Chaetonotus (Zonochaeta) cestacanthus Balsamo, 1990

Kolicka, Małgorzata, 2019, Gastrotricha - not only in sediments: new epiphytic species of Chaetonotida from the Jubilee Greenhouse of the Botanical Garden in Kraków, European Journal of Taxonomy 511, pp. 1-100 : 47-51

Chaetonotus (Zonochaeta) cestacanthus Balsamo, 1990

Figs 33–34 ; Table 6

Chaetonotus (Zonochaeta) cestacanthus Balsamo, 1990: 168 , fig. 4.

Locus typicus

Italy.

Material examined POLAND • 3 adults, 1 juvenile; Kraków, Botanical Garden, Jubilee Greenhouse, sites 1–2 ; 50°03'38" N,

19°57'30" E; 15 Nov. 2013 and 17 Apr. 2014; M. Kolicka leg.; NHC-GCZC-24-1-10 (photomicrographs, also in the author’s collection).

Distribution

Chaetonotus (Z.) cestacanthus Balsamo, 1990 was originally described from Italian lakes, namely Lake Chiusi and Lake Bolsena ( Balsamo 1990), and next recorded from the volcanic Lake Nemi, also in Italy ( Balsamo & Fregni 1995). It has not previously been listed outside of this country.

Remarks

The original description of C. (Z.) cestacanthus is very detailed ( Balsamo 1990) and specimens found in the Jubilee Greenhouse in Kraków correspond well with it. However, the present specimens differ from the original data in being slightly larger ( Table 6 ) and in having three pairs of dorsal sensory bristles instead of two (the additional pair arising on the head, near the dorsal cephalion edge); the first scales of the dorsal longitudinal rows, located near the cephalion and epipleurae, are more elongated and have longer spines than the remaining head scales in comparison to the original description and figures ( Figs 33–34 ); the ventrolateral and ventral scales are similar to the dorsal ones ( Fig. 33B ), and dorsolaterally on the furcal appendages they have one pair of double-keeled scales, rounded in shape, with shallow posterior notches ( Fig. 34B ).

Chaetonotus (Zonochaeta) cestacanthus has previously been recorded only as an element of benthic assemblages in sandy sediments, as well as in sediments rich in detritus, at a station with rich vegetation ( Balsamo 1990; Balsamo & Fregni 1995). There have been no reports of this taxon being found in epiphytic or other periphyton communities, although their presence in samples collected near rich aquatic vegetation may suggest that C. (Z.) cestacanthus could also survive in this habitat type.

Figures

Fig. 33. Chaetonotus (Zonochaeta) cestacanthus Balsamo, 1990. Adult specimen. Bright field microphotographs. A. Scales and spines, dorsal view. B. Scales and spines, ventral view.

Fig. 34. Chaetonotus (Zonochaeta) cestacanthus Balsamo, 1990. Adult specimen. A. Habitus, phase contrast microphotograph. B. Posterior trunk region, furca base and furcal appendages, dorsal view, phase contrast microphotograph. C. Posterior trunk region, furca base and furcal appendages, dorsal view, bright field microphotograph.

Tables

Table 6 (continued on next page). Main morphometric characters of Chaetonotus (Zonochaeta) cestacanthus Balsamo, 1990. N = number of specimens analysed; NA = data not available; Range = the smallest and the largest structure found among all specimens measured. All measurements in micrometers (μm).

Characters	According to Balsamo (1990)	N	Range of adult specimens	Juvenile specimen
Body length	64.50–80.00	3	87.19–89.11	70.12
Furca length	8.50–11.00	3	14.91–15.77	15.05
Adhesive tube length	NA	3	7.50–8.13	8.06
Number of scales in central longitudinal row	13–14	3	14	13
Total number of longitudinal alternating rows of scales	15	3	15	13
Length of cephalic cilia (anterior tuft)	(8.50–10.50)– (18.50–20.0)	3	(7.85–8.11)–(20.89–22.46)	7.34–18.16
Length of cephalic cilia (posterior tuft)	8.50–10.50	3	(8.24–9.55)–(11.73–16.54)	8.15–11.37
Head scales length × width	3.50–4.20 × 2.50–3.20	3	(2.98–3.19)–(4.67–5.02) × (2.18–2.34)–(3.63–3.83)	2.89–4.22 × 2.09–3.32
Neck scales length × width	3.00 × 2.80	3	(2.56–2.91)–(4.19–4.67) × (2.77–3.19)–(4.10–4.31)	2.34–3.83 × 2.67–3.86
Trunk scales length × width	6.50–8.70 × 5.30–6.50	3	(3.89–4.05)–(9.46–9.59) × (3.26–3.91)–(7.20–7.85)	3.68–5.94 × 3.10–4.72
Scales with long dorsal spines length × width	3.70–4.60 × 3.20–3.70	3	(4.24–4.78)–(4.69–4.95) × (2.89–3.30)–(3.19–3.53)	4.19–4.81 × 3.22–3.46
Median and dorsolateral scales with long spines on posterior trunk region length × width	6.00 × 4.00–6.00	3	(5.68–6.70)–(5.86–7.19) × (5.22–5.88)–(5.42–6.47)	5.03–5.72 × 4.41–4.76
Double keeled scales on furcal appendages length × width	NA	3	4.36–4.93 × 4.04–4.51	3.85 × 3.52
Head dorsal spines length	1.30–2.30	3	(0.39–0.51)–(3.17–4.61)	0.34–3.97
Head ventral spines length	2.00–7.80	3	(3.02–3.81)–(6.14–6.54)	2.84–5.79
Neck dorsal spines length	1.30–2.30	3	(0.31–0.37)–(2.66–2.74)	0.27–2.30
Neck ventral spines length	2.00–7.80	3	(6.23–6.82)–(7.28–7.79)	6.08–7.14
Trunk dorsal spines length	1.30–2.30	3	(2.34–2.49)–(2.81–2.92)	2.12–2.92
Trunk ventral spines length	2.00–7.80	3	(7.47–8.06)–(9.16–10.12)	7.36–9.69
Long dorsal spines length	13.50–17.80	3	19.69–20.61	18.28
Median spine on posterior trunk region length	9.30–11.00	3	8.20–9.66	7.8
Dorsolateral spines on posterior trunk region length	7.20–8.70	3	7.18–7.69	6.61
Head dorsal sensory bristles length	NA	3	9.47–11.21	10.29
Neck dorsal sensory bristles length	8.70–10.20	3	12.95–14.29	12.7
Posterior dorsal sensory bristles length	8.70–10.20	3	14.23–15.62	13.94
Number of scales in central longitudinal row on ventral interciliary field	25–26	3	25–26	23
Total number of longitudinal alternating rows of scales on ventral interciliary field	2	3	2	2