subterminally. Basial endite with 17 setae, 7 plumodenticulate cuspidate terminally, 8 plumodenticulate subterminally, 2 plumose setae on proximal margin. Epipod plumodenticulate seta present; two-segmented endopod lacking outgrowths.

Maxilla ( Figure 3G View Figure 3 ). Coxal endite bilobed; proximal lobe with 6 setae, 5 plumose setae and 1 plumodenticulate seta; distal lobe bearing 2 plumose setae. Basial endite with 5 and 6 plumodenticulate setae on proximal and distal lobes, respectively. Endopod reduced, with microtrichia on distal margin, without setae. Scaphognathite with 28–31 marginal plumose setae; blade with 3 simple setae.

Maxilliped I ( Figure 4A View Figure 4 ). Coxa with 6 plumodenticulate setae, basis bearing 10–11 plumodenticulate setae; endopod without setae; exopod with pappose seta distally on proximal segment, 4 plumose setae on distal segment; epipod with 4 plumodenticulate setae, 1 proximal, 3 distal.

Maxilliped II ( Figure 4B View Figure 4 ). Coxa and basis not clearly differentiated; four endopod segments proximally to distally with 0, 1, 3 and 6 plumodenticulate setae, respectively; exopod with naked proximal segment and 4 plumose setae on distal segment; epipod not present on examined specimens.

Maxilliped III ( Figure 4C View Figure 4 ). Coxa with 1 + 4 plumodenticulate setae, basis fused to ischium, endopod proximally to distally with 10–11 + 1, 5–6 + 3, 4 + 2, 4 and 4 plumodenticulate setae; ischium with protuberances indicative of crista dentata; bisegmented exopod, naked proximal segment, distal segment with 4 plumose setae apically; epipod with short plumodenticulate seta proximally, 3 long plumodenticulate setae distally.

Pereiopods ( Figure 4D View Figure 4 ). Cheliped with mostly simple setae; pereiopods 2–5 mostly with simple setae; basischial segments without spines; coxa of pereiopod 2 with prominent spine; dactyls of pereiopods 2–5 with rows of spinules as shown; 1–2 serrulate setae near tip of dactyls on ventral margin.

Sternum ( Figure 4E View Figure 4 ). Segments 1–3 completely fused into single plate with bellshaped anterior margin, without setae; segment 4 with 2 pairs of simple setae; segment 5 with 1 pair of simple setae; subsequent segments without setae.

Pleon ( Figure 4F View Figure 4 ). Somites 1–5 proximally to distally with 4, 8, 6, 6, 6 simple setae dorsally and laterally, sixth somite with 2 simple setae.

Pleopods ( Figure 4G View Figure 4 ). Four pairs of pleopods, exopods each with 11, 11, 10, 8 plumose natatory setae, respectively; endopod with 2 cincinnuli each. Uropod reduced, segments fused, with 5 plumose setae distally, endopod absent.

Telson ( Figure 4F View Figure 4 ). Rounded posteriorly, bearing a pair of simple dorsal setae.

References

Clark PF, Calazans DK, Pohle G. 1998. Accuracy and standardization of brachyuran larval descriptions. Invertebr Repr Dev. 33: 127 - 144.

Latreille PA. 1825 - 1828. Histoire Naturelle. Entomologie, ou Histoire naturelle des Crustaces, des Arachnides et des Insectes. Encyclopedie Methodique. Vol. 10. Paris: Agasse Imprimeur-Libraire; p. 832.

Lerosey-Aubrill R, Meyer R. 2013. The sensory dorsal organs of crustaceans. Biol Rev Camb Philos Soc. 88: 406 - 426.

MacLeay WS. 1838. On the brachyurous decapod Crustacea brought from the Cape by Dr. Smith. In: Smith A, editor. Illustrations of the Annulosa of South Africa; being a portion of the objects of natural history chiefly collected during an expedition into the interior of South Africa, under the direction of Dr. Andrew Smith, in the years 1834, 1835, and 1836; fitted out by ' The Cape of Good Hope Association for Exploring Central Africa'. London: Smith, Elder, and Co; p. 53 - 71, 2 plates.

Martin JW, Laverack MS. 1992. On the distribution of the crustacean dorsal organ. Acta Zoologica. 73: 357 - 368.

Figures

Figure 1. First zoea of Menaethius monoceros (Latreille, 1825). (A) lateral view and magnified ventrolateral carapace margin (maxilliped natatory setae shown truncated); (B) antennule; (C) antenna (endopod bud stippled); (D) right mandible; (E) maxillule, with enlargement of coxal and basial endites; (F) maxilla, with enlargement of coxal and basial endites; (G) maxilliped I, with enlargement of distal endopod segment; (H) maxilliped II; (I) dorsal view of abdomen and telson. Scale bars = 0.1 mm.

Figure 2. Second zoea of Menaethius monoceros (Latreille, 1825). (A) lateral view and magnified ventrolateral carapace margin (maxilliped natatory setae shown truncated); (B) antennule; (C) antenna; (D) right mandible; (E) maxillule, with enlargement of coxal and basial endites; (F) maxilla, with enlargement of coxal and basial endites; (G) chela and pereopods; (H) dorsal view of abdomen and telson. Scale bars = 0.1 mm.

Figure 3. Megalopa of Menaethius monoceros (Latreille, 1825). (A) lateral view; (B) dorsal view; (C) antennule, with aesthetascs shown truncated; (D) antenna; (E), left mandible, with enlargement of distal palp segment; (F) maxillule; (G) maxilla. Scale bars = 0.1 mm.

Figure 4. Megalopa of Menaethius monoceros (Latreille, 1825). (A) maxilliped I; (B) maxilliped II, with enlargement of distal endopod segments; (C) maxilliped III; (D) pleopods 1–4 and uropod (natatory setae shown truncated, without setules), distal setae shown truncated; (E) cheliped and pereiopods; (F) sternum; (G) dorsal view of abdomen and telson. Scale bars = 0.1 mm.