Childia aculifera, Nilsson, Karin Sara, Wallberg, Andreas & Jondelius, Ulf, 2011

Nilsson, Karin Sara, Wallberg, Andreas & Jondelius, Ulf, 2011, New species of Acoela from the Mediterranean, the Red Sea, and the South Pacific, Zootaxa 2867, pp. 1-31 : 15-16

Childia aculifera sp.nov.

( Figs. 13 , 14 , 15 )

Type Material: Holotype: SMNH Type-8060. Paratype 1: SMNH Type-8061, Paratype 2: SMNH Type-8062.

Type Locality. Baye des Citrones in New Caledonia, (22° 17' 44" S, 166° 26' 11" E), at 1 m water depth in fine sand. One specimen found in Amadée Island, 15 m water depth in fine sand, (22° 28' 40" S, 166° 28' 22" E).

Other Material examined. Living specimens in squeeze preparations; 4 sets of 4-5 μm serial sagittal sections of paraffin-embedded immature specimen.

Etymology. Name refers to the needle-like inclusions; acicula = small acus (needle); fera is from fero = to carry; latin.

Description. Mature specimens up to 1,5 mm long and ~350 μm wide. Body shape cylindric and elongate, posterior end tapering and anterior end rounded. Body widest at level of the ovaries. Warm yellow to orange pigmentation scattered across body, more intense in middle of body ( Fig. 13 A). Epidermis completely ciliated with 5 μm long cilia. Frontal organ present, cell bodies of frontal organ extend from U10 to U20. Statocyst 7,5 μm in diameter, located 150 μm from anterior end, at U10. Eosinophilic glands numerous, scattered throughout body. Mouth ventrally located in middle of body, at U50.

Body-wall musculature reversed, longitudinal muscles located outside circular muscles.

Paired ventral ovaries ( Fig. 13 C), each lateral band with up to seven oocytes. Ovary extends anterior to level of mouth and posteriorly to level of bursa, U55 to U85. Globular seminal bursa with wall, at level U85. Female gonopore ciliated, positioned on ventral side, at level of seminal bursa, U85.

Testes paired, lateral to ovaries, extending anteriorly to level of ovaries and posteriorly to male copulatory organ, from level U55 to U90. Ventral male gonopore posteriorly at level U95. Opens immediately to male copulatory organ, with conical stylet-like structure, composed of tightly packed sclerotized needles ( Fig. 13 EF). Individual needles of copulatory structure radiating at the proximal end of the stylet. In pressed live specimens one can detect about 17 needles, up to 50 μm long. Needles weakly stained by eosin. Stylet canal large and filled with sperm, discernible in sections. Seminal vesicle surrounding stylet-like structure.

Long and thin needle-like inclusions present, 28-30 μm long and 2 μm wide, reflective and shiny in transmitted and reflected light ( Fig. 13 BD). Inclusions scattered across body, but missing in anterior part of body, extending from U15 to U100. Inclusions visible with dissecting microscope in living specimens.

Figures

FIGURE 13. Childia aculifera sp. nov. A – E photomicrographs of living specimens. A. Dorsal view of whole specimen. Scale bar: 250 μm. B. View of posterior part of body. Scale bar: 100 μm. C. View of posterior end. Scale bar: 75 μm. D. Inclusions (arrowhead). Scale bar: 30 μm. E. View of posterior part of body. Scale bar: 40 μm. F. Photomicrograph of sagittal histological sections stained with hematoxylin-eosin. Scale bar: 30 μm.

FIGURE 14. Childia aculifera sp. nov. Reconstructions show arrangement of organs. A. Dorsal reconstruction of whole living animal. B. Sagittal reconstruction of the whole animal. Scale bar: 220 μm.

FIGURE 15. Detail from the majority rule consensus tree summarizing the result of the Bayesian analysis of the combined 18 S rDNA, 28 S rDNA and COI dataset with the GTR + G substitution model after 10 million generations sampled every 1000 generations after a burnin of 5 million generations. C. aculifera is placed as the sister to all other Childia species. Childia curinii is placed as the sister species of the two cryptic species identified as C. submaculatum.