Siphonophora hebetunguis ( Attems, 1951 )

Read, Helen J. & Enghoff, Henrik, 2019, Siphonophoridae from Brazilian Amazonia. Part 2 - Two new treeclimbing species of the genus Siphonophora, including one showing pilosity polymorphism (Diplopoda, Siphonophorida), European Journal of Taxonomy 496, pp. 1-26 : 3-8

Siphonophora hebetunguis ( Attems, 1951)

Figs 1–2 , 9A

Rhinosiphora hebetunguis Attems, 1951: 228 .

Siphonophora hebetunguis – Jeekel 2001: 59.

Diagnosis

Small, pale species with paddle-shaped claws, generally very tuberculate on head, collum, metazonites and coxae. Ventral margin of pleurites almost straight, hind margin with some tubercles. Accessory claw short and arising from lateral side of the claw. Anterior gonopods short and squat, with no spines or other structures at the tip.

Etymology

A noun in apposition from the Latin ‘ hebe ’, meaning ‘blunt’ or ‘dull’ and ‘ unguis ’, meaning ‘claw’ and referring to the shape of the claw. Note that in the original description the spelling hebetungis appears, although the key and figure legends use the spelling hebetunguis . The type series from Vienna is labelled hebetungis. As ‘ unguis ’ means ‘claw’ and the claw shape is referred to in the description, it appears that the use of ‘ hebetungis ’ is probably a lapsus calami and that the spelling hebetunguis can be taken as correct.

Material examined

None of the material is labelled as types, and all the specimens should be considered as syntypes. Two microscope slides, containing the head, first seven body rings, telson, and anterior and posterior gonopods, in combination with a separate body in fluid, constitute a potential lectotype, but we refrain from formally designating it as such. The original description does not list the number of specimens, although both males and females were obviously present.

BRAZIL • 6 ♂♂, 2 ♀♀; ‘Brasilien, Taperinha près Santarem. Coll Zerny’; NHMW 2295 .

Redescription

Mostly made from the non-mounted specimens, as the slides are so cleared that most structures are not easily visible.

MEASUREMENTS. Body length: ♂: 5.2–11.25 mm, ♀: 15–17 mm. Body width: ♂: 0.54–0.64 mm, ♀: 0.88 mm. Number of podous tergites: ♂: 33–50, ♀: 57–62. Number of apodous tergites: ♂: 0, ♀: 1–2.

COLOUR. Pale cream (but may be due to state of preservation).

BODY SHAPE. More or less parallel-sided.

HEAD. In dorsal view showing sinuous or stepped outline laterally between antennal bases and base of rostrum. In lateral view almost flat, with slight demarcation between rostrum and rest of head. Rostrum very slightly downwardly curved. Length of rostrum (to antennal base): ♂: 0.34–0.56 mm, ♀: 0.42– 0.56 mm. Width of head (between antennal sockets): ♂: 0.20 mm, ♀: 0.24–0.26 mm. Abundant setae and tubercles on head. Long setae on gnathochilarium at base of rostrum, some of which reach to rostrum tip.

ANTENNAE. Appearing more or less the same length as rostrum but exact length not analysed, nor length:width ratio of segments. Sensory pits on antennomeres 5 and 6 present but not especially clear or large.

COLLUM. Wide, anterior margin with a gentle curve for anterior margin (not examined in SEM). Posterior margin more or less straight. With abundant setae and tubercles.

TERGITE 2. More than 0.5 × length of collum.

MID- BODY RINGS. When plotted ( Fig. 1 ) this species has a small body size and relatively few rings in the males, but there are not enough females to give a clear picture. Paranota not obvious. Slightly castellated, especially anteriorly. Relative width of pro- and metazonites 0.83–0.95. Prozonites with tubercles, but no setae, metazonites with abundant setae, none long, and tubercles. Prozonite with a channel-like area just in front of the border with the metazonite. Limbus very clearly crenulated under SEM. Ventral margin of pleurites almost straight, although with slightly bilobed margin in anterior few rings. Hind edge of pleurite from inside with clear but irregular tubercles, not serrate but with some setae. Ozopores very difficult to see. The original description does not report on which ring they start, but they were said to be on small protuberances; this may well be due to the state of preservation. In specimens viewed here, the protuberances were not obvious.

LEGS. Length relative to body height and length:width ratio of podomeres not analysed. Coxae tuberculate. Claw broadly expanded and paddle-shaped on anteriormost legs of males and females; by approximately leg pair 80 becoming more conventionally claw-shaped. Accessory claw: short, ¼–½ length of claw, quite broad and with rounded tip, arising from lateral side of claw.

TELSON. Length:width ratio 0.42–0.6.

ANTERIOR MALE LEGS (pairs 1–8). Appear normal.

ANTERIOR GONOPODS ( Fig. 2D ). Short and squat, with segments evidently fused together so exact number is difficult to see. Pair of gonopods appearing like two cupped hands with the cup facing ventrad. Ventral surface with setae but lateral surface without. No apparent enlarged setae or other structures at tip of anterior gonopods, including in slide-mounted syntype (note that in those illustrated in Fig. 2D tip of a posterior gonopod protrudes, looking like a structure at tip of anterior gonopods).

POSTERIOR GONOPODS. Not visible in situ in any specimens but original illustrations showed it to be of ‘typical’ siphonophorid type with last segment long, thin, with spine towards base and a simple doublepointed tip. Slide mount shows spine, although tip is not clear.

Remarks

All specimens were found at the same time of the year at the same location. The original description of R. hebetunguis describes ozopores situated on slight protuberances. However, in all the species described here (and in species of Columbianum as well, Read & Enghoff 2018) the ozopores are surrounded by a ring of setae. As noted earlier, this can sometimes give the appearance of the ozopores protruding. Examination of various species in the Natural History Museum in London revealed some with clear paranota, for example S. longirostris Silvestri, 1895 , unlike in any of those in the current collection. See Table 1 for a comparison of the features of S. hebetunguis and the other species of Siphonophora from Brazil, as well as S. portoricensis Brandt, 1837 .

The new species described below differ from S. hebetunguis in the structure of the anterior gonopods as well as in some other somatic characters. They do, however, have claws that are shaped similar to those described for hebetunguis .

Figures

Fig. 1. Relationship between body width (mm) against the total number of tergites with legs for new species of Siphonophora Brandt, 1837 and S. hebetunguis (Attems, 1951).

Fig. 2. Siphonophora hebetunguis (Attems, 1951), type specimen (NHMW 2295). A. Head and anterior rings, body width approximately 0.8 mm. B. Head in dorsal view. C. Head in lateral view. D. Male gonopods. E. Ventral margin of pleurite in lateral view, anterior to left. F. Claw. G. Mid-body limbus of male. H. Mid-body pleurite hind edge from inside (male). Scale bars: A = 800 µm; B–E = 200 µm; F–H = 10 µm.

Fig. 9. Claws and accessory claws in the three species of Siphonophora Brandt, 1837 studied here. A. Siphonophora hebetunguis (Attems, 1951). B. Siphonophora setaepromissa sp. nov. C. Siphonophora tuberculata sp. nov. Not to scale.

Tables

Table 1. Distinguishing features of species of Siphonophora Brandt, 1837 from Brazil.

	hebetunguis	pubescens	setaepromissa	tuberculata	portoricensis
Details taken from	type material	literature	fresh material	fresh material	literature
Overall size	up to 17 mm	up to 10 mm	up to 19 mm	up to 10 mm	holotype 17 mm
No. body rings	33–50	29–62	28–82	16–45	51–79
Head shape (dorsal view)	sinuous lateral margin	triangular	sinuous lateral margin	roughly triangular	more triangular
Mandible tip	unknown	unknown	sponge-like	pointed	unknown
Tubercles on head and collum	abundant	none mentioned	some	abundant	none mentioned
Caudal margin of collum	more or less straight	illustration ambiguous, perhaps slight anterior curve?	more or less straight	slightly curved caudally	shallow anterior curve
Tergite 2	> 0.5 length of collum	> 0.5 length of collum	approx. 0.5 length of collum	less than 0.5 length of collum	unknown
Claw shape	blunt & spoon-like	normal (probably)	blunt and spoon-like	broader than simple claw but not spoon-like	‘uncinate’ simple, perhaps broad
Accessory claw	short, to ½ length of claw	small	short, to less than ½ length of claw	short, to ½ length of claw	apparently absent
Limbus	crenulate	unknown	not crenulate	not crenulate	unknown
Coxae	tuberculate	smooth	smooth	tuberculate	unknown, appear smooth in illustration
Channel between pro- and metazonites	no setae visible in SEM	unknown	single line of setae and some tubercles	single line of setae, no tubercles	unknown
Tubercles on prozonites	present	unknown	absent	present	unknown
Pleurites ventral margin	slightly bilobed in anterior, rest more or less straight	sinuous	clearly bilobed	slightly bilobed in anterior, rest more or less straight	unknown
Relative length of pro-/ metazonites	0.83–0.95/1	unknown	0.82–0.95/1	0.66–0.92/1	unknown
Setal length	short	short	may be very long in some males	short	described as variable
Anterior gonopods	blunt-tipped; median lobe perhaps present; some setae near the tips	two subequal parts, large, each with rounded tips, one slightly hooked; no special structure near the tips; median lobe apparently missing	uneven ‘S’ shape; apex narrow, blunt and spoon-shaped; 1 large seta on mesal side on separate basis; several wide, ribbon-like setae near tip; median lobe present	large claw at tip 1 wide; ribbon-like seta on lateral side; median lobe may or may not be present	with a waist, apex rounded, lobe on medial side, no special structures at tip
Posterior gonopods	strongly tapering; spine near base; double-pointed tip	strongly tapering; no apparent spine near base; small claw-like tip	strongly tapering; large accessory spine near base; blunt tip	more parallel-sided; small spine near base; tip perhaps forked	strongly tapering, no obvious spine, slightly pointed tip