Dactylopodola agadasys Hochberg, 2003

Hummon, William D., 2011, Marine Gastrotricha of the Near East: 1. Fourteen new species of Macrodasyida and a redescription of Dactylopodola agadasys Hochberg, 2003, ZooKeys 94, pp. 1-59 : 9-12

Dactylopodola agadasys Hochberg, 2003 Figure 4

Dactylopodola agadasys Hochberg, 2003: p. 41; Figs. 5-6. -- new species. Hummon et al. (2005: Tab. 1); Hummon (2009: N Am and E Med & Red Sea Databases); Hochberg (2008: p. 103; tab. 2; fig. 2A.)

Redescribed diagnosis:

Adult Lt 390 µm; PhJIn at U32. Head bluntly rounded, but without ocelli, neck constriction extended but slight; trunk slender, with two broad caudal lobes that incise medially to U92, without a peduncle. Glands not seen; protonephridia 3 per side, at U32, U78 and U87; longitudinal muscles are striated. TbA 3 per side (L=6, 8, 11 µm) insert in parallel, protruding obliquely to the rear; TbVL 6 per side, arising in groups of 3/2/1 (L=14, 8, 6 / 17, 7 / 14 µm) at U36-U38 /U46-U49 /U57, all protruding obliquely to the rear, proceding rearward from longer to shorter in each group; TbP 6 per caudal lobe (L=8-10 µm), longest medially on each lobe. Mouth terminal, of medium breadth; buccal cavity goblet-shaped; pharynx width follows the head/neck contours, with inconspicuous basal pores that open well behind the neck constriction; intestine narrows fore to aft, anus ventral at U91. Ventral ciliation: a unified field beneath the head splits into a pair of longitudinal bands, each narrow in breadth, that continues rearward to the level of the anus, and a second pair of longitudinal bands that lie medially from U12 to U34, with a an isolated patch lying medially behind the anus. Probably parthenogenic; male system not seen; ovaries paired in hindgut region, with oocytes on both sides behind the predominant ovum that develops medially forward toward the midgut; caudal and frontal organs not seen.

Redescription:

Adult Lt 322-390 µm; LPh 103-126 µm to PhJIn at U32-U33 (Fig. 4). Body flattened ventrally, vaulted dorsally, comprised of bluntly rounded head that lacks ocelli, neck constriction extended but slight; trunk slender, with two broad caudal lobes that incise medially to U92, without a peduncle. Widths of head /neck /trunk /caudal base are as follows: 30 /24 /36 /25 µm at U10 /U18 /U52 /U88, respectively. Glands absent. Protonephridia 3 per side, each with 2 flagellae, located just before the PhJIn at U32, and in the hindgut region at U78 and U87. Longitudinal muscles are striated, as is characteristic of members of this family.

Adhesive tubes: TbA 3 per side (L 6, 8, 11 µm), inserting in parallel at U05 and protruding obliquely to the rear, proceding rearward from longer to shorter; TbVL 6 per side, arising in groups of 3/2/1 (L 14, 8, 6 /17, 7 /14 µm) at U36-U38 /U46-U49 /U57, all protruding obliquely to the rear, proceding rearward from longer to shorter in each group; TbL per se /TbD /TbV are absent; TbP 6 per caudal lobe (L 8-10 µm), longest medially on each lobe.

Ciliation: Sensory hairs (L 9-18 µm) are abundant on the body, in 5 columns per side - ventrolateral, lateral, 2 dorsolateral and dorsal - of 18-20 per side each from U00 to U93, the tips of each being curled to the rear. Ventral ciliation: a unified field beneath the head splits into a pair of longitudinal bands, each narrow in breadth, that continues rearward to the level of the anus, and a second pair of longitudinal bands lie medially from U12 to U34, with a an isolated patch lying medially behind the anus.

Digestive tract: Mouth terminal, slightly inclined toward the ventral, of medium breadth (8 µm in diameter), goblet-shaped buccal cavity large, with 4 internal sensory hairs (L 2 µm) per side, 3 laterally and 1 posteriorly; pharynx broadest in the buccal region, with breadth following the body contours in the head and neck region, basal pharyngeal pores inconspicuous, opening well behind the level of the neck constriction (U27); foregut broad, midgut narrowing, hindgut broadening a bit before the anus, which occurs ventrally at U91; circular muscules sheath both the pharynx and the intestine, the former more heavily than the latter.

Reproductive tract: Probably parthenogenic; male system not seen; ovaries paired in hindgut region, with oocytes on both sides behind the predominant ovum (77 × 33 µm) which develops medially forward toward the midgut; caudal and frontal organs not seen.

Ecology: Occasional in frequency of occurrence (10-30% of samples), scarce to prevalent in abundance (3% to greater than 30% of a sample, sometimes a co-dominant [cdom]); littoral in fine-medium, medium-well sorted to very poorly sorted clean coralline sand at mean low water to low water spring, 0-15 cm sand depth.

Geographical distribution:

ANW:UNITED STATES:Florida {Bahia Honda SW [video], Crandon Park Inside}. RED:EGYPT: {Sharm el-Arab Inside, Na’ama Bay N, Nabq S [4-videos], Sharm el-Naga [cdom] [video], Ras Nasrani [video]}. CRB:PANAMA: Bocas del Toro {Isla Colón Site 4} IND:AUSTRALIA: Queensland {^Macleay Island W (27°35'S, 153°21'E)}

Remarks

: There are six video records of Dactylopodola agadasys , five from three locations on the Red Sea coast of Egypt, and one from the Atlantic coast of Florida, US (see below). It was listed among the marine gastrotrichs for which videos were available by Hummon, Todaro & Evans 2005. Four of these are available as MPEG 2 (and MPEG 1) from Hummon (2009), all from Nabq S, near Ras Mohamed National Park, on the South Sinai, Egypt: #770 an adult of Lt=389 µm (LPh=121 µm), collected in July 1994, #769 an adult of Lt=369 µm (LPh=120 µm), #772 an adult of Lt=362 µm (LPh=120 µm), and the other #773 an adult of Lt=322 µm (LPh=103 µm).

I found this species in the Red Sea sites while on a Fulbright Senior Research Scholarship during 1994; thus my drawings and videos antedate by seven years its formal description by Hochberg, 2003. He had found it in eastern Australia during 2001, the species now having a much broader biogeographical range than just Austalia or the upper Red Sea. His recent report of the species from Panama ( Hochberg 2008) not only further extends its range, but has implications for an original distribution that would date it back to a time prior to the raising of the Isthmus of Panama some 3 million years ago during the Pliocene. During this past summer (2010), while reviewing videos from Florida collections made during February 1991 by Hummon, Evans & Todaro, I discovered that a species, thought when collected in to be of unknown identity, was in fact Dactylopodola agadasys . It is shown in video #920 (though with unknown length).

The reason for redescribing this species is that Hochberg’s drawing ( Hochberg 2003: Fig. 6) gives an incorrect impression of what the species looks like. By comparison with the photo presented in Hochberg Fig. 5, the drawing as presented in Fig. 6 is not sufficiently thin, and the TbP do not have attached cilia. Other difficulties with the drawing are that the TbA are of increasing length, interior to exterior, and not as shown; moreover the TbVL are grouped in a 3/2/1 sequence, all projecting obliquely to the rear, proceding rearward from longer to shorter in each group, and not occurring as a column of tubes that are equally spaced, though decreasing in size, as shown in Hochberg Fig. 6 (as is confirmed in one of several additional photographs given to me by Hochberg, see under this species in Gastrotrich Figures in Hummon 2009). I cannot speak to the ventral ciliation, as seen by Hochberg, but that which I have drawn in the redescription can be verified in the videos. I also can not speak to the identity of the specimen from Panama, the photo not giving sufficient detail for such an identification, but I give the author of the species the benefit of the doubt in his identification; I have myself seen the species from elsewhere in the Caribbean and made the same identification (as redescribed).

Etymology:

Agadasys (Greek: aga + dasys = meaning 'very hairy’) was named by Hochberg in reference to the numerous tactile cilia that cover the body.

Taxonomic affinities:

Dactylopodola agadasys is presently the thinnest member of the genus, and the only species in the genus that has the following combination of characters: a bluntly rounded head and PhJIn at U33-U32, which also has TbA 3 per side in a parallel series that increases in length medial to lateral; TbVL 6 per side (in clusters of 3, 2 and 1, also parallel and increasing in length medial to lateral); and TbP 6 per side, radiating from broadly rounded lobes, but without TbL per se /TbD /TbV.