“Order Homalorhagida Zelinka, 1896
Family Pycnophyidae Zelinka, 1896
Genus Pycnophyes Zelinka, 1907
Pycnophyes neuhausi, n. sp. Higgins (Figs. 6–11)
Diagnosis. Pycnophyes with prominent posterior elongation of the tergal plate of segment 3, lateral margins of mid-sternal plate uneven; maximum sternal width at segment 3; lacking mid-dorsal spinose processes; mid-ventral thickenings on segments 10–12.
Description. Holotype, adult male, USNM 1025880 (Figs. 6–11) trunk length 600µm. Maximum sternal width, at segment 3, 166µm, 27.7% of trunk length. Standard width 134 µm. Lateral terminal spines 144 µm long, 24% of trunk length. Trunk shape begins tapering at segment 11. Second segment consisting of two distinct dorsal placids, one on either side of mid-line, and four slightly incised ventral placids.
Segment 3, 92 µm long, 166 µm wide. Posterior margin of tergal plate 3 extends posteriorly, ca. 25 µm beyond the beginning of the following segment (Figs. 7 and 8). Anterior margin of tergal plate sculptured, several muscle scars noted (Figs. 7 and 8 ms), prominent setae near dorsolateral margin. Mid-sternal plate of segment 3, 64 µm m long, 86 µm wide at posterior margin, 30 µm wide at anterior margin, bilateral thin areas near anterior margin, lateral margins wider (bulging) about mid-length of sternal plate. Episternal plates (Figs. 6 and 10 ep) with distinctive muscle scars, no setae noted.
Segment 4, 66 µm long, sternal width 152µm, prominent adhesive tubes, 44 µm long, centered on each sternal plate. Prominent sensory spots mesial to adhesive tubes, less prominent sensory spots lateral to each adhesive tube. Ventral pachycycli at tergosternal joints well developed, peg and socket joint prominent. Sensory setae at lateral margin of each sternal plate. Tergal plate with lateral setae and suggestions of sensory spots more mesial, muscle scars not prominent. No spinose projection of tergal plate at dorsal mid-line. Dorsoventral muscle scars about half the distance from mid-line to lateral margin, oriented as small diagonal marks.
Segment 5, 65 µm long, sternal width same as segment 4, 152 µm. Sensory setae on either side of ventral mid-line and posterior to mesial edge of ventral pachycycli. Sensory setae at lateral margins as in segment 4 and on tergal plate (si).
Segment 6, 64 µm long, sternal width 160 µm. Sensory setae at lateral margin of each sternal plate and paired setae about two-thirds from mid-line and near arthrocorium (line delineating attachment of one segment to another), possible sensory spot near mid-line, same position as sensory setae in segment 5. Tergal plate with small sensory spot centered on mid-line, otherwise similar to segment 5.
Segment 7, 68 µm long, sternal width 162 µm. Sensory setae at lateral margin, below tergosternal joint and near ventral mid-line. Tergal plate with sensory setae at lateral margin and at a more mesial position, otherwise similar to segment 6.
Segment 8, 68 µm long, sternal width 162 µm. Sensory seta centered on each sternal plate near arthrocorium. Mid-line margins of sternal plates becoming thickened. Tergal plate similar to that of segment 7. Segment 9, 72 µm long, sternal width 163 µm. Sensory seta as in previous segment, sensory spot lateral to setae and indication of second sensory spot mesial to setae. Tergal plate beginning to develop mid-ventral thickenings, elongate and slightly kidney-shaped, otherwise similar to that of segment 8.
Segment 10, 74 µm long, sternal width 160 µm. Sensory spots and setae similar to segment 9. Tergal plate with better-defined mid-ventral thickenings, otherwise similar to that of segment 9.
Segment 11, 74 µm long, sternal width 148 µm, trunk shape now begining to narrow. Mid-ventral thickenings (Figs. 6 and 11 mt) tergosternal joints (Figs. 6 and 11 tj) more prominent, setae and sensory spots similar to those of segment 10. Tergal plate with three possible sensory spots mid-way near arthrocorium, no lateral setae noted, otherwise similar to segment 10.
Segment 12, 74 µm long, sternal width 134 µm sensory spot centered between mid-line and lateral margin. Tergal plate with less prominent mid-ventral thickenings, sensory spots lateral to muscle scars and single sensory spot on dorsal mid-line anterior to muscle scars.
Segment 13, 30µm long, sternal width 84 µm, distinctive triangular area bounded by thickened pachycyclar material near mid-line of each sternal plate, replacing mid-ventral thickenings of this segment. Males with three penile spines (Figs. 6 and 11 ps) near anterior margin, each ca. 12 µm long. Lateral terminal spines robust, 144 µm long. Two minute knobs on either side of dorsal mid-line. Segment is completely overlapped by segment 12, which makes further observations unreliable.
Etymology. This species is named in honor of Prof. Dr. Birger Neuhaus, Berlin (Germany). He is a former post-doctoral student and now good friend and colleague of the junior author.
Type locality. Same as C. storchi n. sp.
Remarks. The genus Pycnophyes comprises 39 species. Of these, only two, P. odhneri Lang, 1949 and P. sculptus Lang, 1949 have been reported from the Atlantic Coast of South America and P. chiliensis Lang, 1953 is the only member of this genus reported from the Pacific Coast of South America. Five species of Pycnophyes have been reported from the Caribbean Sea (Higgins 1983), and two species from the Atlantic Coast of North America (Blake 1930; Higgins 1964).
P. neuhausi, n. sp. has several characters that are useful in making gross morphological comparisons. First, the shape of the trunk (segments 3–13) is nearly even throughout its first eight segments (segments 3–10). The trunk shape begins to narrow at segment 11. The average sternal width of segments 3–12 is 140 µm, ca. 23% of the trunk length (600µm) Most species of Pycnophyes have a narrower first trunk segment. Second, the mid-sternal plate bulges about 0.4 µm distance from the anterior margin. This character is found in several species that are otherwise similar. The first of these is P. egyptensis Higgins, 1966 which also has nearly the same trunk measurements and same lateral terminal spine length and proportions to the trunk as P. neuhausi n. sp. although these spines in P. neuhausi n. sp. are slightly thinner than those noted by Higgins (1966) for P. egyptensis. Two features distinguish the former from the latter: first, P. neuhausi n. sp. has a pronounced posterior extension of the tergal plate at the mid-line in segment 3 (Fig. 7) and the mid-ventral thickenings of the sternal plates are less developed but present on segments 10–12 as contrasted to P. egyptensis where these are well-developed and present only on segments 11 and 12. Furthermore, it is unlikely that these species are conspecific considering the geographic separation.
Species that are within reasonable geographic limits include all of the Caribbean species: P. corrugatus, P. ecphantor, P. emarginatus, P. iniorhaptus, P. longicornis described by Higgins (1983). P. iniorhaptus is the only one of these species having a mid-sternal plate that bulges along its lateral margins in the manner of P. neuhausi n. sp. but it is distinguished from the latter by its long, tapering tunk shape, straight posterior margin on tergal plate 3, and arrangement of setae and terminal tergal margin. Of Lang’s species (Lang 1949, 1953), P. odhneri has a mid-sternal plate that curves mesially and has mid-dorsal spinose projections on segments 3–11. P. sculptus reported from South Georgia Island, is nearly 1000 µm long and has a maximum width of 230–250 µm, similar in proportion to P. neuhausi n. sp. Its lateral terminal spines are ca. 160 µm long, about 17% of the trunk length and very thin thereby contrasting with those of the new species. The shape of the terminal region of P. sculptus differs from that of P. neuhausi n. sp. and its mid-sternal plate has nearly straight margins. Unfortunately, P. sculptus is inadequately described. P. chiliensis (Lang, 1953) described from Quellin, Chile, has a mid-sternal plate with lateral margins curving mesially and a series of mid-dorsal spinose projections on most of the tergal plates.”
(Martorelli & Higgins, 2004: 88-92)
